5.0 Implementation Program

The goals set forth in Section 4.0, Resource Management Goals and Strategies will require an integrated set of programs and projects oriented toward the conservation and improvement of water resources within the watershed and identifies parties responsible for each activity.   The following sections describe generally the activities that will be undertaken by various parties. Table 27 in Section 5.9 provides a cost estimate and schedule for the District’s responsibilities for new activities in the implementation program.

5.1 Regulatory Program

As discussed in Section 3.6 above, future development is not expected to contribute significant additional stormwater volume or phosphorus loads to Minnehaha Creek.  However, an overall reduction in phosphorus loading from the subwatershed is desirable and additional reductions from regulation of pollutant loading and volume should be considered.  Additional infiltration and minimization of new impervious surface should be encouraged to reduce pollutant loading from runoff, help restore base flow in the creek and reduce peak runoff rates.  To decrease pollutant loading, control new volumes, encourage increased infiltration and provide for additional wetland management, additional regulation may be necessary.  A decision on rulemaking needs/standards can only be made after the formal rulemaking process.  In addition, further amendments to the Rules should not be precluded by the content of the plan.

Additional regulatory controls on permitted development and redevelopment will be considered for this subwatershed to increase phosphorus load reduction requirements, add volume management and infiltration requirements, implement wetland management in accordance with management classification, and increase scrutiny of development that may impact groundwater or key conservation resources.  Regulations providing an incentive such as a volume reduction credit to developers to maintain undisturbed areas, reforest, or plant native vegetation may be considered.

The following are revised or additional regulatory controls in this subwatershed that would be necessary to assist the District in meeting the goals of this Plan:

  1. Amend existing or establish new District rules requiring abstraction of the first one inch of rainfall on new permitted development and redevelopment.
  2. Amend existing or establish new District rules requiring greater than 50 percent phosphorus removal on new permitted developments within the subwatershed
  3. Amend District rules to incorporate a requirement for stormwater management plan approval prior to submittal of a preliminary plat.
  4. Amend existing or establish new District rules requiring submittal of a functions and values assessment for all proposed wetland impacts requiring a permit; mitigation of all fill in Preserve category wetlands; and specifying by management classification stormwater discharge pretreatment, buffer, hydroperiod, and other wetland standards.
  5. Establish new District rule requiring an additional level of analysis and review of permitted development and redevelopment where there is a potential to adversely impact groundwater connected to a surface water feature.
  6. Require pretreatment of stormwater discharged to wetlands or infiltration areas in the areas of high aquifer sensitivity.

5.2 Land Conservation Program

The opportunity exists to create connections between ecosystems within the Lake Minnetonka subwatersheds and the Mississippi River to improve water quality, preserve natural conveyances, and facilitate the movement and proliferation of native species as well as enhance recreational opportunities.  The District will prioritize Land Conservation Program activities in the Minnehaha Creek Subwatershed based on meeting one of the following criteria:

  • § Connecting or expanding existing public lands;
  • § As part of a restoration project; or
  • § Leveraging redevelopment opportunities.

Figure 19 identifies priority areas in the watershed, the conservation of which will improve the characteristics of the aquatic ecosystem and the water quality within the subwatershed as well as areas downstream.  

The District operates a Land Conservation Program that undertakes conservation activities ranging from assisting property owners in enrolling property in conservation programs to acquiring easements or fee title over high value resources.   Some of the key conservation areas identified on Figure 19 are located within a current Land Conservation Program target area or have been proposed for addition to the target area.   The District will continue to proactively investigate opportunities to conserve key resources within the Minnehaha Creek subwatershed, and will work cooperatively with other agencies and groups to accomplish this subwatershed’s conservation goals.  The District will provide technical assistance to the LGUs to identify and implement strategies for local conservation efforts in support of program goals.

5.3 Education Program

The District operates a watershed-wide Strategic Education and Communications program that provides general information of wider interest as well as targeted information.  The targeted education and public involvement activities identified in this plan will be implemented to assist in the reduction of existing pollutant loading to Minnehaha Creek, the lakes, and other water resources in the subwatershed as well as increasing infiltration within the subwatershed.

5.4 Monitoring and Data Collection

Hydrologic Data Program

To monitor progress toward meeting water quality and quantity goals, routine monitoring of Minnehaha Creek will continue to be a part of the District’s annual Hydrologic Data program.   Macroinvertebrate monitoring will be completed on Minnehaha Creek every five years.  The District will continue to partner with the Minneapolis Park Board as it monitors water quality in the city lakes.

Aquatic Vegetation

Comprehensive aquatic vegetation data is available for many but not all the lakes within the subwatershed.  The District will work in partnership with the Minneapolis Park Board and other local governments to obtain aquatic vegetation data and to develop vegetation management plans for those lakes. 

Wetland Monitoring

Wetlands with exceptional value vegetation are present in the subwatershed.  Because of the importance to overall subwatershed ecological integrity of preserving these values, these wetlands will be regularly monitored for invasive species by staff or trained volunteers or in cooperation with the Minneapolis Park Board. 

5.5 Operations and Maintenance

Activities detailed in this implementation plan will require new operations and maintenance activities in this subwatershed.  These include:

Table 14.  Ongoing District operations and maintenance tasks in the Minnehaha Creek subwatershed.

Task

Spring

Summer

Fall

Inspect Erosion-Prone Reaches of Creek

Early Spring and After Storm

After Storm

Late Fall and After Storm

Inspect High Vegetative Diversity Wetlands

Regularly

Regularly

Regularly

Inspect channel dredging project area for sediment accumulation: West 44th Street to TH 100

 

Annually

 

Remove debris in Minnehaha Creek and other streams that poses an obstruction to flow or causes flooding

As needed

As needed

As needed

Inspect channel improvement project area for proper operation: 300 feet upstream of TH 100

 

Annually

 

Table 15.  Ongoing District operations and maintenance tasks for the Minnehaha Creek subwatershed canoe facilities.

Task

Responsible Parties

Spring

Summer

Fall

Routine Inspection

MCWD

After Snowmelt

June

September

Debris and Trash Removal

MCWD

As needed

As needed

As needed

Minor Erosion Repair

MCWD

As needed

As needed

As needed

Temporary and Permanent Sign Maintenance

MCWD

As needed

As needed 

As needed

Fence and Barrier Maintenance

MCWD

As needed

As needed 

As needed

Portage and Landing Maintenance

MCWD

As needed

As needed

As needed

Table 16.  Ongoing District operations and maintenance tasks for previously completed Minnehaha Creek subwatershed improvement projects.

Task

Water Quality Monitoring

Structural Repair

Major Erosion Repair

Sediment removal

Twin Lakes Park Pond

As Needed

As Needed

As Needed

As Needed

Cedar Meadows Pond

As Needed

As Needed

As Needed

As Needed

Lake Calhoun Ponds

As Needed

As Needed

As Needed

As Needed

Lake Nokomis Ponds

As Needed

As Needed

As Needed

As Needed

Pamela Park Ponds

 

 

 

As Needed

Table 17.  Potential ongoing operations and maintenance tasks for proposed Minnehaha Creek subwatershed improvement projects.

Task

Treat-ment Ponds

Wetland Restorations

Stream Restorations

Spring

Summer

Fall

Routine Inspection

a

a

a

Early and After Storm

After Storm

Late and After Storm

Vegetation Management

 

a

a

As needed

As needed

As needed

General Upkeep

a

a

 

Regularly

Regularly

Regularly

Debris and Trash Removal

a

 

 

As needed

As needed

As needed

Inlet/Outlet Cleaning

a

a

 

As needed

As needed

As needed

Minor Erosion Repair

a

a

a

As needed

As needed

As needed

Note: Responsible parties would be determined by negotiation at the time of project proposal

5.6 LGU Requirements

5.6.1 Local Government Unit Subwatershed Phosphorus Load Reductions

The HHPLS and the Lake Hiawatha TMDL have identified a need to reduce phosphorus loading to Minnehaha Creek to achieve a goal of an in-creek total phosphorus concentration of 80 ug/L.  An approximate 8 percent load reduction was identified to be achieved through small-scale infiltration BMPs.   The distribution of that load reduction is shown in Table 18 below.  An additional 8 percent load reduction is identified to be achieved through near- and in-creek improvements.   At this time, insufficient information is available regarding in-stream processes that might also be contributing to phosphorus concentrations, including streambank erosion, internal loading in the impoundment areas, and contributions from riparian wetlands.  This plan recommends completion of a Minnehaha Creek Diagnostic Study to identify those internal sources and potential reductions from internal and streambank improvements prior to allocating that additional 8 percent load reduction to potentially collaborative construction projects as well as an additional allocation of phosphorus load reduction to upstream cities.

This plan promotes the general application of BMPs such as increased street sweeping, local water quality ponds, rain gardens and infiltration swales.  The LGUs must annually report to the District their progress toward accomplishing this requirement.

Table 18.  Allocation of Minnehaha Creek subwatershed general small-scale infiltration practices load from lakes TMDL as LGU Phosphorus Load Reductions (lbs/yr).

LGU

Lake Hiawatha 

Lake Nokomis 

Diamond Lake 

Wayzata

3

 

 

Minnetonka

121

 

 

Plymouth

10

 

 

Hopkins

34

 

 

St. Louis Park

172

 

 

Edina

67

 

 

Golden Valley

2

 

 

Minneapolis

217*

24

62

Richfield

0

36

 

Ft. Snelling

0

6

 

TOTAL

626

66

62

*Includes 28 pound reduction in Lake Harriet lakeshed (see Table 19) and 22 pound reduction in Diamond  Lake lakeshed, see Table 22.  

5.6.2 Land Conservation

A key element in achieving overall ecological integrity goals in the Minnehaha Creek subwatershed is the conservation of key ecological areas, including high-value wetlands and connecting uplands, within the Minnehaha Creek corridor.  LGUs must identify in their local water management plans the areas shown on Figure 19.  The local plan must also identify strategies the LGU will undertake to protect the ecological values of those areas.  These may include such strategies as land use regulation; acquisition and management; conservation easements; ecological restoration; and property owner education regarding land management strategies to maintain ecological integrity.

5.6.3 Other Issues

Landlocked Basins

There are existing land-locked subwatershed units and basins within this subwatershed that the cities have been considering for outlet drainage projects.  To protect the quality of downstream resources, local plans must either no longer consider this an option, or demonstrate how this could be achieved without impact to downstream water quantity or quality impacts. Outletting will generally be discouraged unless there is a demonstrated threat to property structures or public safety.

5.7 Phosphorus Load Reduction

One of the water quality goals for this subwatershed is the reduction of phosphorus loading into the Creek and lakes that exceed their total phosphorus goal or that are subject to a TMDL load reduction requirement.

Tables 19, 20, 21, 22 and 23 break down modeled phosphorus loading to each lake by source: atmospheric deposition, external sources, and internal sources.  Atmospheric deposition is a regional issue and is not dealt with here.  The primary means of addressing external loading are through the regulation of new loads generated by development and the reduction of existing loads from the subwatershed.

In some cases the phosphorus load contributed from the subwatershed is not sufficient to explain the current in-lake phosphorus concentration.  The most likely sources for this discrepancy are internal loading from lake sediments or aquatic vegetation.  Internal load management such as alum treatment to control sediment sources coupled with control of aquatic vegetation often helps to alleviate some internal loading.  Rough fish management may also be required.  A feasibility study would determine the most appropriate internal load reduction options.   

Minnehaha Creek

The HHPLS identified a need to reduce phosphorus loading to Minnehaha Creek to achieve a goal of an in-creek total phosphorus concentration of 80 ug/L.  See Section 5.6.1 for a discussion of load reduction strategies.

Brownie Lake

Brownie Lake is at or very near its phosphorus, chlorophyll, Secchi transparency, and TSI goals, and is not expected to change significantly due to development.  The emphasis in the future will be on the prevention of degradation of water quality.

Cedar Lake

Cedar Lake is better than its phosphorus, chlorophyll, Secchi transparency, and TSI goals, and is not expected to change significantly due to development.  The emphasis in the future will be on the prevention of degradation of water quality.

Lake of the Isles

Lake of the Isles meets or is better than its phosphorus, chlorophyll, Secchi transparency, and TSI goals, and is not expected to change significantly due to development.  The emphasis in the future will be on the prevention of degradation of water quality.

Lake Calhoun

Lake Calhoun is better than its phosphorus, chlorophyll, Secchi transparency, and TSI goals, and is not expected to change significantly due to development.  The emphasis in the future will be on the prevention of degradation of water quality.

Lake Harriet

Lake Harriet water quality has been improving.  Although the long-term average of 23 μg/L is still slightly higher than its total phosphorus goal of 20 μg/L, water quality is very good.  Table 19 sets forth a summary plan for how load reductions could be accomplished.

Table 19.  Phosphorus load reduction plan for Lake Harriet (Goal = 20 μg/L).

Source

Reduction 

Ultimate Phosphorus Load [lb/yr]  

Planned Reductions [lb/yr]  

Final Loading [lb/yr]  

  

Atmospheric

Atmospheric deposition

NA

85

NA

85

 

External Loads

External load determined from modeling land use

 

543

 

 

  

 

 Existing Regulations

 

21

 

 

 

LGU load allocation (Table 18)

 

28

 

 

 Total After Reductions

 

 

 

494

 

Internal / "Unknown" Loads

 Internal/“unknown"

loads determined

from  modeling land use

 

37

 

 

  

 

 Internal load management

 

26

 

 

 Total After Reductions

 

 

 

11

 

Total Load

 TOTAL 

 

665

 

590

  

 LOAD GOAL  

 

 

 

562

 

 DIFFERENCE 

 

 

 

28

 Adaptive

 management

Lake Nokomis

A TMDL study including a phosphorus reduction plan is currently being developed for Lake Nokomis.  Proposed reductions include: reductions due to the new prohibition on the use of fertilizer with phosphorus; proper operation of the Lake Nokomis weir; application of neighborhood-level BMPs to increase infiltration and treat stormwater; and internal load management.  A diagnostic and feasibility study would be required to evaluate internal load management in more detail.  Table 20 sets forth a summary plan for how load reductions could be accomplished, in accordance with the TMDL.

Table 20.  Phosphorus load reduction plan for Lake Nokomis (Goal = 50 μg/L).

Source 

Reduction 

Ultimate Phosphorus Load [lb/yr]

 

Planned Reductions [lb/yr]  

Final Loading [lb/yr]  

  

Atmospheric

Atmospheric deposition

NA

49

NA

49

 

External Loads

External load determined from modeling land use

 

453

 

 

  

   Reductions

Phosphorus free fertilizer

 

31

 

 

   proposed in the

Operate weir

 

104

 

 

   draft TMDL

General BMP load reductions: sweeping,

neighborhood BMPs,

infiltration

 

66

 

 

 

 

 

 

 

 

 

 

 

 

   Regulation

Existing regulations

 

13

 

 

Total After Reductions

 

 

 

239

 

Internal / "Unknown" Loads

Internal/“unknown"

loads determined

from  modeling land use

 

406

 

 

  

 

 Internal load management

 

90

 

 

 Total After Reductions

 

 

 

316

 

Total Load

 TOTAL 

 

908

 

604

  

 LOAD GOAL  

 

 

 

599

 

 DIFFERENCE 

 

 

 

5

 

Lake Hiawatha

A TMDL study including a phosphorus reduction plan is currently being developed for Lake Hiawatha.  Lake Hiawatha receives direct inflow from Minnehaha Creek, and is greatly influenced by the creek’s water quality and the amount of flow, making developing specific load reductions difficult.   Proposed reductions from the TMDL include: reductions due to the new prohibition on the use of fertilizer with phosphorus; construction of the proposed Hiawatha Golf Course ponds and other BMPs; application of neighborhood-level BMPs to increase infiltration and treat stormwater; reduction of phosphorus loading in Minnehaha Creek through streambank stabilization and buffer restoration; and other BMPs throughout the watershed such as increased street sweeping, retrofits of infrastructure, etc.  Table 21 sets forth a summary plan for how the reductions could be accomplished, in accordance with the TMDL.

Table 21.  Phosphorus load reduction plan for Lake Hiawatha (Interim Goal = 61 μg/L).

Source 

Reduction 

Ultimate Phosphorus Load [lb/yr]

 

Planned Reductions [lb/yr]  

Final Loading [lb/yr]  

  

Atmospheric

 Atmospheric deposition

NA

15

NA

15

 

External Loads

External load determined

from modeling land use

 

10,917

 

 

  

   Reductions

Phosphorus free fertilizer

 

355

 

 

   proposed in the

Golf course, other ponds

 

46

 

Local projects

   draft TMDL

Increase infiltration

 

626

 

 

 

Creek improvements

 

626

 

 

 

Other specific BMPs

 

53

 

Local prpojects

   Regulation

Existing Regulations

 

302

 

 

Total After Reductions

 

 

 

8,909

 

Internal / "Unknown" Loads

Internal/“unknown"

loads determined

from  modeling land use

 

194

 

 

  

 

 Internal load management

 

----

 

 

 Total After Reductions

 

 

 

194

 

Total Load

 TOTAL 

 

11,126

 

9,118

  

 LOAD GOAL  

 

 

 

10,038

 

 DIFFERENCE 

 

 

 

(-920)

 

Diamond Lake

A TMDL study including a phosphorus reduction plan is currently being developed for Diamond Lake.  Proposed reductions from the TMDL to reach the lake’s interim goal of 90 ug/L include: reductions due to the new prohibition on the use of fertilizer with phosphorus; increased street sweeping; application of neighborhood-level BMPs to increase infiltration and treat stormwater; treatment of runoff from an industrial area in subwatershed MC-142; and lake biomanipulation to reduce internal loading.  A diagnostic and feasibility study would be required to evaluate internal load management in more detail.  Table 22 sets forth a summary plan for how load reductions could be accomplished in accordance with the TMDL.

Table 22.  Phosphorus load reduction plan for Diamond Lake (Interim Goal = 90 μg/L).

Source 

Reduction 

Ultimate Phosphorus Load [lb/yr]

 

Planned Reductions [lb/yr]  

Final Loading [lb/yr]  

  

Atmospheric

Atmospheric deposition

NA

15

NA

15

 

External Loads

External load determined from modeling land use

 

260

 

 

  

Reductions

proposed in the

draft TMDL

Phosphorus free fertilizer

 

26

 

 

General BMP load reductions: sweeping,

neighborhood BMPs,

infiltration

 

84

 

Local projects

MC-142 runoff improvement

 

18

 

Local project

   Regulation

Existing regulations

 

15

 

 

Total After Reductions

 

 

 

121

 

Internal / "Unknown" Loads

Internal/“unknown"

loads determined

from  modeling land use

 

211

 

 

  

 

 Internal load management

 

95

 

 

 Total After Reductions

 

 

 

116

 

Total Load

 TOTAL 

 

486

 

252

  

 LOAD GOAL  

 

 

 

265

 

 DIFFERENCE 

 

 

 

(-13)

 

Powderhorn Lake

A TMDL study including a phosphorus reduction plan is currently being developed for Powderhorn Lake.  Proposed reductions from the TMDL to reach the lake’s interim goal of 90 ug/L include: reductions due to the new prohibition on the use of fertilizer with phosphorus; addition of a filtration system on the CDSs on the outfalls; increased street sweeping; application of neighborhood-level BMPs to increase infiltration and treat stormwater; and lake biomanipulation to reduce internal loading.  A diagnostic and feasibility study would be required to evaluate internal load management in more detail.  Table 23 sets forth a summary plan for how load reductions could be accomplished in accordance with the TMDL.

Table 23.  Phosphorus load reduction plan for Powderhorn Lake(Interim Goal = 90 μg/L).

Source 

Reduction

Ultimate Phosphorus Load [lb/yr]

 

Planned Reductions [lb/yr]  

Final Loading [lb/yr]  

  

Atmospheric

 Atmospheric Deposition

NA

2

NA

2

 

External Loads

 External Load Determined

 from Modeling Land Use

 

126

 

 

  

   Reductions

Phosphorus free fertilizer

 

15

 

 

   proposed in the

Increased street sweeping

 

24

 

 

   draft TMDL

Increase infiltration

 

2

 

 

 

Filtration on CDSs

 

31

 

 

   Regulation

Existing Regulations

 

-

 

 

Total After Reductions

 

 

 

54

 

Internal / "Unknown" Loads

Internal/“Unknown"

Loads Determined

from  Modeling Land Use

 

139

 

 

  

 

 Internal load management

 

104

 

 

 Total After Reductions

 

 

 

35

 

Total Load

 TOTAL 

 

267

 

91

  

 LOAD GOAL  

 

 

 

90

 

 DIFFERENCE 

 

 

 

(-1)

 

5.8 Capital Improvement Program

Capital projects in the Minnehaha Creek subwatershed include stream restoration projects to repair erosion and improve habitat as noted in the Minnehaha Creek Steam Assessment; and projects to maintain existing infrastructure and improvements.

These projects and others identified below will progress the District toward achieving its various goals for the subwatershed. This program is not a comprehensive list of all capital needs or potential projects within the subwatershed, and is limited by available financial resources and staff capacity to manage projects. These priority projects are intended to:

  • Progress improvements to water quality as identified in the TMDLs for the lake in the subwatershed.• Stabilize, restore and improve biotic integrity reaches of Minnehaha Creek as identified in the Minnehaha Creek Stream Assessment.
  • Mitigate the impacts of development on downstream resources.

These proposed projects emphasize the achievement of multiple objectives. For example, stream restoration would not only stabilize streambanks and prevent further erosion, it would provide an opportunity to improve in-stream and buffer habitat, conserve existing high-value resources, and reduce sediment and nutrient transport downstream.

5.8.1 Minnehaha Creek Diagnostic Study/TMDL

ProjectMinnehaha Creek Diagnostic Study and Biotic Integrity TMDL
DescriptionA study to identify in-stream processes that might be contributing to phosphorus concentrations in the creek and in Lake Hiawatha as well as stressors that might be contributing to impaired biological integrity in Minnehaha Creek.
Need

This study is part of the effort to prepare and/or implement two Total Maximum Daily Load (TMDL) studies for water resources in the Minnehaha Creek subwatershed. Lake Hiawatha, which is in-line to Minnehaha Creek, has been designated by the MPCA and EPA as an Impaired Water for excess nutrient concentrations that lead to excessive algae blooms and poor water clarity. Phosphorus transported by Minnehaha Creek is the primary source of those excess nutrients. To help achieve Lake Hiawatha water quality goals, the Hiawatha TMDL study estimated that the total phosphorus load from nonpoint sources in the watershed must be reduced by at least eight percent and the load contributed from near- and in-stream processes to be reduced by an additional eight percent. This Diagnostic Study would identify in-stream processes that might be contributing to phosphorus concentrations in the creek and in Lake Hiawatha, including streambank erosion, internal loading in the impoundment areas, and contributions from riparian wetlands. This study would also identify potential reductions from internal and streambank improvements as a means of determining what part of the eight percent load reduction allocated to near- and in-stream improvements can actually be achieved, and whether additional watershed load reductions would be necessary to meet overall phosphorus reduction goals.

Minnehaha Creek itself has been designated an Impaired Water because of its impaired biologic community. Many of the processes that the Diagnostic Study will evaluate are also likely stressors to the biotic community. Combining the Diagnostic Study and Biotic Integrity TMDL would be efficient and would provide for the coordination of implementation efforts. For example, streambank erosion is often a contributor of sediment and phosphorus loading downstream. Biostabilization with native vegetation reduces that pollutant source while improving fish and macroinvertebrate habitat.

OutcomeAn implementation plan identifying the most effective suite of projects to reduce phosphorus and sediment loading and to restore ecological integrity
Estimated Cost and FundingDiagnostic and TMDL study. The District has received a grant from the MPCA to complete this study in 2006-2007.$150,000
Schedule2006

5.8.2 Minnehaha Creek Stream Restoration

The 2003 Minnehaha Creek Stream Assessment identified numerous areas of erosion along the length of the creek, as well as a general lack of steam complexity and lack of habitat for macroinvertebrates and fish largely driven by stream aggradation in impounded areas often upstream of artificial grade controls.  Based on these stressors and its flow regime Minnehaha Creek has been designated by the State as an Impaired Water for fish communities.  Minnehaha Creek is also listed as impaired for chlorides, dissolved oxygen, and bacteria (E. Coli).  The Minnehaha Creek Visioning Partnership identified erosion control, the improvement of conditions for aquatic life, and the improvement of aesthetic appearance as high priorities for future creek corridor management.  In 2012 the District completed a second Stream Assessment to evaluate the geomorphology and ecological health changes over time.  The 2012 Stream Assessment identified a general need for additional projects beyond those identified in the 2007 capital improvement program.  General recommendations for improving the ecological integrity, natural aesthetic and recreational value of Minnehaha Creek include but are not limited to: removing or modifying grade controls to allow fish passage and a more natural hydrologic condition; preserving and expanding wooded/vegetated riparian buffers along the entire stream length; reconstructing or remeandering channel and floodplain where space allows to improve geomorphic/hydrologic form and function and in-stream habitat; stabilizing banks using bioengineering techniques; establishing areas to preserve and enhance view-sheds; and establishing recreational corridor connectivity through passive uses such as trails and vistas.

Over the planning period the District will partner with riparian cities, property owners, other agencies, and infrastructure owners to accomplish stream restoration projects that will meet multiple objectives for water quality, biotic improvement, education and recreation.  Stream restoration projects would enhance riparian corridor vegetation; stabilize streambanks through bioengineering; add fish and macroinvertebrate habitat; create pool-riffle complexes; incorporate woody debris; remove select grade controls; and enhance educational and recreational opportunities through the creation of vistas and trail corridors designed to complement and protect the stable and restored streambank environment.

The CIP includes proposed improvements to several high-priority reaches as identified in the 2003 Minnehaha Creek Stream Assessment.   Priority reaches are those where stream restoration could improve streambank stability to “Good” as measured by Pfankuch stability rating relative to Rosgen stream type, or those where the Stream Visual Assessment Protocol (SVAP) mean score could be improved to 5.0 or better, or by one full point.  Specific improvements are guided and refined by the results of the Minnehaha Creek Diagnostic Study, the Minnehaha Creek Biotic Integrity TMDL, the 2003 Minnehaha Creek Stream Assessment, the findings of the Minnehaha Creek Visioning Partnership, the 2012 Minnehaha Creek Stream Assessment, opportunities for partnership, future studies, and individual reach needs and opportunities.   Figure 20 illustrates the location of priority reaches based on the 2003 Stream Assessment.  Not all of these reaches were prioritized in the 2007-2017 CIP.  Those that were not included are Reach 2, Reach 11, Reach 18, and Reach 29. 

The list of specific reaches below reflects priorities determined based on available data to date.  However, over the term of this plan, the District: (a) may shift funds between projects included under 5.8.2 to reflect immediate priorities and work scheduling decisions; and (b) may identify and implement projects within other reaches or incorporate project elements consistent with the goals of 5.8.2, on determining that those goals will be met and pursuant to the procedures described below.  There are two reasons for the District to reserve this ability to adjust project implementation on the basis of its ongoing review: 

(a) The District’s technical understanding of subwatershed hydrology and the hydraulic behavior of Minnehaha Creek will continue to develop and thereby refine the District’s capacity to determine where and what sorts of improvements will be most cost-effective.  The ongoing work described on the preceding page and similar ongoing diagnostic work likely will identify additional sites that merit attention during the planning period.

(b) The Minnehaha Creek corridor is fully developed and land prices are high.  The riparian edge is intensively used by private homeowners and commercial/industrial uses in the upper corridor and by the public on Minneapolis Park and Recreation Board (MPRB) lands within the lower corridor.  Stream restoration methods may impede intensive use and involve concepts and aesthetics for which there is not yet universal acceptance.  Securing landowner participation or easements for stream work is an uncertain prospect, or project opportunities may arise in an unanticipated way and subject to the property owner’s timeline.  Other opportunities may occur in the context of public road or utility work similarly driven by third-party time constraints.  The District accordingly must be prepared to respond to these opportunities.

Accordingly, the District intends to plan for and pursue implementation within the specific reaches enumerated below while also retaining the flexibility to pursue other opportunities as they arise.  With respect to the latter, there will be several project development elements to ensure transparency and public accountability:

(a) The District will continue to coordinate with the Cities of Minneapolis, Edina, St. Louis Park, Hopkins and Minnetonka and the MPRB to develop a more detailed understanding of hydrologic conditions in the subwatershed and Creek hydraulics and to confirm priority sites that meet District and municipal priorities. A focused feasibility study will be prepared for significant implementation actions to examine feasibility and cost-effectiveness.  The study will be made publicly available and presented to the Board of Managers at a public meeting with the availability for public comment.

(b) As described earlier in this plan, each year, for budget and levy purposes, the District will review the status of its capital program in a public forum with opportunity for public input.  Proposed revisions to the District’s 10-year CIP will be provided to Hennepin and Carver Counties and all cities wholly or partly within the District.  At its budget and levy hearing, the District Board of Managers will make budgeting decisions that will set overall parameters for spending under this capital project 5.8.2 and set specific project implementation priorities for the upcoming fiscal year.

(c) Before expending levied funds on designing or implementing a restoration activity, the Board will distribute design plans and provide public notice for a public hearing and project ordering in accordance with Minnesota Statutes §103B.251.  If the proposed work will exceed $300,000, the District will afford the additional procedures set forth in section 6.8 of the watershed plan (page 84).

Project Reach 4 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

 

 

This reach extends from 34th Avenue South to the Lake Hiawatha outlet weir.  It contains a number of storm sewer outfalls that require repair or improvement.  The riparian corridor is mostly turf grass maintained to an eroding creek edge.  The reach scored a 4.1 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone resulting in streambank undercutting and instability.  The reach includes spawning habitat, but lacks complexity of habitat features necessary to maintain a fish community.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features. 

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$944,100

Schedule

2013  Design, cooperative agreement

2014  Construction

Project Reach 6 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from the Hiawatha Golf Course bridge to the Lake Nokomis outlet, and flows through the Hiawatha Golf Course.  The riparian corridor is turf grass maintained to an eroding creek edge, with some riprap and a planted bank in one location.  The reach scored an extremely poor 2.9 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, due to a poor condition riparian zone and lack of fish and invertebrate habitat.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings that would not adversely impact play on the golf course.

Outcome

Stabilized streambanks with bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0 or at least one full point better than existing.

Estimated

Cost

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$451,000

Schedule

2014   Design, cooperative agreement

2015   Construction

Project Reach 7 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Lake Nokomis to Bloomington Avenue South.  It is channelized and stabilized with hard armoring.  A portion of this reach has been reconstructed with restored meanders and bioengineered banks.   The reach contains some erosion sites that require repair or improvement, including an exposed gas pipeline and a large box culvert whose discharge is creating erosion on the opposite bank.  The riparian habitat is poor, with some tree and shrub canopy and a narrow buffer of unmowed grass.  The reach scored a 4.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone and the altered channel.  The reach includes some fish habitat, but weirs and riprapped channels likely serve as passage barriers.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features.  The project would also evaluate the replacement of existing grade controls with a meandered, stepped pool design to improve habitat and eliminate barriers to fish movement. 

 

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0, or an improvement of one full point.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

 

$654,800

Schedule

2011   Design, cooperative agreement

2012  Construction

 

Project Reach 8 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Bloomington Avenue to Portland Avenue S.  It is an unstable channel with active cutting and deposition.  It contains a number of erosion sites that require repair or improvement, including an exposed gas pipeline.  The riparian corridor is mostly turf grass maintained to an eroding creek edge, although there are areas of the reach with good riparian woody vegetation.  Some streambank has been stabilized with hard armoring.  The reach scored a 5.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone resulting in streambank undercutting and instability.  The reach has few fish habitat features.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features. 

Outcome

Stabilized streambanks with bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$967,600

Schedule

2007  Design, cooperative agreement

2007  Construction

 

Project Reach 9 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Portland Avenue to Nicollet Avenue S.   The riparian corridor is mostly turf grass maintained to an eroding creek edge in some portions of the reach and a healthy riparian forest in others.  The reach includes fish spawning habitat.  The reach scored a 5.6 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to the areas of poor condition riparian zone resulting in streambank undercutting and instability.  There are several locations where falling brick walls, riprap, culvert inlets, and improperly placed riprap are causing streambank erosion issues.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings. 

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improvement in SVAP index to a score greater than 6.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$877,700

Schedule

2014    Design, cooperative agreement

2015   Construction

Project Reach 12 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Logan Avenue S to 54th Street.  It contains a number of storm sewer outfalls that require repair or improvement.  The riparian corridor is mainly turf grass maintained to an eroding creek edge and with some areas of stable banks with riparian tree and shrub growth.  The reach scored a 3.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to the poor riparian conditions and resulting unstable banks.   The reach includes areas with moderate in-stream fish habitat.  During the stream assessment, fish spawning was observed throughout the reach.  The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings.

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0, or an increase of one full point.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$1,380,100

Schedule

2015   Design, cooperative agreement

2016   Construction

Project

Reach 14 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from France Avenue S to 54th Street West.  Much of the riparian corridor is turf grass maintained to an eroding or riprapped creek edge, but the upper 900 feet is wooded.  The reach scored a 5.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to areas with poor-quality riparian vegetation.   The project would evaluate construction of in-steam habitat features and options for improving the riparian zone with native vegetation buffers.

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$896,000

Schedule

2011   Design, cooperative agreement

2012   Construction

Project

Reach 19-21 Restoration

Description

Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

Need

This reach extends from Meadowbrook Lake to Lake Street NE.  The reach has been channelized and straightened.  Where the Creek flows through Meadowbrook Golf Course, turf grass is maintained to steam edge.  The riparian corridor is a mix of turf grass and stable banks with riparian tree and shrub growth.  The reach scored a 7.0 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to fish barriers and lack of fish habitat, although spawning was observed during the assessment.  The project would evaluate the replacement of existing grade controls with a meandered, stepped pool design to improve habitat and eliminate barriers to fish movement.  Improvement of the riparian zone could include reforestation and establishment of native vegetation buffers.

Outcome

Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 7.0.

Estimated

Cost and Funding

Design, construction, project management, vegetation management contract.  Funding source for this project is the District capital levy.

$1,203,400

Schedule

2009   Design, cooperative agreement

2010   Construction

 

 

Overall Implementation Estimate (planning period):                                               $7,374,700

5.8.3 Minnehaha Falls/ Glen Restoration

ProjectMinnehaha Falls/Glen Restoration
DescriptionStreambank restoration, repair or replacement of retaining walls, bufferreestablishment, enhancement of in-stream habitat features
NeedA number of the retaining walls constructed by the Works ProgressAdministration and the Civilian Conservation Corps have deteriorated and are in need of restoration or replacement. Other needs for improvement in the area include trail and bridge abutments and correction of an ongoingdrainage issue that is causing deterioration of the public safety access road to the Creek mouth. The District will work collaboratively with theMinneapolis Park and Recreation Board and the National Park Service to identify and construct improvements. The specific share of construction cost as well as ongoing maintenance costs associated with these improvements would be determined by cooperative agreement prior to implementation of this project.
OutcomeProtection of public health and safety; stabilized streambanks with bothhard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat.
Estimated Cost and Funding

Phase I: Feasibility study

Phase II: Construct cooperative improvements.

Funding source for this project is the Districtcapital levy. The
specific share of construction costas well as ongoing maintenance
costs associatedwith these improvements would be determined
by cooperative agreement prior to implementation of this project.

$104,000 Ph I

$3,183,232 Ph II

$3,287,232 Total

Schedule

2007 Design, cooperative agreement

2008 Construction

5.8.4 Lake Nokomis Internal Load Management

ProjectLake Nokomis Internal Load Management
DescriptionDesign and implementation of strategies to reduce internal phosphorusloading, including: feasibility study; aquatic vegetation survey update andmanagement plan; fishery survey update and management plan; biomanipulation strategies that may include aquatic vegetationmanagement, zooplankton community and fishery manipulation, andchemical treatment.
Need

A TMDL study including a phosphorus reduction plan is currently being developed for Lake Nokomis. Proposed reductions include control of external sources of phosphorus through various efforts in the watershed and internal load management.

Strategies may include aquatic vegetation management, biomanipulation and fishery management, or chemical treatment. The specific share of construction cost as well as ongoing costs associated with this project would be determined by cooperative agreement prior to implementation of this project.

Outcome

Reduction in phosphorus load from internal sources estimated at 90 pounds annually; improved water clarity; more diverse aquatic vegetation community; improved aesthetics.
Estimated Cost
Investigation, permitting, implementation, and project
management. The District’s final cost share and any
ongoing maintenance responsibilities would be
determined by the negotiation of a cooperative
agreement with the city of Minneapolis andMinneapolis
Park and Recreation Board.

$30,600 Feasibility

$311,500 Implement

$342,100 Total

Schedule

2007 Fish, vegetation, and zooplankton surveys, development of management plans, cooperative agreement

2007 Implementation of strategies

5.8.5 Regional Volume and Load Reducation

Project

Minnehaha Creek Regional Volume and Load Reduction

Description

Implementation of opportunities to reduce stormwater volumes and nutrient loading, including but not limited to construction of infiltration basins and devices, wetland restoration, reforestation, revegetation, and stormwater detention or redirection.

Need

The Minnehaha Creek-Lake Hiawatha TMDL draft report (March 25, 2013) identifies the need to reduce phosphorus and bacterial (E. coli) loading to meet water quality targets for Lake Hiawatha and Minnehaha Creek. The TMDL draft report calls for a reduction of 1,907 lbs/year throughout the subwatershed in order for Lake Hiawatha to meet an in-lake nutrient concentration of 50 ug/L.  The TMDL draft report also identifies a need to reduce bacterial (E. coli) loading in order to meet the standard of 126 organisms/100 ml.  At this time with our current understanding, the best approaches for addressing excess bacteria loads appear to be source reduction or volume control practices.

 

In addition, the 2003 Minnehaha Creek Stream Assessment identified two major issues impacting water quality and biotic integrity in the Creek: flashy storm event flows that often result in streambank erosion; and low base flows, which reduce habitat and limit biotic integrity.  The high percent of impervious surface in this urbanized subwatershed has reduced the amount of stormwater that naturally infiltrates to surficial groundwater and which helps sustain base flow.  This stormwater is efficiently conveyed to the creek through stormsewers, which results in the flashy flows.

 

The Stream Assessment analyzed options for reducing peak discharges in Minnehaha Creek, and identified 11 key subwatersheds where reduction of peak discharge from the subwatersheds would collectively result in the greatest reduction in peak discharge in the Creek.  In these 11 subwatersheds, hypothetical ponds reducing peak discharge by 75 percent would result in a 27 percent reduction in Creek discharge at Cedar Avenue.  Regional infiltration or other abstraction or detention focused on those subwatershed units would have the most impact on reducing peak flows in Minnehaha Creek.

 

Specific project locations and methods will be identified and implemented to reduce nutrient and bacterial loading to Minnehaha Creek and thus to Lake Hiawatha; decrease peak discharge rates in Minnehaha Creek to reduce streambank erosion; and increase baseflow in the Creek to improve its biotic integrity.  These projects are intended to reduce annual volume and peak flows discharged to the Creek; increase infiltration to surficial groundwater; and reduce nutrient and bacterial export to the Creek.

 

Identifying specific implementation sites under this capital project element will be an ongoing process informed by refined technical knowledge of pollutant sources and geomorphological phenomena, available land and willing public or private partners.  Priorities are set foremost by diagnosing the spatial distribution of pollutant loading to Minnehaha Creek.

 

For example, on the basis of available data, subwatershed units between West 34th Street and Excelsior Boulevard are the source of greatest phosphorus loading to Minnehaha Creek, both in absolute amount and on a unit area basis.  Unit area loads for each subwatershed unit are determined by dividing the total phosphorus increase for each subwatershed unit by the area.

 

The list of specific implementation sites below reflects priorities determined based on available data to date.  However, over the term of this plan, the District: (a) may shift funds between projects included under 5.8.5 to reflect immediate priorities and implementation decisions; and (b) may identify and implement projects at other locations as well, on determining that the goals of 5.8.5 will be met and pursuant to the procedures described below.  There are three reasons for the District to reserve this role for its ongoing review:

 

(1) The District’s technical understanding of subwatershed hydrology and the hydraulic behavior of Minnehaha Creek will continue to develop and thereby refine the District’s capacity to determine where and what sorts of improvements will be most cost-effective. For instance, in 2011 the MCWD and the Mississippi Water Management Organization awarded a Joint Watershed Research Grant to the University of Minnesota to study stream base flow in Minnehaha Creek. The focus of the research is on investigating whether stormwater runoff can be infiltrated and stored in the shallow aquifer to contribute to stream base flow in Minnehaha Creek during periods of low flow and drought conditions. This study is ongoing and could help inform preferred locations for infiltration.

 

(2) Metropolitan area municipalities and the Minneapolis Park and Recreation Board (MPRB) are key District partners.  Municipalities are implementing their own comprehensive land use plans.  They are subject to legal obligations to reduce annual stormwater volumes and pollutant loadings, and to manage stormwater in ways that may be compatible with District objectives or which may be in conflict with them.

 

For example, the City of Minneapolis is obligated by the Metropolitan Council Environmental Services to reduce stormwater that enters the sanitary sewer system.   Actions such as disconnecting rooftop rain leaders from the sanitary system and completing the separation of combined sewers may increase the volume of annual stormwater runoff in the subwatershed, or may create or exacerbate local flooding issues.  Other LGUs in the subwatershed are required, under the Nondegradation requirement of their NPDES Phase II permits, to reduce annual stormwater volumes to at least 1988 volumes.

 

The District endeavors to work very closely with these public partners and is committed to investing funds where they will best serve the combined needs of involved public entities.  For this reason, the District needs to be prepared to be responsive to municipal needs and partnership interests as they evolve and arise.

 

(3) The Minnehaha Creek subwatershed is fully developed, land use is intensive and land prices are high.  For these reasons, the District must be opportunistic with respect to siting opportunities.  Opportunities may arise in conjunction with private redevelopment, public road reconstruction, MPRB capital work and other situations in which the opportunity occurs unexpectedly and is subject to the partner’s often-constrained timeline.    

 

Accordingly, the District intends to plan for and pursue implementation within the specific drainage areas enumerated below while also developing and pursuing other opportunities as they arise.  With respect to the latter, there will be several project development elements to ensure transparency and public accountability:

 

(a) The District will continue to work in partnership with the LGUs in the subwatershed to complete a more detailed study of the hydrologic and hydraulic conditions in the subwatershed to determine how District and LGU objectives can best be reconciled and advanced through partnership projects. For example, the District currently is working in coordination with the cities of Hopkins, St. Louis Park, Edina and Minneapolis and the MPRB to explore opportunities to partner on the regional treatment of stormwater runoff volumes and loads within priority subwatersheds. The City of Minneapolis has identified three specific priority projects for review and consideration for partnership with the District.  The cost share between project partners would be determined during the development of feasibility studies for each project.   These are:

 

  • Flood area 29-30, located in subwatershed unit MC-129.  This area drains to Lake Harriet, but has been considered in the past for redirection of some flow to the Creek.  If the volume and load reduction study identifies this as a feasible option, it may be possible to coordinate improvements to manage stormwater in that area with the stream restoration project already identified for Reach 12.  The estimated total cost of this project is $7.4 million.

 

  • Flood area 26 “C”, located in subwatershed unit MC-147.   Stormwater ponding and storm sewer upgrades are being considered for this third phase of projects in this flood area.  The estimated total cost of this project is $1.8 million.

 

  • Flood area 21-22, located in subwatershed unit MC-170.   This area is in the direct drainage area of Lake Hiawatha, and includes stormwater upgrades and combined sewer separation projects.  The estimated total cost of this project is $7.8 million.

 

For any significant implementation actions, whether the District pursues it in partnership or otherwise, a focused feasibility study will be prepared to examine feasibility and cost-effectiveness.  The study will be made publicly available and presented to the Board of Managers at a public meeting with the availability for public comment.

 

(b) As described earlier in this plan, each year, for budget and levy purposes, the District will review the status of its capital program in a public forum with opportunity for public input.  Proposed revisions to the District’s 10-year CIP will be provided to Hennepin and Carver Counties and all cities wholly or partly within the District.  At its budget and levy hearing, the District Board of Managers will make budgeting decisions that will set overall parameters for spending under this capital project 5.8.5 and set specific project implementation priorities for the upcoming fiscal year.

 

(c) Before expending levied funds on the design or construction of an implementation action, the Board will distribute design plans and provide public notice for a public hearing and project ordering in accordance with Minnesota Statutes §103B.251.  If the proposed work will exceed $300,000, the District will afford the additional procedures set forth in section 6.8 of the watershed plan (page 84).

 

Outcome

Minimized new pollutant loads conveyed by runoff and generated within Minnehaha Creek; minimized new volumes generated by new development; protection of stream base flows and wetland and surficial groundwater hydrology; wetland restorations; conservation of high-value native vegetation and habitat.

Estimated

Cost

Minnehaha Creek Subwatershed Volume and Load Reduction Study

$200,000

Project 1:  Improvements in MC-129.  Funding source is City of Minneapolis and District capital levy.

$2,299,800

Project 2:  Improvements in MC-147.  Funding source is City of Minneapolis and District capital levy.

$3,533,000

Project 3: Improvements in MC-170.  Funding source is City of Minneapolis and District capital levy.

$2,440,600

Project 4:  Improvements in MC-58.  Funding source is District capital levy.

$435,200

Project 5:  Improvements in MC-70-75.  Funding source is District capital levy.

$487,600

Project 6: Improvements in MC-95.  Funding source is District capital levy.

$2,221,500

Project 7: Improvements in MC-97.  Funding source is District capital levy.

$1,504,500

Project 8: Improvements in MC-134.  Funding source is District capital levy.

$485,400

Project 9: Improvements in MC-135.  Funding source is District capital levy.

$1,340,200

Project 10: Improvements in MC-139.  Funding source is District capital levy.

$511,000

Project 11: Improvements in MC-140.  Funding source is District capital levy.

$1,493,400

Project 12: Improvements in MC-146.  Funding source is District capital levy.

$564,300

Project 13: Improvements in MC-150.  Funding source is District capital levy.

$362,100

Project 14: Improvements in MC-151.  Funding source is District capital levy.

$524,700

Project 15: Improvements in MC-152.  Funding source is District capital levy.

 

Overall Implementation Estimate:

$678,500

 

 

$19,081,800

Schedule

2008:  Complete volume and load reduction study

2008:  Identify and construct improvements in MC-129

2009:  Identify and construct improvements in MC-147

2011:  Identify and construct improvements in MC-170

2012:  Identify and construct improvements in MC-134

2013:  Identify and construct improvements in MC-95

2014:  Identify and construct improvements in MC-97

2015:  Identify and construct improvements in MC-146

2015:  Identify and construct improvements in MC-70-75

2016:  Identify and construct improvements in MC-58

Unscheduled:  Identify and construct improvements in MC-152, MC-139, MC-150, MC-135, MC-140, MC-151; identify and construct improvements otherwise developed through described procedures.

5.8.6 Land Conservation

ProjectMinnehaha Creek Subwatershed Land Consercation Activities
DescriptionImplementation of Land Conservation program activities in the Minnehaha Creek subwatershed, including but not limited to acquisition of conservation easements or fee title to land as well as facilitating partnerships, encouraging conservation planning and activities, providing technical assistance, and education and outreach.
NeedThe Land Conservation Program is an integral strategy to achieving the goals in this subwatershed plan. Land conservation activities help to maintain and improve ecologic integrity, surface and groundwater quantity and quality, wetlands integrity, and streambank stability. High priority areas are located in this subwatershed, including areas with high ecological values. Conservation of key land cover types may be beneficial to reducing runoff and associated pollutant transport, preserving high-infiltration areas, conserving native vegetation, conserving habitat and natural resource corridors, and improving ecologic integrity.
OutcomeMinimized new pollutant loads conveyed by runoff; protection of wetland and surficial groundwater hydrology; wetland restorations; conservation of high-value native vegetation and habitat.
Estimated Cost and Funding
Estimated cost to achieve conservation goals in the Minnehaha
Creek subwatershed 2007-2017
$4,215,000
District capital levy
ScheduleImplement both proactively and as opportunities arise during the period 2007-2017

5.8.7 Browndale Dam Scour Repair

ProjectBrowndale Dam Scour Repair
DescriptionRestore eroded base of dam and scour hole to prevent future structural damage
NeedThe Browndale Dam is a historic structure that lies at the outlet of the Mill Pond in the City of Edina. During the Plan Review process, the City of Edina solicited the involvement of MCWD in addressing erosion and scour issues occurring at the base of the dam. The City has proposed to design and implement structural improvements to counteract undercutting of the dam sill and stabilize a large scour hole at the downstream base of the structure. The District will work collaboratively with the City of Edina construct improvements. The specific share of construction cost as well as ongoing maintenance costs associated with these improvements would be determined by cooperative agreement prior to implementation of this project.
OutcomeProtection of public health and safety; stabilized streambed to reduce erosion
Estimated Cost and FundingFunding source for this project is the District capital levy. The specific share of construction cost as well as ongoing maintenance costs associated with these improvements would be determined by cooperative agreement prior to implementation of this project.$50,500
Schedule

2007 Design, cooperative agreement

2008 Construction

5.8.8 Maintenance Projects

The District is responsible for sediment removal from several ponds in the subwatershed. Sediment has been recently removed from some of these ponds. They should be surveyed in 2008 to determine if maintenance is necessary.

Table 24.  Estimated pond maintenance costs in the Minnehaha Creek subwatershed.

StructureEstimated CostNotes
Twin Lakes Park PondDependant on outcome of surveySurvey in 2008
Cedar Meadows PondSurvey in 2008
Lake Calhoun PondsSurvey in 2008
Lake Nokomis PondsSurveyed in 2005; resurvey in 2008
Pamela Park PondsSurvey in 2008

5.8.9 Other Projects

This Plan identified the need to consider additional projects not included in the prioritized 2007-2017 CIP. These include regional infiltration opportunities in subwatershed units MC-140, 147, and 151 (see Section 5.8.5 above); four priority reaches of Minnehaha Creek as noted above; and dredging Longfellow Lagoon to remove accumulated fine sediments. The Board may consider such projects during the time frame of this Plan if funds are available.

ProjectLongfellow Lagoon Dredging
DescriptionDredging fine sediment accumulated in the Longfellow Lagoon impoundment
NeedThe Stream Assessment identified a sediment delta in Longfellow Lagoon. Fine sediments drop out and accumulate in this impoundment. To preserve channel conveyance and improve aesthetics, consideration should be given to dredging the lagoon.
OutcomeImproved aesthetics, habitat, and water quality
Estimated Cost and FundingDesign, construction, project management. Funding source for this project is the District capital levy.$114,100
ScheduleOne Year Prior to Construction: Design, cooperative agreementNo Year Assigned: Construction of stream restoration

 

ProjectReach 2 Restoration
DescriptionStreambank restoration, buffer reestablishment, enhancement of in-stream habitat features
NeedThis reach extends from just above Minnehaha Falls to the Hiawatha Avenue weir. It contains a few streambank erosion sites and locations where retaining walls have failed. Fish spawning habitat is poor as fine sediment is deposited behind the weir in the Longfellow Lagoon. The riparian corridor is poor or nonexistent and in need of improvement. The reach scored a 4.3 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features.
OutcomeStabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0.
Estimated Cost and FundingDesign, construction, project management, vegetation management contract. Funding source for this project is the District capital levy.$190,200
ScheduleOne Year Prior to Construction: Design, cooperative agreementNo Year Assigned: Construction of stream restoration
ProjectReach 11 Restoration
DescriptionStreambank restoration, buffer reestablishment, enhancement of in-stream habitat features
NeedThis reach extends from Lyndale Avenue to Logan Avenue S. It contains storm sewer outfalls that require repair or improvement, and unpaved trails on the right bank that may exacerbate erosion. The riparian corridor is a mix of turf grass maintained to an eroding creek edge and stable banks with riparian tree and shrub growth. The reach scored a 5.7 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due lack of in-stream fish and invertebrate habitat. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features.
OutcomeStabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0.
Estimated Cost and FundingDesign, construction, project management, vegetation management contract. Funding source for this project is the District capital levy.$1,179,500
Schedule

One Year Prior to Construction: Design, cooperative agreement

No Year Assigned: Construction of stream restoration

ProjectReach 18 Restoration
DescriptionStreambank restoration, buffer reestablishment, enhancement of in-stream habitat features
NeedThis reach extends from West 44th Street to Soo Line Railroad Bridge. The riparian corridor is a mix of turf grass maintained to an eroding creek edge and stable banks with riparian tree and shrub growth. Establishing native vegetation on streambanks and in buffers would help stabilize eroding streambanks. The reach scored a 6.2 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to lack of in-stream fish and invertebrate habitat and poor riparian conditions. The project would evaluate the replacement of existing 44th Street bridge grade control riffle would restore the stream to a more free-flowing condition.
OutcomeStabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 7.0.
Estimated Cost and FundingDesign, construction, project management, vegetation management contract. Funding source for this project is the District capital levy.$443,900
Schedule

One Year Prior to Construction: Design, cooperative agreement

No Year Assigned: Construction of stream restoration

ProjectReach 29 Restoration
DescriptionStreambank restoration, buffer reestablishment, enhancement of in-stream habitat features
NeedThis reach extends from Bridge Street to the I-494 west off ramp. The riparian corridor is a mix of turf grass maintained to an eroding creek edge and stable banks with riparian tree and shrub growth. Invasive species dominate the riparian zone. Invasive species should be eradicated and native riparian cover established or enhanced throughout the reach. The reach scored a 4.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to lack of in-stream fish and invertebrate habitat. Meander reconstruction could improve stream complexity and improve in-stream habitat conditions.
OutcomeStabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0.
Estimated Cost and FundingDesign, construction, project management, vegetation management contract. Funding source for this project is the District capital levy.$862,400
Schedule

One Year Prior to Construction: Design, cooperative agreement

No Year Assigned: Construction of stream restoration

5.8.10 Taft-Legion Lake Regional Volume and Load Reduction

Project

Taft-Legion Lake Regional Volume and Load Reduction

Description

The City of Richfield proposed the collaborative implementation of an improvement project  that, when completed, will provide treatment for urban stormwater runoff discharging into Taft Lake and Legion Lake, subsequently improving the quality of water discharged from the City of Richfield’s boundaries to Lake Nokomis and ultimately Minnehaha Creek.

 

Project plans include several different elements working in combination to achieve water-quality and volume-management improvements. Elements under consideration include:

 

Irrigation:    Stormwater runoff will be withdrawn from stormwater basins and applied via irrigation to adjacent park land at Legion and/or Taft Lakes.

 

Infiltration:  The infiltration system will operate concurrent with the proposed irrigation system.  Depending on seasonal rainfall variation, if additional water is available to be withdrawn from the enhanced basins/ponds, water will be directed to underground infiltration systems in park land surrounding Taft Lake and Legion Lake.

 

Flocculation Enhanced Stormwater Pond:  An existing road around the north end of Taft Lake will be removed to facilitate the construction of a stormwater pond with a flocculation system that will remove dissolved pollutants from storm sewer runoff that’s delivered to the system.

 

Flocculation of Water from Taft Lake:  In addition to treating runoff delivered to a constructed stormwater pond on the north side of Taft Lake the flocculation system will have the capacity to treat water withdrawn from adjacent stormwater ponds and/or the hypolimnion of Taft Lake, removing dissolved pollutant loads, before it’s discharged back into Taft Lake.

 

Natively Planted Lakeshore Buffers:  Native lakeshore buffers will be established in select areas surrounding Legion Lake.

 

Pre-Treatment of Runoff to Legion Lake:  A series of sedimentation ponds and/or enhanced grit-removal chambers will be installed to remove sediment and phosphorus loads prior to being discharged into Legion Lake.

 

Stakeholder engagement and educational efforts: Efforts to develop a comprehensive outreach, education and stakeholder engagement plan will be integrated into the design of each element of the project, and communications tools will be used to support citizens’ understanding of the purpose and function of the project. 

Need

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Implementation of this project will address several goals of the 2007 MCWD Comprehensive Water Resource Management Plan and enable the City of Richfield to meet its various obligations to reduce annual stormwater volumes and pollutant loads.

 

MCWD goals addressed include: 

 

MCWD Goal 1: Abstraction/Filtration.  Promote abstraction and filtration of surface water where feasible for the purposes of improving water quality and increasing groundwater recharge throughout the watershed.

 

MCWD Goal 2: Ecological Integrity.  Promote activities that maintain, support and enhance floral, faunal quantity and ecological integrity of upland and aquatic resources throughout the watershed.

 

MCWD Goal 3.  Water Quality.  Preserve, maintain and improve aesthetic, physical, chemical and biological composition of surface waters and groundwater within the District

 

MCWD Goal 5.  Water Quantity.  Maintain or reduce existing flows from drainage within the watershed to decrease the negative effects of stormwater runoff and bounce from existing and proposed development as well as provide low flow augmentation to surface waters.

 

MCWD Goal 6.  Shorelines and Streambanks.  Preserve the natural appearance of shoreline areas.

 

MCWD Goal 9.  Education and Communications.  Enhance public participation and knowledge regarding District activities and provide informational and educational material to municipalities, community groups, businesses, schools, developers, contractors and individuals.

 

Implementation of the various project elements also is expected to address the impairment of Lake Nokomis by excessive nutrients, as described in the Total Maximum Daily Load study for the lake.  The study determined that annual phosphorus loading to the lake from stormwater runoff generated by the City of Richfield and the Metropolitan Airports Commission must be reduced by 16 pounds.

Outcome

This project is designed and intended to provide both volume and phosphorus load reductions as shown in the table below:

 

Project Element 

Water Volume Reduction (ac-ft/yr) 

P Load Reduction (lbs/yr) 

Water Reuse Irrigation System (Legion Lake)

10-40

12-50

Stormwater Infiltration (Legion/Taft Lake) and Ponding (Taft)

120-240

125-240

Mechanical Grit Chambers (Legion)

-

0-24

Native Lakeshore Buffer (Legion)

minor

2-8

Flocculation System (Taft)

-

40-160

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Estimated

Cost

 

 

Project Element 

 Estimated Capital Cost  

Water Reuse Irrigation System (Legion Lake)

 $                                        300,000

Stormwater Reuse Infiltration (Legion/Taft Lake) and Ponding (Taft)

 $                                    1,140,000

Proprietary Grit Chambers (Legion)

 $                                        300,000

Native Lakeshore Buffer (Legion)

 $                                          60,000

Flocculation System (Taft)

 $                                        900,000

TOTAL CAPITAL COST 

 $                                    2,700,000

Annual Operation, Maintenance and Monitoring

 $                                        150,000

TOTAL O&M Cost (20 year life) 

 $                                    3,000,000

 

To avoid or minimize a levy increase, if the project is ordered, consideration will be given to funding the $2,700,000 necessary for construction through a combination of upfront city financing of capital costs and a reduced, recurring annual District ad valorem levy over 20 years.  Other alternative frameworks and sources of funding, such as grants, also will be considered.

 

$2,700,000

 

 

 

Schedule

Implementation between 2012 - 2013

5.9 Summary

The following tables summarize the proposed implementation action items and their relationship to overall District the problems and issues identified in Section 3.0 above, the metrics by which the District will be evaluating progress toward resolving those issues and problems, the estimated District cost of implementing these actions, and anticipated implementation schedule.

Table 25.  Problems and issues identified in the Minnehaha Creek subwatershed and actions proposed to address them.

 

Problem or Issue

Actions in Implementation Plan

Degree of Improvement

Water Quality

The water quality in Minnehaha Creek as measured by total phosphorus and TSS concentrations is comparable to the MPCA’s ecoregion guidelines.  Phosphorus and sediment loads in Minnehaha Creek increase upstream to downstream, although the impoundments at the major grade controls act as settling basins and trap some of the pollutants and sediment.  Average chloride concentrations are generally lower than state standards, and dissolved oxygen concentrations are generally sustained at levels sufficient to maintain aquatic life.  Monitoring for e. coli bacteria shows increasing concentrations from upstream to downstream at levels sometimes exceeding state standards.

  • A series of stream restoration projects to stabilize streambanks to reduce pollutant loading from bank erosion, improve buffers, and increase habitat
  • Actions to increase infiltration in the subwatershed to reduce pollutant loading conveyed from stormwater runoff
  • Continued monitoring of Minnehaha Creek for various parameters including bacteria
  • A diagnostic study of Minnehaha Creek to evaluate potential to improve water quality and ecologic integrity through in-stream and near-stream restorations 

Implementation of actions in this Plan would maintain or improve water quality and ecologic integrity in Minnehaha Creek

Six lakes in the subwatershed have been designated Impaired Waters on the state’s 303(d) list due to an excess of nutrients.  The District has petitioned to remove two of those lakes.  The District is preparing Total Maximum Daily Load (TMDL) studies, including plans to reduce phosphorus loads into the lakes, for Nokomis, Diamond, Hiawatha, and Powderhorn Lakes.

  • The draft TMDLs identify potential improvement projects that have been incorporated into this Plan.
  • Continue monitoring the lakes to assess progress. 

Implementation of all the actions in the phosphorus load reduction plans for the lakes would theoretically reduce in-lake P concentrations, improve water clarity, and meet District goals and state and federal water quality standards.

 

The HHPLS established and the Lake Hiawatha TMDL assumes an in-creek total phosphorus concentration goal of 80 ug/L.   The HHPLS estimated that achieving this goal would require a 15 percent reduction in phosphorus loading to the creek from the entire subwatershed, excluding the Chain of Lakes and Lake Nokomis lakesheds.  However, not enough is known about in-stream processes and sources to partition that load reduction between loading from runoff and loading from in-stream sources such as streambank erosion, internal loading, riparian wetlands, etc.

  • Rules will be amended to require more stringent pollutant load reduction on new development and redevelopment, including adding an abstraction requirement to reduce pollutant loading from runoff.
  • Cooperatively construct regional infiltration improvements to mitigate impact of new runoff from development and to reduce pollutant loading from existing development.
  • A diagnostic study of Minnehaha Creek to evaluate potential to improve water quality and ecologic integrity through in-stream and near-stream restorations. 
  • Implementation of actions in this Plan would maintain or improve water quality and ecologic integrity in Minnehaha Creek and theoretically reduce pollutant loading conveyed to Lake Hiawatha from the creek, improving its water quality.
  • Would depend on ability of developers to incorporate adequate BMPs on their projects and properly maintain them to sustain removal efficiencies.
  • Depends on ability to develop cooperative or collaborative improvements.
 

Development in the subwatershed has resulted in increased stormwater volumes conveying nutrients and sediment to the lakes and to Minnehaha Creek.  Significant efforts and investments by the District and the local governments have been made to improve water quality in the lakes through improvement projects, restorations, and nonstructural BMPs such as education and street sweeping.  As a result Brownie Lake, Cedar Lake, Lake of the Isles, and Lake Calhoun meet or exceed their water quality goals.

Rules will be amended to require more stringent pollutant load reduction on new development and redevelopment, including adding an abstraction requirement to reduce pollutant loading from runoff.

 

  • Implementation of actions in this Plan would maintain or improve water quality and ecologic integrity in Minnehaha Creek and the lakes that currently meet or exceed their water quality goals.
  • Would depend on ability of developers to incorporate adequate BMPs on their projects and properly maintain them to sustain removal efficiencies.
  • Depends on ability to develop cooperative or collaborative improvements.

Development, redevelopment, and reconstruction in the subwatershed may provide opportunities to obtain a net decrease in volume of stormwater runoff, nutrient, and TSS loads.

  • Rules will be amended to require more stringent pollutant load reduction on new development and redevelopment, including adding a volume management requirement.
  • Would depend on ability of developers to incorporate adequate BMPs on their projects and properly maintain them to sustain removal efficiencies.
  • Cooperatively construct regional infiltration improvements to mitigate impact of new runoff from development.
  • Depends on ability to develop cooperative or collaborative improvements.
 
   

Water Quantity

Drainage is conveyed through the subwatershed through a network of storm sewers, ditches, wetlands and lakes that discharge to Minnehaha Creek.  The Minnehaha Creek Stream Assessment identified 35 locations on the creek with significant erosion or bank failure, and numerous locations with less severe erosion.   Channel bank stability is stressed by “flashy” storm discharges which produce high velocities and rapid increases and decreases in stage coupled with poor riparian zone management and numerous storm sewer outfalls.

  • A series of stream restoration projects to stabilize streambanks to reduce pollutant loading from bank erosion, improve buffers, and increase habitat.
  • A program to collaboratively construct spot repairs on reaches where full-scale restoration is not planned at this time.

 

Completion of projects would repair existing erosion and stabilize the creek where it is most at risk for future erosion.

Development of the subwatershed has resulted in increased stormwater volumes and flow peaks and reduced infiltration and base flow in Minnehaha Creek.  Development, redevelopment, and reconstruction in the subwatershed may provide opportunities to achieve a net decrease in volume of stormwater runoff, nutrient and TSS loads conveyed to those water resources.

  • Rules will be amended to require more stringent pollutant load reduction on new development and redevelopment, including adding a volume management requirement.
  • Would depend on ability of developers to incorporate adequate BMPs on their projects and properly maintain them to sustain removal efficiencies.
  • Cooperatively construct regional infiltration improvements to mitigate impact of new runoff from development.
  • Depends on ability to develop cooperative or collaborative improvements.
 
   

Limitations on discharges from the Grays Bay dam, reduced infiltration and baseflow, multiple impoundments on the creek, and channel overwidening to accommodate high flows leads to extended periods when the flows and depths in the creek channel are insufficient for recreation and severely stress aquatic life.

  • A stream diagnostic and biotic integrity TMDL to identify stressors and the most effective ways to reduce and mitigate for them
  • A series of stream restoration projects to stabilize streambanks to reduce pollutant loading from bank erosion, improve buffers, and increase habitat.
  • A program to collaboratively construct spot repairs on reaches where full-scale restoration is not planned at this time.

 

Completion of projects would repair existing erosion and stabilize the creek where it is most at risk for future erosion, and improve habitat to reduce low-flow stress on aquatic life.

Several landlocked subwatershed units and individual subbasins are present in the subwatershed, primarily in Minnetonka and St. Louis Park.  As identified in the HHPLS, several of these subwatersheds or basins are being considered by the cities for outletting, altering local hydrology and potentially creating downstream volume or water quality impacts.  Within these landlocked basins, any future development or redevelopment should minimize creation of new stormwater volumes.

Cities are prohibited from adding outlets to landlocked basins, and must provide for adequate storage and volume control.

 

Completed as LGUs complete their local plans.

 

Impoundments and grade control structures along the creek cause sediment to be deposited and accumulate, limiting habitat values.

A diagnostic study of Minnehaha Creek to evaluate potential to improve water quality and ecologic integrity through in-stream and near-stream restorations.

Implementation of actions in this Plan would maintain or improve water quality and ecologic integrity in Minnehaha Creek

The HHPLS identified multiple locations within the subwatershed that are predicted to overtop during the 100 year event, including city streets, trails, and driveways.

LGUs directed to evaluate these locations as part of their local water management planning.

Completed as LGUs complete their local plans.

The HHPLS identified several locations where for both existing and future conditions, higher velocities than desired may result in erosion at outlets or culverts.  

LGUs directed to evaluate these locations as part of their local water management planning.

Completed as LGUs complete their local plans.

Wetlands

The subwatershed includes several wetlands with high to exceptional vegetative diversity, fish and wildlife habitat and aesthetic values that need to be protected.

  • Key Conservation Areas identified that include high-value wetlands.  Some of these areas are identified as District priorities for continued implementation of the Land Conservation Program, and thus the District would proactively look for opportunities to conserve these resources. The Capital Improvement Program includes funds for Land Conservation Activities.   In all key areas, LGUs are required to include in their local plans strategies for conserving these values.
  • Ongoing effort that is dependant on property owner willingness to pursue conservation, District budget and staff capacity, and LGU plan completion.
  • Rules will be amended to establish management standards based on management classification for impacts to wetlands from development and redevelopment.
  • Implementation of revised rules would help minimize future impacts to the highest-value wetlands while still providing a measure of protection to those that provide mainly downstream resource protection.
 
   

Most of the wetlands in the subwatershed have been impacted by development, as indicated by the lack of wetlands with exceptional to high vegetative diversity given the size of the subwatershed.   Degraded wetlands with high to moderate restoration potential should be considered for protection and restoration.

  • Wetland restorations will be evaluated as part of the creek diagnostic
  • Wetlands identified as being of high to moderate wetland potential would be managed according to a Manage 1 wetland classification if they have been assessed as a Manage 2 or 3.   This would minimize further degradation that might make future restoration more difficult or costly.

An initial effort that identifies for restoration those wetlands that would result in improvement to water quality in the lakes.   This would begin to mitigate wetland losses from past development and help to increase the quantity and quality of wetlands present.

Ecological Integrity

Most of the subwatershed is fully developed at urban and suburban densities, with opportunities for the conservation of ecological integrity being primarily within the creek corridor or some larger wetland complexes.

 

Key Conservation Areas identified that include high-value wetlands.  Some of these areas are identified as District priorities for continued implementation of the Land Conservation Program, and thus the District would proactively look for opportunities to conserve these resources. The Capital Improvement Program includes funds for Land Conservation Activities.   In all key areas, LGUs are required to include in their local plans strategies for conserving these values.

Ongoing effort that is dependant on property owner willingness to pursue conservation, District budget and staff capacity, and LGU plan completion.

Fish surveys have been completed by the DNR on the major lakes in the subwatershed, and the fisheries are actively managed through stocking.

  • Continue to work cooperatively with the DNR, MPRB, and Three Rivers on fisheries issues.
  • Support the fisheries through the improvement of water quality.

Depends on response of natural community to habitat improvement.

A fish survey conducted by the DNR on Minnehaha Creek found mostly lake species with few adults, indicating a lack of suitable habitat and few refuges for overwintering and low flow periods.

  • Support the DNR in its management efforts. 
  • Evaluate milfoil management as part of internal load management diagnostic and feasibility study.
  • A stream diagnostic and biotic integrity TMDL to identify stressors and the most effective ways to reduce and mitigate for them

 

Depends on the extent of infestation.  If control of milfoil and other invasive aquatic vegetation will help achieve internal phosphorus load reduction goals, then a significant improvement can be had through chemical or other control.  If control would not benefit lake water quality, then there would be no improvement.

Macroinvertebrate communities in Minnehaha Creek are limited by frequent wetland and impounded reaches, water quality, and lack of habitat.

  • A stream diagnostic and biotic integrity TMDL to identify stressors and the most effective ways to reduce and mitigate for them.
  • A series of stream restoration projects to stabilize streambanks to reduce pollutant loading from bank erosion, improve buffers, and increase habitat.

 

Depends on response of natural community to habitat improvement.

Eurasian watermilfoil is present in many of the lakes, and the Minneapolis Park Board performs weed cutting on the Chain of Lakes to better support swimming and boating.

  • Support the DNR and MPRB in their management efforts. 
  • Evaluate milfoil management as part of internal load management diagnostic and feasibility study.

Depends on the extent of infestation.  If control of milfoil and other invasive aquatic vegetation will help achieve internal phosphorus load reduction goals, then a significant improvement can be had through chemical or other control.  If control would not benefit lake water quality, then there would be no improvement.

Groundwater

Development of the subwatershed has resulted in increased stormwater volumes and flow peaks and reduced infiltration and base flow in Minnehaha Creek.  Development, redevelopment, and reconstruction in the subwatershed may provide opportunities to decrease stormwater runoff volumes and increase infiltration

  • Amend rules to require infiltration or abstraction of the first one inch of rainfall on new permitted development and redevelopment.
  • Infiltration on site will assist in preventing further modification of surficial groundwater recharge and help to maintain wetland hydrologic regimes.
  • Identify a network of surficial aquifer monitoring wells across the watershed, monitor groundwater levels and quality.
  • Implementation of monitoring network will fill data gap and allow for identification of trends.
  • Identify baseflow in Minnehaha Creek and monitor for trends.
  • Identification of baseflow will fill  data gap, allow for identification of trends, and improve understanding of hydrology and hydraulics of Minnehaha Creek.
 
   
   

Ongoing flow monitoring in Minnehaha Creek suggests that some reaches of the creek are losing flow to groundwater, possibly contributing to periods of low or intermittent flow.

 

  • Amend rules to require infiltration or abstraction of the first one inch of rainfall on new permitted development and redevelopment.
  • A stream diagnostic and biotic integrity TMDL to identify stressors and the most effective ways to reduce and mitigate for them

Depends on outcome of study and recommendations

Seeps and springs are present in the subwatershed, mainly in the limestone cliffs of the Gorge.  The most prominent spring is Camp Coldwater Spring.  Hydrologic analysis and monitoring conducted at the time the Minnesota Department of Transportation proposed to construct a new highway interchange nearby indicate this historic spring is sensitive to impacts in its groundwatershed

  • Amend rules to require pretreatment of stormwater discharged to wetlands or infiltration areas in the areas of high aquifer sensitivity.
  • Establish a new District rule that requires an additional level of analysis and review of permitted development and redevelopment where there is a potential for development to adversely impact groundwater connected to a surface water feature.

Will help minimize future impacts to groundwater and provide for proactive management rather than reactive

The extensive wetlands in the upper subwatershed were identified in the FAW as either discharge wetlands or combination recharge-discharge wetlands.  It will be critical to maintain or increase infiltration rates in the upper subwatershed to help maintain hydrology to these wetlands.  Wetlands in the lower subwatershed are mainly recharge or combination wetlands.  The hydrology of these wetlands depends on maintaining local flow patterns and rates

  • Amend rules to require infiltration or abstraction of the first one inch of rainfall on new permitted development and redevelopment.
  • Identify a network of surficial aquifer monitoring wells across the watershed, monitor groundwater levels and quality.
  • Promote Better Site Design (Low Impact Development) principles for new development that mimic predevelopment hydrologic regime.

 

Infiltration on site will assist in preventing further modification of surficial groundwater recharge and help to maintain wetland hydrologic regimes.

Much of the subwatershed is very highly or highly sensitive to aquifer impacts, including the Minnehaha Creek corridor

  • Amend rules to require pretreatment of stormwater discharged to wetlands or infiltration areas in the areas of high aquifer sensitivity.
  • Establish a new District rule that requires an additional level of analysis and review of permitted development and redevelopment where there is a potential for development to adversely impact groundwater connected to a surface water feature.

Will help minimize future impacts to groundwater and provide for proactive management rather than reactive

Wellhead Protection Areas have been identified for the cities of Edina, Minnetonka and St. Louis Park within this subwatershed.  Stormwater management within those areas should be coordinated with wellhead protection plans

  • Stormwater and groundwater management within those areas will be coordinated with wellhead protection plans.
  • Will help minimize future impacts to drinking water and provide for proactive management rather than reactive
 

Table 26.  Summary of metrics to be used in evaluating progress toward Minnehaha Creek subwatershed goals.

Objective

Metric

Existing

Desired

Location

Water Quality

Phosphorus Loading (lbs annually)

665

(Ultimate)

562

Lake Harriet

Phosphorus Loading (lbs annually)

908

(Ultimate)

599

Lake Nokomis

Phosphorus Loading (lbs annually)

11,126

(Ultimate)

10,038

Lake Hiawatha

Phosphorus Loading (lbs annually)

486

(Ultimate)

265

Diamond Lake

Phosphorus Loading (lbs annually)

267

(Ultimate)

90

Powderhorn Lake

Water Quantity

Volume Reduction (Acre-feet)

 

1,298

Watershed-wide

1.5 year discharge (cfs)

219.7

219.7

Watershed-wide

100 year discharge (cfs)

676.2

676.2

Watershed-wide

Ecologic Integrity

Index of Biotic Integrity

3.51

 (F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 30

N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 29

N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 28

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 27

 3.76

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 26

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 25

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 24

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 23

N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 22

 4.78

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 21

 5.39

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 20

N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 19

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 18

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 17

 4.88

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 16

N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 15

 5.56

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 14

 4.00

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 13

 5.31

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 12

 5.13

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 11

 3.96

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 10

 5.08

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 9

 4.24

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 8

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 7

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 6

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 5

N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 4

 N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 3

N/A

Above MPCA impairment threshold

Minnehaha Creek Reach 2

 4.26

(F-IBI)

Above MPCA impairment threshold

Minnehaha Creek Reach 1

Stream Visual Assessment Protocol

6.3

5.0 or 1+ existing

Minnehaha Creek Reach 30

4.8

5.0 or 1+ existing

Minnehaha Creek Reach 29

7.0

5.0 or 1+ existing

Minnehaha Creek Reach 28

7.5

5.0 or 1+ existing

Minnehaha Creek Reach 27

6.3

5.0 or 1+ existing

Minnehaha Creek Reach 26

6.4

5.0 or 1+ existing

Minnehaha Creek Reach 25

2.0

5.0 or 1+ existing

Minnehaha Creek Reach 24

4.1

5.0 or 1+ existing

Minnehaha Creek Reach 23

6.1

5.0 or 1+ existing

Minnehaha Creek Reach 22

7.0

5.0 or 1+ existing

Minnehaha Creek Reach 21

2.0

5.0 or 1+ existing

Minnehaha Creek Reach 20

6.1

5.0 or 1+ existing

Minnehaha Creek Reach 19

6.0

5.0 or 1+ existing

Minnehaha Creek Reach 18

2.0

5.0 or 1+ existing

Minnehaha Creek Reach 17

5.8

5.0 or 1+ existing

Minnehaha Creek Reach 16

5.8

5.0 or 1+ existing

Minnehaha Creek Reach 15

5.6

5.0 or 1+ existing

Minnehaha Creek Reach 14

7.1

5.0 or 1+ existing

Minnehaha Creek Reach 13

3.8

5.0 or 1+ existing

Minnehaha Creek Reach 12

5.7

5.0 or 1+ existing

Minnehaha Creek Reach 11

6.9

5.0 or 1+ existing

Minnehaha Creek Reach 10

5.1

5.0 or 1+ existing

Minnehaha Creek Reach 9

5.1

5.0 or 1+ existing

Minnehaha Creek Reach 8

4.0

5.0 or 1+ existing

Minnehaha Creek Reach 7

2.0

5.0 or 1+ existing

Minnehaha Creek Reach 6

3.0

5.0 or 1+ existing

Minnehaha Creek Reach 5

4.7

5.0 or 1+ existing

Minnehaha Creek Reach 4

2.0

5.0 or 1+ existing

Minnehaha Creek Reach 3

4.3

5.0 or 1+ existing

Minnehaha Creek Reach 2

7.6

5.0 or 1+ existing

Minnehaha Creek Reach 1

 

Key Conservation Areas conserved (acres)

 

98

Watershed-wide

Wetlands

Wetland Acreage

3,874.0

3,874.0 or greater

Watershed-wide

1,035.3

1,035.3 or greater

Preserve

575.6

575.6 or greater

Manage 1

314.7

314.7 or greater

Manage 2

735.5

735.5 or greater

Manage 3

Table 27.  Summary of Minnehaha Creek subwatershed implementation program.

Item

Description

Estimated Cost

Schedule

Section 3.0

MCWD Capital Projects

1

Stream restorations

$944,100

2014

3.1.1, 3.1.3, 3.2.1, 3.2.2, 3.2.3,3.2.5, 3.3.1, 3.4.3, 3.4.4

$451,000

2015

$654,800

2012

$967,600

2007

$877,700

2015

$1,380,100

2016

$896,000

2012

$1,203,400

2010

2

Minnehaha Falls Glen Restoration

$1,795,300

2008

 

3

Lake Nokomis internal load management

$342,100

2007

3.2.5

4

Regional infiltration

$410,100

2013

3.1.1, 3.1.2, 3.1.3, 3.1.5, 3.2.2, 3.2.4, 3.5.1, 3.5.2, 3.5.3, 3.5.4

$485,400

2012

$3,533,000

2009

$2,440,600

2011

$2,299,800

2008

$2,221,500

2013

$1,051,900

2015

$915,400

2012

$435,200

2016

$1,504,500

2014

MCWD Data Acquisition/Study

1

Minnehaha Creek Subwatershed Volume and Load Reduction Study

$200,000

 

2008

3.1.1, 3.1.2, 3.1.4, 3.2.1, 3.2.2, 3.2.7, 3.3.3, 3.4.3, 3.4.4, 3.5.1

2

Develop infiltration/filtration strategies appropriate to wellhead protection areas and areas of groundwater sensitivity

Part of watershed-wide study

2008

3.1.2, 3.1.4, 3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.2.6, 3.2.7, 3.3.1, 3.3.3, 3.4.1, 3.5.1, 3.5.2, 3.5.3, 3.5.4

3

Identify key indicator species, evaluate habitat, and develop conservation strategies

Part of watershed-wide study

2010 and ongoing

3.3.1, 3.3.2, 3.3.3, 3.4.1, 3.4.3, 3.4.4

MCWD Land Conservation Program

1

Undertake land conservation efforts in accordance with Figure 19

$4,215,000

Part of ongoing watershed-wide program

3.1.2, 3.1.4, 3.2.2, 3.3.1, 3.3.2, 3.3.3, 3.4.1, 3.4.3, 3.4.4, 3.5.1

MCWD Regulatory Program

1

Amend District Rules to increase stormwater management requirements for new development and redevelopment

Part of watershed-wide effort

2007-2009

3.1.1 - 3.1.4, 3.4.4

2

Amend District Rules to require abstraction of 1” of rainfall on permitted development and redevelopment

Part of watershed-wide effort

2007-2009

3.1.1 - 3.1.4, 3.2.1, 3.2.2, 3.2.4, 3.2.5, 3.2.6, 3.2.7, 3.5.4,

3

Amend District Rules to adopt wetland management rules based on wetland management classification

Part of watershed-wide effort

2007-2009

3.3.1, 3.3.2, 3.3.3, 3.4.1, 3.5.1, 3.5.4

MCWD Hydrodata Program

1

Monitor Minnehaha Creek

Part of watershed-wide hydrologic data program

Part of ongoing watershed-wide program

3.1.1, 3.1.2, 3.1.3, 3.1.4, 3.2.2, 3.2.3, 3.2.4, 3.5.1, 3.5.2

2

Monitor macroinvertebrates in Minnehaha Creek every five years

Part of watershed-wide hydrologic data program

2008, 2012

3.4.1, 3.4.3, 3.4.4

3

Identify base level flow in Minnehaha Creek

Part of watershed-wide study

Part of ongoing watershed-wide program

3.2.2, 3.2.3, 3.4.3, 3.4.4, 3.5.1, 3.5.2

4

Identify shallow wells to monitor groundwater levels

Part of watershed-wide study

2008

3.2.2, 3.2.3, 3.3.3, 3.3.2, 3.5.1, 3.5.2, 3.5.3, 3.5.4

MCWD Education/Communication Program

1

Provide targeted education materials to key stakeholder groups to meet objectives of plan

Part of watershed-wide education program

Part of ongoing watershed-wide program

All

2

Provide workshops, seminars, and brown bags for LGU staff, developers, and other interested parties

Part of watershed-wide education program

Part of ongoing watershed-wide program

3.1.1- 3.1.4, 3.2.1, 3.2.2, 3.2.4, 3.2.6, 3.2.7, 3.3.1, 3.3.2, 3.3.3, 3.4.1, 3.5.1 -3.5.4

3

Develop and distribute model ordinances and design standards that incorporate low impact design principles

Part of watershed-wide education program

Part of ongoing watershed-wide program

3.1.2-3.1.4, 3.2.2, 3.2.4, 3.3.1, 3.4.1, 3.5.1, 3.5.2, 3.5.4

4

Develop a small grant program to provide financial assistance to property owners desiring to implement BMPs on their property

Part of watershed-wide program

2008 and ongoing

3.1.2, 3.1.3, 3.1.4, 3.2.1, 3.2.2, 3.2.4, 3.3.1, 3.3.2, 3.3.3, 3.4.1, 3.4.3, 3.4.4, 3.5.1, 3.5.4

MCWD Operations and Maintenance

1

Inspect Minnehaha Creek erosion-prone areas at least annually

Part of watershed-wide program

Part of ongoing watershed-wide program

3.1.1, 3.1.4, 3.2.1, 3.2.2, 3.2.7, 3.4.4

2

Monitor high vegetative-diversity wetlands for exotic species

Part of watershed-wide program

Part of ongoing watershed-wide program

3.3.1

3

Inspect detention ponds to sustain removal efficiency

Incorporate into life-cycle cost of project

Part of ongoing watershed-wide program

3.1.1, 3.1.2, 3.1.3

Collaborative Projects

1

Work in partnership with MPRB to develop and implement lake aquatic management plans

Ongoing activity

Part of ongoing watershed-wide program

3.1.2, 3.4.2, 3.4.3, 3.4.5

2

Work in partnership with Creek riparian communities to improve riparian zone vegetation management

Ongoing activity

Part of ongoing watershed-wide program

3.1.1, 3.1.2, 3.1.4, 3.3.1, 3.3.2, 3.3.3, 3.4.1, 3.4.3, 3.4.4

3

Browndale Dam Scour Repair

$50,500

2008

Same

4

Work in partnership with Creek riparian communities and other agencies and utilities to repair streambank erosion and stabilize outfalls and other infrastructure: establish annual fund

$100,000 annually

2008 and ongoing

Same

5

Work in partnership with MPRB to investigate and implement potential capital improvements identified in the lake TMDLs

To be developed in the Lake TMDL Implementation Plan

As noted in the CIP

3.1.2, 3.1.3, 3.1.4, 3.2.2, 3.3.3, 3.4.1, 3.4.2, 3.4.5

6

Collaborate with the MPRB to evaluate feasibility of internal load controls on  Nokomis, Powderhorn, and Diamond Lakes

To be developed in the Lake TMDL Implementation Plan

Part of ongoing watershed-wide program

3.1.2, 3.4.2, 3.4.5