Introduction

Wasserman Lake lies along a chain of lakes that forms the headwaters of Six Mile Creek which ultimately discharges into Lake Minnetonka.  Hydrology for Wasserman Lake is derived from a large sub-basin in addition to a large stream from the south.  Wasserman Lake is currently on the State list of Impaired Waters and a draft TMDL was developed for the lake in 2005.  The TMDL recommended a capital project to restore wetland area and streambank tributary to the south in order to reduce the external nutrient loading to Wasserman Lake. Sub-basins SMC-4 and SMC-5 are the areas where this proposed project would occur.  The 2007 MCWD Comprehensive Water Resources Management Plan has identified a capital project in this area to achieve an external nutrient loading reduction to the lake.  Existing land use in this area includes agricultural row cropping, grazing and single family residential, however the area in general is quickly developing.

The annual phosphorus concentration goal identified for Wasserman Lake is 50 mg/L.  In order to meet loading goals, MCWD will need to reduce loading to the lake by 749 lbs. of phosphorus per year.  The external load component of this reduction is 383 lbs. per year, with a goal of a 62 lb. reduction with the proposed Phase 1 project.  MCWD has identified a 53-acre property (shown below) within the subwatershed where a potential project could occur to achieve this goal.  The draft TMDL establishes the need to stabilize approximately 1500 feet of streambank and restore 30-acres of wetland on the site, however, this current effort seeks to develop a more detailed assessment of project alternatives and cost estimates to narrow the focus for final design (the current project).

The proposed project should investigate the feasibility, size, scope and location of restored wetland and streambank features that will assist in achieving the 62 lb. load reduction, enhance existing habitat features and improve the overall ecosystem function of Wasserman Lake and the southern tributary.  Development of the Wasserman Lake Wetland Restoration Project requires investigation of the following issues:

Restored Wetland/Streambank Siting

Identification of geographic areas and project site alternatives within the boundaries of the identified property that maximizes external load reduction and where hydrology provides for adequate surface and/or groundwater flows to maintain wetland conditions in existing or altered topography, hydrology or stream hydraulics.  Adequate technical analysis of runoff rate, path, timing of inflow/outflow, duration and frequency of ponding and saturation, and shear stress of existing and proposed conditions is required.  Wetland restoration site(s) could either build/expand upon existing wetlands or be created in locations on site where conditions permit. Proximity to important natural resources within the subwatershed must be considered and high quality upland natural areas must not be negatively affected as a result of restoration of wetland features. 

Wetland Type

Wetland Type and Classification must be integrated into the other important natural resources planning throughout the site.  Considerations of vegetation species and wetland function must be evaluated in order to optimize the value of existing wetlands on site as well as the restored features.  Proposed restored wetlands on site should be representative of natural or historic wetland features within the area and should complement the vegetation types of high quality upland features on the site. Wetland vegetation must be selected relative to the hydrologic considerations cited above in analysis of wetland siting.  Analysis must also be included which dictates the method for implementing the project.

Upland Resources

Wetland buffers adjacent to restoration areas should be free and clear of exotic and invasive species and generally consistent with other natural features on the site.  Evaluation of existing and proposed site conditions must take into account the establishment and maintenance of buffer areas as well as restoration areas.

Feasibility Study Report

Further questions and concerns can be addressed by contacting MCWD Planner Michael Wyatt at (952)471-0590 ext. 204 or mwyatt@minnehahacreek.org.