Background

The headwaters of Long Lake Creek is the discharge from a concrete weir at the outlet from Long Lake in the city of Long Lake. From there it flows approximately 2.7 miles through wetland and forested areas of Orono to its mouth at Tanager Lake, which discharges to Browns Bay on Lake Minnetonka.

Water quality is monitored at two locations in the creek, as well as in downstream Tanager Lake (see map below). Phosphorus levels are generally greater at the downstream site, suggesting that the watershed or adjacent wetlands are contributing to phosphorus loads in the creek and downstream Tanager Lake. Tanager Lake has been placed on the State Impaired Waters List because of its high nutrient concentrations. The 2007 Minnehaha Creek Watershed District (MCWD) Comprehensive Plan identifies an interim in-lake phosphorus concentration goal of 70 μg/L for downstream Tanager Lake. The state standard and long-term goal for the lake is 40 μg/L. To meet the interim phosphorus concentration goal, phosphorus loading to Tanager will need to be decreased by 923 lbs. of phosphorus per year.

Projects identified in the 2007 MCWD Comprehensive Plan to improve water quality in Long Lake Creek and Tanager Lake include:

• Wetland Restoration Projects (2008/2010)
• Long Lake Stream Restoration Reach 5 (2012)
• Regional Pond at LLC-51 (2013)
• Regional Pond at LLC-48 (2016)

Feasibility

To identify and prioritize the most effective projects for improving water quality in this subwatershed, MCWD combined the feasibility work for these capital projects into one comprehensive Long Lake Creek Corridor Improvements feasibility study. The feasibility work includes investigation of the following issues:

1. Assessment of loading throughout the subwatershed (external, internal, sewage lagoon, SSTS)
2. Assessment of dump site and sewage lagoon
3. Identification of streambank restoration/stabilization opportunities
4. Identification of stream re-meander opportunities
5. Identification of wetland restoration opportunities
6. Identification of ponding opportunities (LLC-51 and LLC-48)
7. Assessment of internal loading in Tanager Lake

This feasibility study was completed in 2011 (see report below), and it identified and prioritized a list of potential projects. From that list, 4 projects were selected and ordered for further investigation and design in 2012 (see map below). These include:

1. Streambank stabilization downstream of the Brown Rd outfall
2. Streambank stabilization downstream of the Wayzata Blvd outfall
3. Restoration of wetland D-117-23-03-016
4. Stream remeander in Reach 2

These projects are scheduled for design in 2012 and construction in 2013-2014. In addition, the MCWD is working with the Met Council Environmental Services to develop concepts for the restoration of the former Long Lake Sewage Lagoon.