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Bass and Pomerleau Lakes Alum Treatment Project

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Project Update
The Bass and Pomerleau Lakes Alum Treatment Project was reviewed and approved by the Plymouth City Council at their April 23rd, 2019 meeting.

View the Alum Treatment Project Plans. Below is an expected timeline of the project areas:

Sunday, May 12: Arrive at Pomerleau late afternoon/early evening
Monday, May 13: Begin Pomerleau application at 11:00 AM
Tuesday, May 14: Complete Pomerleau application at 12:00 PM
Tuesday, May 14: Arrive at Bass late afternoon
Wednesday, May 15: Begin Bass application at 7:00 AM
Wednesday, May 15: Complete Bass application by early evening
Thursday, May 16: Demobilize equipment from Bass by 12:00 PM

Project Overview
The City of Plymouth and the Shingle Creek Watershed Management Commission (SCWMC) are working to improve the water quality in Bass and Pomerleau Lakes to help the lakes meet water quality standards as outlined by the Minnesota Pollution Control Agency (MPCA). In 2002 the MPCA listed Schmidt, Bass and Pomerleau Lakes as impaired waters for excess nutrients. In 2009, the SCWMC Engineer completed a Total Maximum Daily Load (TMDL) and Implementation Plan for all three lakes to assess and to provide strategies for reducing the nutrient loading within the watershed.

The SCWMC completed a TMDL 5 Year Review in 2017, which summarized the progress towards meeting the goals to date and updated the nutrient targets for improving Schmidt, Bass and Pomerleau Lakes by utilizing more recent and complete water quality monitoring data. The review indicated that the watershed phosphorus loading into the lakes has been significantly reduced as a result of projects completed within the watershed by the City of Plymouth, residents and lake associations and indicated that internal phosphorus loading management in Bass and Pomerleau Lake would be appropriate at this time.

Proposed Bass Lake Alum Treatment Area
            Bass Lake Treatment Area (PDF)

Proposed Pomerleau Lake Alum Treatment Area
            Pomerleau Lake Treatment Area (PDF)

The proposed internal management solution for Bass and Pomerleau Lake is to apply aluminum sulfate (alum) treatments on Bass and Pomerleau Lakes in the spring of 2019 and again in the fall of 2019 or the spring of 2020 to reduce the internal phosphorus loading and improve water clarity in both lakes.

The City of Plymouth, the Shingle Creek Watershed Management Commission and The Bass Lake Improvement Clean Water Land and Legacy logoAssociation will be working with the Minnesota Department of Natural Resources to develop a Lake-Wide Aquatic Vegetation Management Plan that will manage invasive aquatic vegetation in the lake.

The Shingle Creek Watershed Management Commission has received grant funding for this project from the Minnesota Board of Water and Soil Resources through the Clean Water,
Land and Legacy Amendment.

Additional Information


Ben Scharenbroich, Senior Engineering Technician
Plymouth City Hall | 3400 Plymouth Blvd. | Plymouth, MN 55447-1485
P 763-509-5527 |

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