LAKE SARAH AND LAKE INDEPENDENCE STORMWATER RETROFIT ANALYSIS - MAY 2014
The City of Independence contracted Hennepin Conservation District and Anoka Conservation District to complete a stormwater retrofit analysis for the purpose of identifying and ranking water quality improvement projects in those portions of the City of independence that flow into Lake Sarah and Lake Independence. Both lakes have completed Total Maximum Daily Loads (TMDL) and TMDL implementation plans for impairment by phosphorus. The City of Independence has annual phosphorus reduction goals of 143lbs for Lake Sarah and 535 lbs for Lake Independence. These reductions are likely to be met only with an aggressive pursuit of structural and cultural practices.
This analysis was primarily intended to identify projects in the City of Independence to improve water quality in Lake Sarah and Lake Independence to achieve phosphorus waste load reduction goals identified in local water plans and TMDL implementation plans. Some projects were identified that fall outside of the City of Independence boundaries and are included in this analysis because of their close proximity to the lakes or their likely impact on project selection by the City of Independence.
The federal Clean Water Act requires states to adopt water quality standards to protect the nation’s waters. These standards define how much of a pollutant can be in a surface and/or ground water while still allowing it to meet its designated uses, such as for drinking water, fishing, swimming, irrigation or industrial purposes. Many of Minnesota’s water resources cannot currently meet their designated uses because of pollution problems from a combination of point and nonpoint sources.
Impaired Waters and Total Maximum Daily Loads (TMDL)
For each pollutant that causes a water body to fail to meet state water quality standards, the federal Clean Water Act requires the MPCA to conduct a TMDL study. A TMDL study identifies both point and nonpoint sources of each pollutant that fails to meet water quality standards. Water quality sampling and computer modeling determine how much each pollutant source must reduce its contribution to assure the water quality standard is met. Rivers and streams may have several TMDLs, each one determining the limit for a different pollutant. The List of Impaired Waters can be accessed via links on the MPCA website, Impaired Waters page.