Seasons The Greening of Maplewood
Cleaning Up Impaired Waters
By Virginia Gaynor, Natural Resources Coordinator If we could go back in time, to the 1940s, 50s, or 60s, armed with our current knowledge, we’d design our stormwater system differently. Back then the goal of engineers and urban planners was to quickly remove stormwater from neighborhoods to prevent flooding. The solution was to pipe it to nearby lakes, streams, and wetlands. For flood control – to protect people and property - we sacrificed water quality. The Federal Clean Water Act requires states to adopt water quality standards for surface waters. In Minnesota, the Minnesota Pollution Control Agency (MPCA) sets water quality standards and is responsible for maintaining a list of waters that do not meet standards. In Maplewood, the MPCA has designated two creeks and four of our nine lakes as impaired. Poor water quality is caused by pollutants. Stormwater runoff is piped into our lakes, streams, and wetlands, and with it comes nutrients, sediments, organic materials,
pathogens, metals, pesticides, trash, and debris. Mercury from atmospheric deposition settles in our lakes and is consumed by fish. Chloride (salt) from winter salting of roads makes its way into surface water and impacts aquatic species. And within a lake, sediments can release nutrients and degrade water quality. For Maplewood’s impaired waters, RamseyWashington Metro Watershed District (RWMWD) is responsible for preparing a Total Maximum Daily Load (TMDL) study to submit to the MPCA. This type of study identifies and quantifies the pollutants, determines how much pollutants need to be reduced to meet standards, and recommends strategies to achieve the reductions. From there it is up to the City, RWMWD, and partners to implement projects to reduce the specified pollutants and improve water quality (see article on page 2). Algae blooms and excessive vegetation in Maplewood lakes is a common complaint heard by City staff. Nutrients in stormwater runoff, especially phosphorus, act as fertilizers and drive algae and plant growth. Aquatic plants are a crucial part of the lake ecosystem, but algae and excessive vegetation can degrade the lake for aquatic
Fall 2017 life, recreation, and aesthetics. The MPCA updates the list of impaired waters every two years. Three Maplewood lakes that were on the 2014 list had improved enough to be delisted in 2016 including Keller Lake, Carver Lake, and Beaver Lake. The improvements in water quality can be attributed to stormwater management projects that have been implemented over the past several years. Most Maplewood residents are familiar with rain gardens – planted swales that capture stormwater and allow it to infiltrate. But the City, RWMWD, and developers have installed many other types of structures or systems to treat Maplewood stormwater: spent lime ponds, iron enhanced sand basins, grit chambers and sump structures, and large underground filtration systems. Strategies implemented within lakes are alum treatments, sediment removal, and carp control. RWMWD is testing the effectiveness of weed harvesting. And the City, businesses, and homeowners employ best management practices such as erosion control and sustainable lawn care to help reduce pollutants (see articles on page 3). If we all work together, we can clean up impaired waters.
Impaired Waters in Maplewood Lake/Creek Gervais Lake Kohlman Lake Wakefield Lake Lake Phalen Battle Creek Fish Creek 2016 MPCA List of Impaired Waters
Keller Lake, delisted as an impaired water in 2016
Impaired For Aquatic Consumption (mercury in fish) Aquatic Life, Recreation (chloride, nutrients) Recreation (nutrients) Aquatic Consumption (mercury in fish) Aquatic Life (chloride, poor biotic health) Recreation (E Coli)