Agenda - Council - 08/06/2018 - Laserfiche WebLink

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Surface Water Hennepin County's water resources, which include lakes, streams, groundwater, and wetlands, are an important component to our quality of life and the overall health of our environment. Hennepin County has 200 lakes, 640 miles of streams, and more than 45,000 acres of wetlands. Protecting our water resources is not only important to human health, it is also vital to preserving wildlife habitat and providing economic and recreational value. Many water pollutants come from human activities on the land. During the last few decades, state and federal regulations have limited point source discharges of waste water and sewage pipes into our waterways. Today the majority of our water pollution comes from nonpoint sources, which includes runoff from yards, roads, farms, and farm tiles. Prairie near Hennepin County Public Works Facility in Medina As more county land is developed, there is an increase in impervious surfaces (see map W-2) and a reduction in vegetated surfaces that capture runoff and filter water. When it rains or snows, much of the stormwater that falls on these hard surfaces runs off instead of soaking into the soil. As it travels, stormwater picks up pollutants like sediments, fertilizers, grass clippings, pet droppings, oil, and pesticides and delivers them directly into storm sewers. Eventually, some of this water ends up in lakes, streams, or rivers without filtration or treatment (see map W-3 to visualize water flow throughout Hennepin County). All water in Hennepin County flows to the Crow River, Mississippi River, or Minnesota River and contributes to the water quantity and quality. By properly managing yards, roads, and farms, all residents play an important role in preventing pollution of water resources. Emerging issues Hennepin County's water resources are a critical and valuable asset to all residents. To sustain and improve them for years to come, it is necessary to understand the future issues that may arise and threaten lakes, rivers, wetlands, and underground infrastructure. The impacts of climate change will put more stress on natural resources. Temperature and moisture patterns will change faster than plant and animal communities can adapt, resulting in changes to ecosystems, habitat loss, and spread of invasive species. Climate change can stress plants and animals, making them more vulnerable to disease and less competitive with invasive species. Additionally, an increased frequency of both flooding and droughts will put additional pressure on our stormwater management infrastructure and groundwater resources. Land use is projected to shift in the county through 2030 with more land being developed and less land being open space or agricultural. Development is accompanied by additional stormwater infrastructure that often speeds water off the landscape, through systems of pipes, and to nearby water bodies much more quickly than water would move naturally through lakes, rivers, and streams. The increased rate at which water reaches streams and rivers contributes to bank and stream channel erosion, a significant water quality concern for Hennepin County and downstream communities. Identifying strategies for both mitigating and communicating about this emerging water quality concern — one that is not a pollutant but a human - made alteration in hydrology — is one of the most challenging issues facing water resource managers today 5