SWCD Project Spotlight: Stormwater & Lee Lake

Lee Lake is a shallow lake in the city of Lakeville, about 20 acres in size, with an average depth of seven feet. In 2002, it was listed on the Minnesota Pollution Control Agency (MPCA)'s Impaired Waters List, due to poor water quality. However, because of continued work in the watershed, Lee Lake was recently de-listed, due to recently collected water-quality data showing decreasing phosphorus levels.

The small lake is valued both for its aesthetic appeal and the wildlife habitat (and viewing opportunities) it provides, and in recent years the city of Lakeville has worked with various partners to improve its water quality, with efforts ranging from organic carbon amendments to controlling invasive curlyleaf pondweed. Even with the recent improvements and de-listing, the city is interested in continuing to improve the small lake's water quality. 

Thus, this summer the area is the site of a major new stormwater project being undertaken by the City of Lakeville, with technical assistance and cost-share funding provided by Dakota County SWCD. Together, we're constructing a stormwater infiltration basin near the lake. Instead of going directly into the lake untreated, stormwater runoff will be diverted to the basin, where it can soak into the ground, be naturally treated by the soil, and recharge aquifers. A great deal of phosphorus, eroded soil, and other pollutants will never reach the lake, thanks to this new basin. 

“With the road construction, the timing is perfect to launch this project,” says Jayne Hager Dee, DCSWCD Board Supervisor for District 5, which includes Lakeville. “Lee Lake will soon be cleaner, clearer, fishable, and enhanced for recreation.” 

What's the deal with phosphorus? Phosphorus is a nutrient that is naturally found attached to soil particles, and also found in some fertilizers and other products. When it's washed into waterways, the boost of nutrients can cause explosions of algae in the water - one pound of phosphorus can lead to five hundred new pounds of algae. These algae blooms can look and smell bad, or even be toxic, and as they die and decompose, oxygen is removed from the water, leading to fish kills.   

SWCD Project Spotlight:
A Farmer's Waterways

Fixing erosion issues on a farmer's land is usually a win-win scenario: Reducing erosion means cleaner local streams and rivers, as sediments and nutrients are kept on the land, rather than running off into bodies of water where they can affect water clarity and cause drops in dissolved oxygen. The farmer benefits by retaining valuable soil and nutrients in the fields, where they're useful. Dakota SWCD works with landowner partners to design and install mutually beneficial conservation solutions.

This spring, we worked with a farmer in Marshan Township who was seeing erosion cutting through a few low paths in his fields. Crops planted in those areas of concentrated flow didn't survive, and valuable soil was washing away. This is a common issue in large fields, where water will inevitably concentrate in the lowest areas, and gradually erode them away.



Staff from Dakota SWCD worked with the landowner to design three grassed waterways on the property. The soil in these areas was re-graded, to concentrate the flow more evenly in these new swales, then covered in a hay-based mulch and planted with two kinds of seed: a fast-growing cover crop to come up right away, and the permanent grass that would come in more slowly, then come back each year.



The next step was to install straw wattles (also known as bio-logs, straw worms, straw noodles, and other fun names) across the grassed waterways, to act as a temporary measure to slow down water-flow in the event of a large rainfall, as the new plants were establishing themselves (they'll be removed later.) By the end of May, that first, fast-growing cover crop (a cereal grain) was coming up nice and green!



With time spent on maintenance these first couple years, the permanent crop will eventually fully establish itself, and the grassed waterway should function at a high level, reducing erosion and acting as a filter strip, for the next several years. 

Agricultural landowners interested in installing a conservation project on their own land should visit the Agricultural Resources section of our website, or call 651-480-7777. 
 

Quiz Yourself: Pollinators & Wildflowers

1. There are around ____ species of plants that are native to Minnesota.
   1. a) 500 species
   2. b) 1,000 species
   3. c) 2,500 species
2. Which of these flowers is found only in the state of Minnesota, nowhere else in the world? (See photos below.)
   1. a) Dwarf trout lily
   2. b) Showy lady's slipper
   3. c) Prairie blazing star 
3. Which of these types of animals are pollinators of native plants? Select all of the correct answers!
   1. a) Bees
   2. b) Butterflies
   3. c) Bats
   4. d) Black flies
   5. e) Black bears

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