At Three Rivers’ Baker Park, ravine stabilization is designed to improve Lake Independence’s water quality

Pioneer-Sarah Creek Water Management Commission taps $416,000 in Clean Water Funds from BWSR plus $59,500 Hennepin County grant

Landscape architect Seth Bossart, left, of Wenck Associates, discussed the Baker Park Reserve ravine stabilization project with project foreman Nate Bauerly of Minnesota Native Landscapes on Dec. 19, 2019. At bottom left is one of the rock grade-control structures installed in the main channel and two tributaries. The project used 2,890 tons of rock, 1,850 square yards of straw erosion-control fabric, 2,180 square yards of straw and about 20 pounds of native seed including nine grass species and seven forb species. The banks were graded, and then the seed was cast and covered with a blanket. The project will reduce phosphorus loading to Lake Independence by about 134 pounds a year. Photo Credit: Ann Wessel, BWSR

A project finishing up this spring in Three Rivers Park District’s Baker Park Reserve is designed to improve the water quality of Lake Independence. One of Hennepin County’s most heavily used lakes, it is impaired for excessive nutrients.

A 2014 subwatershed analysis identified channel erosion in a ravine leading to the lake as a top sediment and phosphorus contributor. It carried an estimated 277 pounds of phosphorus and 300 tons of sediment — the equivalent of 23 dump truck loads — to Lake Independence annually. Phosphorus feeds the algae that can turn lakes green.

“The lake has always had severe algal blooms,” said Brian Vlach, senior water resources manager for Three Rivers Park District. “The lake is pea-green through portions of the summer due to algal blooms.”

Brian Vlach, Three Rivers Park District’s senior water resources manager, monitored progress of the Baker Park Reserve ravine stabilization project. The park district is among the project partners. Its involvement has included collecting water quality information in the park. Photo Credit: Ann Wessel, BWSR

The $520,000 Pioneer-Sarah Creek Watershed Management Commission ravine stabilization, which came in $34,000 under budget, will accomplish an estimated 15% of the phosphorus reduction needed to meet Minnesota Pollution Control Agency water-quality standards.

Despite the algae, 832-acre Lake Independence remains a primary attraction in the metro park that saw well over a half-million visitors in 2018. The WMC deemed Lake Independence a high-priority sentinel lake, based partly on its high visibility and recreational use.

The stabilization is a first step to reduce external phosphorus loading. To accomplish its long-term goal of increasing the lake’s clarity to 8 to 12 feet, the WMC is considering a future alum treatment to address internal phosphorus loading.

Three Rivers’ 2007 TMDL (Total Maximum Daily Load) study led to the Lake Sarah and Lake Independence Stormwater Retrofit Analysis Study that identified the Baker Park Reserve project in 2014. Lake Independence draws crowds to its swimming beach within the park. Photo Credit: Three Rivers Park District.

Lake Independence attracted more than 27,100 swimmers to the park’s two beaches, launched nearly 15,600 boaters from its public access and drew more than 3,400 anglers to its shore in 2018, the most recent year for which Metropolitan Council data are available.

“It has been a very good fishing lake,” Vlach said. A community of fish houses pops up during the winter. Anglers target crappies in early spring, walleye in the summer, and muskies well into the fall.

“It’s been a good muskie fishery in the past. There’s some big muskies in there. A lot of people have had success,” Vlach said.

A technical adviser to the WMC, Three Rivers coordinated the project. Minnesota Native Landscapes of Otsego was the contractor. Wenck Associates of Maple Plain handled project design and construction administration.

Work was made possible by a $416,000 Clean Water Fund grant from the Minnesota Board of Water and Soil Resources. A $59,500 Hennepin County Opportunity Grant from the county’s Environment and Energy Department, plus $44,500 cost-share among the WMC, park district, Lake Independence Citizens Association and the cities of Independence and Medina covered the balance.

“Clean Water Funds by all means enable a project like this,” Baker said “The cities of Independence, Medina and a small part of Maple Plain as the cities of benefit just really would not have the funds for that. We’ve had great support from BWSR as well as Hennepin County and Three Rivers Park District to ultimately pull the funding together.”

Construction finished in mid-February.

Touch-up seeding is planned in a few spots, and the park district will plant shrubs to discourage people from entering the ravine. But little evidence of construction remained this spring, as native wildflowers and grasses emerged from erosion control blankets covering the dirt-topped structures and re-sloped banks.

A drone offers another view of the ravine stabilization in Baker Park Reserve, which is designed to improve the water quality of Lake Independence. Seven species of wildflowers and nine grasses were planted in the dirt covering rock riprap and topped by an erosion control blanket. The rock cross-vanes serve as erosion control structures. Photo Credit: Wenck Associates

Native plants — seven species of wildflowers and nine grasses — were planted in the dirt covering rock riprap and topped by an erosion control blanket. In mid-December, the Minnesota Native Landscapes crew was installing riprap and re-sloping the ravine’s banks, moving downstream toward the lake. Newly constructed rock cross-vanes, which serve as grade-control structures, stood out against the snow.

The project was designed so park visitors won’t see a trace of construction.

Originally slated for the previous winter, the 2,200-foot channel stabilization was delayed in order to obtain a U.S. Army Corps of Engineers permit, required because of the project’s scope. Vlach said the delay resulted in more lead time and therefore lower bids.

Devan Maruska of Minnesota Native Landscapes staked an erosion control blanket Dec. 19, 2019, in Hennepin County’s Baker Park Reserve. Pioneer-Sarah Creek Watershed Management Commission drew from a Clean Water Fund grant to stabilize the ravine, which was identified as a significant source of phosphorus entering nutrient-impaired Lake Independence. The erosion control blanket covered a layer of dirt and rock. Photo Credit: Ann Wessel, BWSR

Pending BWSR approval, the projected surplus could be used to fund smaller projects within the 7,632-acre watershed. Those might include native plantings in Baker Park rain gardens, Lake Independence shoreline restorations, a carp barrier on the Ardmore Channel or erosion control projects elsewhere in the watershed.

The grant expires in December 2020.

The Hennepin County Environment and Energy Department is developing other cost-share and locally funded projects within the watershed. Department staff provide technical assistance and support to Pioneer-Sarah Creek WMC, operate a grant program, and conduct landowner outreach.

This season, staff is developing a project to stabilize and curb ice-related erosion affecting 65 feet of a 400-foot Lake Independence shoreline property. Two more projects affecting Lake Independence could be installed next year.

Conversations with landowners about potential conservation projects continue.

Bluestem grass was used in the erosion control blanket. After a Dec. 19, 2019, construction meeting, a group from Wenck Associates, Minnesota Native Landscapes, the Pioneer-Sarah Creek Watershed Management Commission, the park district and BWSR toured the site. Photo Credit: Ann Wessel, BWSR

Nearly 500 private landowners’ properties drain directly to Lake Independence or to Lake Ardmore, which are connected by a channel. About half are lakeshore or suburban; half are rural residential or agricultural.

“The two staff added thanks to capacity funds have been the first boots-on-the-ground landowner assistance staff that (Hennepin County) has had in many years,” Galles said of the rural conservationists hired within the past three years.

Three Rivers’ continued water-quality monitoring and a re-evaluation of the TMDL will help to determine where in the watershed to focus next.

The Minnesota Board of Water and Soil Resources’ mission is to improve and protect Minnesota’s water and soil resources by working in partnership with local organizations and private landowners. www.bwsr.state.mn.us

--

--

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Minnesota Board of Water and Soil Resources

Our mission is to improve and protect Minnesota’s water and soil resources by working in partnership with local organizations and private landowners.