The Online Lower Minnesota River Watershed District News, June 2004

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Executive Summary of the Bonestroo study (click to see)

Executive Summary map showing the exact locations of the prioritized projects (click for enlarged view) 







engineering firm fine-tunes district’s water-management plan

This May, Bonestroo Rosene Anderlik & Associates, a St. Paul engineering and architecture firm, finished a study begun last fall that surveyed water-management data and the desires of various cities, counties, agencies, and individuals in the District. The aim of the study, conducted by phone and email, was to integrate the data about how water resources are being managed; to analyze these data; and, on that basis, to help the District prioritize the projects that need immediate attention.

Identified in the study’s “Implementation Guidance Table,” these high-profile projects were already high on the list in the District’s second-generation 1999 water management plan. However, as Bonestroo engineer and project manager Dan Edgerton reports, the firm’s study “helped supply direction and suggest specific actions. We also helped the District identify costs and potential partners for the projects.”

High-profile projects

What water bodies need attention and why? The District’s 5-year-old plan identified these top-priority sites:

  • Chaska’s clay hole lakes (Courthouse, Firemen’s, and Clay Hole)

  • Assumption Creek

  • Dean Lake

  • Minnesota River

  • Nicols Fen

  • Harnack and Kennealy creeks

The clay hole lakes are a compelling example of why water bodies need protection. According to Edgerton, it’s important that the District help the city of Chaska preserve the lakes’ water quality. Firemen’s Lake, for one, is used for swimming, and if it’s allowed to degrade as the surrounding area develops it could end up being like many degraded city lakes, says Edgerton. “You don’t want swimmer’s itch or algae blooms. You won’t want to swim there if the water’s really murky. If lakes receive a lot of stormwater that’s not treated very well, that’s what you’ll get. And degraded lakes are very expensive to fix. It’s much less expensive in the long run to protect good-quality lakes and streams than to fix degraded ones. You want to try to build in controls as the area develops to make sure proper ponding, or infiltration, or other water-quality treatment practices will prevent nutrients and other pollutants from getting into the water body in the first place.”

So, the District may spend $20,000 to $35,000 to work with the city of Chaska and Carver County to develop a management plan for protecting and even improving the water quality of the lakes. 

In the case of Assumption Creek, the District may invest $20,000 to $40,000 to help potential partners like Chanhassen, Chaska, and the Minnesota DNR to develop effective management guidance for the stream and its watershed. The plan could help establish the viability of the creek as a trout habitat, which requires cold water; recommend monitoring; and alert citizens to impacts of further development, whether roads or building. 

Mitigation strategies

Edgerton mentions a “mitigation strategy” for Assumption Creek that would help offset these developmental impacts. “Ideally, if we do some improvements now, put some controls on land use, we can help restore the creek to the cold, clear trout stream it may have been at the start. For example, we can limit the volume of surface run-off to the waterbody, because surface runoff is warm when it comes off parking lots, for example, and heats up. Trout are very sensitive to rises in temperature, and when water gets to a certain level they stop reproducing and, at a higher level still, they die.” One mitigation strategy is to develop what are called “rainwater gardens, low areas planted with water-tolerant plants. We try to direct water to such low-lying infiltration areas and hold it there, so that it can seep into the ground and move toward the creek as clean and naturally cooled ground water.” The District would partner with the cities of Chaska and Chanhassen, as well as other interested stakeholders, to enact such mitigation efforts.

As the study proceeded, Bonestroo learned not only about participants’ past involvement in water-improvement projects but their interest in future efforts too. Chaska expressed clear interest in protecting its lakes. Burnsville was concerned about riverbank erosion that could threaten roadways. And various stakeholders, Edgerton indicates, “were looking for leadership from the District so they might do something to restore the eroded ditch next to Nichols Fen and prevent the fen from drying up and losing rare species. So the District would help harness and coordinate the energies of various players, including Eagan and the Minnesota DNR.” 

What about the Minnesota River?

Of course, the Minnesota River remains the defining waterbody in the District. And the Bonestroo study, after the 1999 District plan, puts appropriate emphasis on this resource. With the installation of a new gaging device at the mouth of the river at Fort Snelling, the District is already funding efforts to determine water quality in the Minnesota and Mississippi rivers, and what might be done to improve it.

More details of the study

  • The entire study is available here

  • The executive summary can be found here, including Implementation Guidance Table and, at the end, a detailed map showing where each project is located in the District