On Jan. 22, the Minnesota Board of Water and Soil Resources approved $13.9 million in Clean Water Fund grants to improve water quality in lakes, streams, and groundwater aquifers across the state. The Comfort Lake-Forest Lake Watershed District was successful in securing two grants totaling more than $1.2 million for projects to improve water quality in Forest Lake, Comfort Lake, the Sunrise River and ultimately the St. Croix River. 

This first grant, worth $747,000, will treat 50% of the runoff flowing into the east basin of Forest Lake through Washington Judicial Ditch 6 using a multi-cell, iron-enhanced sand filtration treatment system. The project is expected to keep 85 pounds of phosphorus out of Forest Lake every year, which is the equivalent of removing more than 40,000 pounds of algae from the lake. 

Iron-enhanced sand filtration is a technology developed at University of Minnesota, St. Anthony Falls Laboratory in 2005 and is sometimes referred to as the Minnesota Filter. Iron-sand filters utilize a chemical process that causes phosphorus molecules to bind with iron in the sand as water passes through. The ability to pull “dissolved” phosphorus out of water makes iron-sand filters unique compared with other practices like stormwater ponds and sediment basins that can only catch phosphorus attached to sediment and organic waste. Iron-enhanced sand filters are also able to treat stormwater runoff in places with clay soil or high water tables where rain gardens don’t work.

The iron enhanced sand filter at WJD-6 will be the sixth built by the Comfort Lake-Forest Lake Watershed District. The first was constructed in 2013 through a partnership with CLFLWD and Washington County as part of a large stormwater treatment project north of Broadway Avenue, near Cedar Park. After construction, CLFLWD typically spends several years monitoring water quality downstream of these filters to ensure that they are functioning as designed. 

In 2020, Comfort Lake-Forest Lake Watershed District will also receive $492,000 to restore an existing ditched wetland complex that discharges directly into the Sunrise River, just north of Forest Lake. The project will increase flood storage capacity within 41.7 acres of district-owned, tax-forfeited property, and will keep 54 pounds per year of phosphorus out of the Sunrise River and Comfort Lake. Since the Sunrise River is one of the tributaries that carries the highest amount of nutrients to the St. Croix River, the project is expected to produce benefits downstream as well. (Editors note: In November 2019, the St. Croix River was officially deemed “impaired” by the Minnesota Pollution Control Agency due to its high phosphorous levels.)

Both the Forest Lake and the Sunrise River projects highlight the importance of using diagnostic monitoring to target cost-effective capital projects. Prior to developing these two projects, the Comfort Lake-Forest Lake Watershed District conducted water monitoring to measure the amount of phosphorus flowing into Forest Lake and Sunrise River from various tributaries. The CLFLWD then engaged EOR Inc. to conduct an engineering study that pinpointed the best locations for projects and most cost-effective practices to use. A similar diagnostic process was used for previous watershed district projects at Bixby Park and Shields Lake. 

The Minnesota Clean Water Fund was created by a voter-approved constitutional amendment in 2008. The Legacy Amendment allocates three-eighths of 1 percent of all sales tax revenue to projects that protect, enhance, and restore wetlands, prairies, forests, and fish, game, and wildlife habitat; preserve arts and cultural heritage; support parks and trails; and protect, enhance, and restore lakes, rivers, streams, and groundwater. Since 2008, the Legacy Amendment has generated $971.5 million for the Minnesota Clean Water Fund. 

More information about the Forest Lake or Sunrise River grant projects can be found at www.clflwd.org. 

Angie Hong is an educator for East Metro Water. Contact her at 651-330-8220, ext. 35, or angie.hong@mnwcd.org. 

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