Lake Minnetonka's 2013 Report Card Indicates Improving Water Quality

The water quality of most Lake Minnetonka bays ticked up a notch or remained static in the last year, according to data released today by the Minnehaha Creek Watershed District (MCWD), and graded as generally good or better in most areas. The report includes information collected by the MCWD, Three Rivers Park District and citizen monitors.

Fourteen of Lake Minnetonka's 31 bays and ponds received a grade of "B" or better, and seven bays improved their marks from a year ago (just one did so from 2010-2011). Additionally, seven bays and ponds with a grade of B+ or better retained their marks.

Because they are able to absorb higher levels of contaminants, bays with deeper water consistently receive higher grades that shallow areas.

Lake Minnetonka Bays and Ponds Receiving an 'A'

• Carmen (A-)
• Carsons
• Crystal (A-)
• Giddon
• Grays
• Lafayette
• Lower Lake North 
• Lower Lake South
• Marion
• Spring Park (A-)
• St. Albans
• Wayzata

Tanager Lake, Jennings Bay, Harrisons Bay, West Arm Bay, Stubbs Bay and Halstead Bay received the lowest marks, with all three being graded a "D."

Some of the poorer water quality sites used to have sewage treatment sites on them, a contributing factor to why the water quality isn’t as good, but conditions have improved during the last few years as residents and conservation groups have focused on their health.

Related Posts:

• Watershed District Grades Lake Minnetonka's Water Quality (2012)
• Water quality expert discusses Lake Minnetonka Water Quality (2011)
• Construction Underway on Innovative Stormwater Management Project

The Minnehaha Creek Watershed District takes water samples from May to September and bases its lake grades on three water quality parameters: water clarity (Secchi disk depth), algae growth (Chlorophyll-a ) and nutrients (total phosphorous). Factors such as aquatic plants, fisheries, harmful chemicals and over-use can also affect a bay's grade.

The Minnehaha Creek Watershed District’s lake grading method was developed in 1989. The grade shows how a lake or bay measures up compared to other area waters. Grades are an indicator of the perceived condition of the open water.

“The information we collect each year helps the District determine which water quality improvement projects to pursue,” said Eric Evenson, Minnehaha Creek Watershed District administrator. “The sound scientific data we have amassed provides a solid foundation for decision making.”

Evenson pointed to shoreline restoration projects that prevent erosion and filter runoff into Lake Minnetonka and an innovative sand/iron filter that removes dissolved phosphorous from a stream that feeds Dutch Lake as examples of recent water quality improvement projects the watershed district has implemented.

The Minnehaha Creek Watershed District also has a Cost Share Grant Program that helps fund the installation of rain gardens, pervious pavers, shoreline plantings and other storm water management techniques.

Pet waste, lawn clippings, fertilizer or other chemicals that reach Lake Minnetonka represent some of the biggest threats to local water quality. These and other contaminants typically enter the water via storm drains, going unfiltered into streams and tributaries.

The watershed district also offers the following recommendations to protect water quality:

• Residents can use rain barrels to control excess water flow into waterways, pick up pet waste, bag leaves and lawn clippings and reduce fertilizer use. 
• Boaters can protect lakes by observing the state law against transporting aquatic invasive species (AIS), including zebra mussels.
• Lakeshore property owners can help prevent the spread of AIS by only hiring certified lake service providers to install or remove water-related equipment (boats, docks, boat lifts or other structures). All hired providers that perform this work on Minnesota bodies of water are required by state law to undergo the training program. For more information, go to the AIS page on the Minnesota Department of Natural Resources website, www.dnr.state.mn.us/eco/invasives.

For more information on water quality of the district’s lakes and streams, visit the water quality section of Minnehaha Creek Watershed District’s website.