What is the problem?
What is the solution?
Lake Independence was added to the Minnesota impaired water list in 2002 due to an excess of phosphorus (more information on the water page under Info). LICA, Three Rivers Park, Hennepin County Environmental Services, the DNR and many other patrons of the lake have been working since then to reduce the amount of phosphorus in the lake to improve water quality.
Baker Ravine Stabilization will
substantially reduce phosphorus loading
Reduce the amount of phosporus, entering the lake from all sources in order to reduce the growth of algae bloom (that is where the TMDL-Total Maximum Daily Load-comes in, it's to total ammount of phosphorous that can enter the lake per day without overfilling) and other aquatic invasive species.
After all sources of phosphorous loading have been controlled, the lake can begin to heal and a whole lake alum treatment to boost clarity can be considered.
Kim and I are volunteer lake quality monitors for the MN Pollution Control Agency (MPCA) Citizens Lake Monitoring Program. We collect water quality data using a Secchi disk - an 8-inch circular black and white plate attached to a calibrated rope. The disk is slowly lowered into the lake and a reading is taken at the point the white disk is no longer visible. Then the disk is lowered further and slowly raised, noting the reading when the disk re-appears. We submit the readings to the MPCA at the end of each monitoring season.
The Secchi disk measures transparency, which is an excellent indicator of water quality. Water transparency indicates the amount of light penetration and indirectly shows the amount of suspended material in the water, which may include sediment and plant nutrients such as algae. Plant nutrient sources include septic tanks and lawn and farm fertilizer. Sources of sediment include shore erosion, farm fields and storm runoff. By measuring Secchi depth throughout the season and from year-to-year, transparency trends (and by extension water quality trends) can be observed.Over time, the collected data helps detect water degradation.
The ravine that runs through Baker Campground is severely eroded and has been identified as a major source of phosphorus loading, contributing an estimated 277 lbs. of phosphorus and 300 tons of sediment annually. Ravine improvement was identified as a high-priority project. A plan was developed for stabilizing the ravine with rounded field stone and angular rip-rap. Stabilization will produce an estimated reduction in phosphorus loading of 134 lbs per year.
The project will cost $520,000. Grants from the state Clean Water Legacy Fund and Hennepin County will cover a major portion of the cost. Additional funding will be provided by the Pioneer-Sarah Creek Watershed Commission, the City of Medina, City of Independence, Three Rivers Parks and a $2,500 contribution from LICA. Project planning has been completed but construction is delayed until November, 2019 due to the Army Corps of Engineers permitting process.
This project is another example of multiple stakeholder groups working together to achieve a common goal: To improve the water quality of Lake Independence.
In 2007, the EPA approved the TMDL (Total Maximum Daily Load) Reduction Plan for Lake Independence. The plan requires a reduction in phosphorus loading of 1,081 lbs. per year. Responsibility for meeting this goal is shared among the City of Independence, the City of Medina (including Three River Parks) and the City of Loretto.
Secchi Depth Measurements on Lake Independence
by LICA members Jim and Kim Klancke
What an excess of algae can do...
New York Times article
This graph combines data from Secchi measurements taken on Lake Independence during spring and summer from May, 2013 to October, 2018. The data are plotted as 10-day moving average measurements to smooth the data to better see the trend in water clarity throughout the spring and summer collectively, as individual readings have some variability based on a number of factors such as sunlight, waves, recent rainfall, etc. For example, the data point on Day 32 is the average of readings from 2013-2018 in the 10 day period surrounding June 1. Typically, water quality gradually decreases beginning in June, stabilizing around the 4th of July and holding through August.
Because the water quality fluctuates throughout the spring and summer, taking an average of one year’s measurements is not particularly useful. Trends only emerge when data is collected and compared over a number of years. To date, the MPCA is reporting no detectable trend in water quality. The summary for Lake Independence can be found on the MPCA website.