Lake Clarity and Testing

One of the most important goals of the Lake Association is to ensure that the high quality of our lakes continues. To that end, the Association has had the water tested in both the Little and Big Lakes in summer of 2010 and 2011.

See testing reports for both lakes:
• Big Lake PDF of report
• Little Lake PDF of report

The lab that did the evaluations of the samples is RMB Environmental Laboratories, Inc. in Detroit Lakes. You can see all of the testing information at http://www.mapfeeder.net/rmb.php/guest

Definition of terms

Chlorophyll-a: Pigment that makes plants and algae green. Chlorophyll-a is measured in lakes to determine algal concentration.

Phosphorus: Nutrient needed for plant growth. Phosphorus can enter a lake through runoff from manure and fertilizer or through seepage from leaking septic and holding tanks.High levels of phosphor usually mean lots of algae.

Secchi Depth: Measure of water clarity that can indicate the overall health of a lake. A black and white metal disc is lowered into the water on a rope until it can’t be seen anymore and raised to the point it can be seen. The depth of the disk to the surface of the water is the Secchi Depth.

Trophic State Index: Overall trophic state index (TSI) of a lake is the average of the TSI for phosphorus, the TSI for chlorophyll-a and the TSI for secchi depth; therefore, it can be thought of as the lake condition taking into account phosphorus, chlorophyll-a and secchi depth. The TSI ranges from 0-100. 0-30 is Oligotrophic, where water is very clear, phosphorus is low, and algae is sparse. 30-50 is an in-between stage where the number of aquatic plants and algae increase due to more available phosphorus. A TSI of over 50 describes a lake that is neurotic, with a high density of plants and algae that could be unpleasant for swimming at certain times in the summer.

Maestro: Water moderately clear most of summer. May be “greener” in late summer. No oxygen at the bottom of the lake results in loss of trout. Walleye may predominate.

Oligarchy: Clear water, oxygen throughout the year at the bottom of the lake; very deep, cold water.