Water testing results show decline in water quality of some area lakes
The Whitefish Area Property Owners Association (WAPOA) recently completed another year of water sampling on area lakes.
WAPOA is currently sampling 38 area lakes and an additional six inlets and outlets. Due in large part to a substantial number of individual volunteers, lake samples are taken in each lake once each month, May through September.
The tests include a Secchi disk reading for water clarity, chlorophyll reading (algae) and a phosphorus reading (nutrients).
The Secchi disk, created in 1865 by Pietro Angelo Secchi SJ, is a circular disk used to measure water transparency in oceans and lakes. The disc is mounted on a pole or line, and lowered slowly down in the water. The depth at which the pattern on the disk is no longer visible is taken as a measure of the transparency of the water. This measure is known as the Secchi depth and is related to water turbidity.
Together, Secchi, chlorophyll and phosphorus data give a TSI value (Trophic State Index); in other words, the overall health of the lake. The TSI values provide a way to monitor lakes and provide direction in how to best maintain or improve lakes and lands, including land use practices, protecting sensitive shorelines, implementing shoreline restoration, and addressing aquatic invasive species issues.
The water quality of lakes has been declining over the years. Specific examples of recently increasing TSI values on local lakes are shown in the chart.
Although these may appear to be small changes, the trend is reason enough for concern. And, it is important to note that a 1-point increase in TSI indicates a 10 percent increase in algae.
Five good reasons to work at lowering the TSI values on the lakes are clearer water, less algae, beaches are less clogged with plants and more desirable for swimming, providing more oxygen in the water, and game fish prefer waters with a lower TSI. Rough fish prefer water with a higher TSI.
WAPOA encourages all lakeshore property owners and those who use the lakes to take action to reduce the TSI values by reducing water runoff, especially preventing water from fertilized yards and fields to flow into the lakes and streams; avoiding use of phosphorus-based fertilizers; avoiding over-development of property near lakes and streams; and properly disposing of chemical waste.
A complete and detailed TSI Map for 2013 can be found at WAPOA’s website at www.wapoa.org, then click on “Lakes Water Quality.”