Lakes Water Quality



1. Water quality map Whitefish area using “TSI.”  MAP CLICK HERE

Understanding the TSI water quality measurement

-As the TSI number goes up, the water quality is considered to be lower.

-Lower quality water has low clarity, is green rather than crystal clear, may smell

-Lower quality water has more algae, supports rough fish, has less oxygen

The Whitefish Area Property Owners Association (WAPOA) regularly samples and tests water on over 35 area lakes.

a.  How clear is the water?  A simple but powerful test: lower a white metal Secchi disk into the water until it disappears. Deeper is better.

b.  How much algae is in the water?  Algae contain a green pigment which can be measured by placing the water sample under a special light.

c.  How much phosphorus is in the water? Chemical tests of the water measure this.

The three measurements above (white Secchi disc, chlorophyll-a, and phosphorus) are averaged to get the TSI (trophic state index).   The higher the TSI, the worse the water is.


2. Water quality on the Whitefish Chain using only “Water Visibility” (Secchi disk)  Click Here Only the water visibility is measured in the above test

3. Water quality Off-Whitefish Chain using only “Water Visibility” (Secchi disk) Click Here Only the water visibility is measured in the above test.

Explanation of the “Water Visibility” graphs  (#2 and #3)

If the “trendline” goes up as it crosses the map from left to right, then the water visibility is getting worse.

This is a PDF file, so you can click on the up and down arrows to move to the various lakes. In between lakes is the data from which the maps were made.

Note: Some lakes do not have enough years of sampling to draw a chart that show whether the trend is toward better or worse. For those lakes just the actual data is shown.


EXPERT SECTION:  Phosphorus Load Studies   Scroll to bottom of this page to access three very technical phosphorus load studies. Approximately 75 pages.     NRCS HUC 07010105

Phosphorus Load Studies

Why is the study of the amount and source of phosphorus in water important?

1. Certain microscopic floating plants found in lake water are called algae.

2. In lakes in our area the mineral phosphorus is the limiting element. That means the amount of algae present depends on the amount of phosphorus present.  If there is a lot of phosphorus then there is a lot of algal growth.

3. Too much phosphorus promotes too much algal growth leading to smelly, undesirable lake water. The water becomes cloudy.The water becomes unfit for recreation.  Some forms of algae are even poisonous to animals drinking the water.  The concentration of algae can be so high that sunlight cannot get to beneficial plants that ordinarily grow in water. The plants die. Then the algae may die. This uses up oxgen which fish need. Fish die.

4. Phosphorus is found naturally in some soils and may wash into water. Phosphorus also comes from lawns and gardens, fertilizers, farm animals, human waste, septic tanks, sewage treatment plants, and detergents.

WAPOA has extensively investigated the amount and source of phosphorus in the Whitefish area.

To be statistically accurate many water samples have to be taken recurrently in many places over many years.

Here are 3 studies led by Jack Wallschlaeger of WAPOA:

Whitefish Area Phosphorus Loading 2001  NRCS HUC 07010105 0.9MB PDF  Click Here

Pine River Phosphorus Export 2003  1.27 MB PDF NRCS 07010105 HUC Click Here

Bungo Creek Phosphorus Export 2005  1.37MB PDF NRCS HUC 07010105 Click Here