• Cottage Lake had fairly clear water with moderate nutrient concentrations and moderate algal growth.
• Cottage Lake has experienced considerable variation from year to year. Overall, total nitrogen and chlorophyll-a concentrations have been decreasing.
• Cottage Lake had a prolonged algal bloom with samples submitted for toxin testing in August through December. Toxin testing found elevated microcystin (in August and October) and anatoxin concentrations (in August) above the Washington State Recreational Guidelines.
This bathymetric map shows contour lines of equal depth, similar to a topographic map would for mountains and valleys. The red 'X' marks the location where water quality samples are taken.
This map shows the area of the watershed relative to the area of the lake. Generally speaking, the larger a watershed is relative to a lake, the greater the influence land use practices on lake water quality.
The average of these three TSI indicators during the growing season can be used
to place lakes in one of three broad categories:
<40 = oligotrophic (low productivity),
40 to 50 = mesotrophic (moderate productivity)
>50 = eutrophic (highly productive).
