• In 2024, the chlorophyll and total phosphorus TSI values were in the eutrophic range while the Secchi TSI value was in the mesotrophic range. Eutrophic lakes (TSI >50) have less-clear water with high nutrient concentrations and high algal growth. Eutrophic lakes are also more likely to have frequent algal blooms.
• Echo Lake’s high nutrient concentrations and nitrogen-to-phosphorus (N:P) ratios below 25 both indicate that Echo Lake is likely to have algal blooms dominated by cyanobacteria (which have the ability to produce toxins).
• Numerous algal bloom samples were collected for toxin testing in 2024. In August through October, toxin testing found elevated microcystin concentrations above the Washington State Recreational Guideline of 8 µg/L.
• Investigate potential sources of phosphorus that could be contributing to increasing phosphorus trend.
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).
