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Vital Statistics

Watershed Area 450 acres
Lake surface area 21 acres
Maximum depth 40 feet
Mean depth feet
Public Park No
Boat Ramp Yes, no gas engines
Fish Present stocked rainbow


Volunteer monitoring began at Shady Lake in the 1980s and continued through 2004, when it was discontinued. Monitoring will be resumed in 2015. The data previously collected indicate this lake is low to moderate in primary productivity (threshold mesotrophic) with good water quality. Productivity may be decreasing slightly over time, the trend marked by moderate statistical significance. Profile data indicated that thermal stratification remains through summer, and during that time the sediments release a small amount of phosphorus into the deep water. Nitrogen to phosphorus ratios were above 20:1 through the summer, which generally favors other species of algae over bluegreens.

Shady Lake has a public access boat launch, and Eurasian milfoil has been identified in the lake, as well as a nuisance form of pondweed that may be a hybrid species. The community has undertaken local treatments to keep the weeds in check.

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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.

Click image to enlarge

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Water Quality Data  

Through a combination of efforts by volunteer lake monitors and King County staff, data relating to physical, chemical, and biological aspects of the lake have been collected for most lakes. The King County Lake Stewardship Program analyzes data to track long-term water quality trends in small lakes in western King County.

View or Download Data
Use this tool to view or download data from the lake in tabular format. You can define date ranges and select which parameters to view or download.

Chart Data
Use the charting tool to look at graphs showing single parameters for a single water year at a time.

Water quality over time
A common method of tracking water quality trends in lakes is by calculating the “trophic state index” (TSI) (Carlson, 1977) and testing the values for positive or negative trends over time. TSI indicators predict the biological productivity of the lake based on water clarity (Secchi) and concentrations of total phosphorus (TP) and chlorophyll a (Chlor). Generally at least 8 years of data without major lake management activities are needed to have confidence in a significant trend.

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).

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Reports and Related Links

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