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Vital Statistics

Watershed Area 469 acres
Lake surface area 88 acres
Maximum depth 39 feet
Mean depth 20 feet
Public Park Yes
Boat Ramp Yes, no gas engines
Fish Present Bass, stocked rainbow


Volunteers monitored Pine Lake from the 1980s through 2014. This lake in Sammamish is clear, lightly buffered against pH change, and currently low in primary productivity (oligotrophic) with very good water quality. Productivity has remained steady since 1998, and nutrients show no strong trends. Diversion of a small inlet occurred in 1988 to address high nutrient inputs. The lake has a Lake Management Plan completed by the city. Thermal stratification is stable in summer, but sediments release very little phosphorus to deep water, while minor ammonia increases indicate oxygen remains present. Nitrogen to phosphorus ratios in the upper water are above 25:1 during the summer, which does not favor cyanobacteria. Few reports of toxicity have occurred, and levels have been low. Red swamp crayfish have invaded the lake and there is a project underway to control them through trapping. Pine Lake has a car top boat launch at the public park.

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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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