Our website is changing! Starting March 31, 2023 our website will look different, but we're working hard to make sure you can still find what you need.  
King County logo
Lake Photo Image
Go to another lake:

Vital Statistics

Watershed Area 419 acres
Lake surface area 34 acres
Maximum depth feet
Mean depth feet
Public Park No
Boat Ramp Yes
Fish Present NA


Volunteer monitoring occurred at Panther Lake in the mid 1980s, with two other years, 1996 and 2000 measured since then. The data indicate this lake is high in primary productivity (eutrophic) with fair water quality. The lake is shallow, and thermal stratification does not remain established in summer, so the water continues to circulate throughout the entire lake. Nitrogen to phosphorus ratios were above 20:1 through the summer, which generally favors other algae over bluegreens.

Panther Lake has a public access boat launch, but much of the lake surface is covered by water lilies, which hampers some beneficial uses. Residents should watch the nearshore environment for infestations of Brazilian elodea or other noxious weeds.

Panther Lake data were collected using two different locator IDs. We are not sure if those were from the same location, and it may not be advisable to combine them for trend analyses. Until we can figure out more, we are keeping those datasets separate a

Back to top


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

Back to top

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).

Back to top

Reports and Related Links

Back to top
For questions about lakes in King County, please contact lakes@kingcounty.gov or call the Water and Land Resources Division front desk at 206-477-4800.