Lake
Thurston County, WashingtonView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from A at the last regrade
- Mesotrophic
- Impaired · Nuisance exotic species
- #2 of 16 in the county
- 19 ft max depth
- Public access
Lake in Thurston County, Washington has a water quality grade of C (Fair). Phosphorus: 8.5 µg/L. Chlorophyll-a (algae): 3 µg/L.
- Max depth
- ~19 ft est.
- Type
- Mesotrophic
- Phosphorus
- 8.5 µg/L
- Chlorophyll-a
- 3 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Lake’s letter
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Lake is a mesotrophic lake in Thurston County, Washington with an estimated average depth of about 19 feet. Water quality is graded C based on 1 sampling years through 2021. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 15 other monitored lakes in Thurston County, Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, WA Ecology, last sampled 2021-10-20. Grade methodology: LakeQuality methodology.
What Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Camping1 public campground nearby
Swimming Safety
Grade onlyModerate
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The C is nutrients and algae, not a swimming clearance. Lake is listed impaired under Clean Water Act §303(d) (IR 4C) for nuisance exotic species. Check local advisories before you swim.
Water Quality Grade: C (Fair)
No clarity data. Phosphorus 8.5 µg/L. Chlorophyll-a 3 µg/L. TSI 38. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 8.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 3 µg/L | Fair |
| Trophic State Index (TSI) | 38 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~19 ft est. |
| Average Depth | ~14 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Washington has not published bathymetry for Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Millersylvania State ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Lake
- Millersylvania State Park Campground0.5 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Fishing Lake
Water Quality Trend: ↑ Improving
Based on 8 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | → Stable | -0.11 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.11 µg/L/yr | 8 |
EPA Impairment Status
Lake is officially listed as impaired under Clean Water Act §303(d) in the 2018 EPA reporting cycle (IR category 4C).
Causes of impairment
Source: EPA ATTAINS assessment unit WA17100103000945_001_001 · Official waterbody report
County Ranking
Ranked #2 of 16 lakes in Thurston County
Nearby Lakes in Thurston County
Frequently asked questions about Lake
Where is Lake?
- Lake is a lake in Thurston County, Washington. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake?
- Lake in Thurston County, Washington has a water quality grade of C (Fair). Phosphorus: 8.5 µg/L. Chlorophyll-a (algae): 3 µg/L.
Is Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Lake is listed impaired under Clean Water Act §303(d) (IR 4C) for nuisance exotic species. Check local advisories before you swim.
How deep is Lake?
- No published bathymetric survey covers Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 19 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Lake?
- Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Millersylvania State Park. Public access is listed as yes.
Are there campgrounds on Lake?
- Lake has 1 public campground from USGS The National Map within 5 km, including Millersylvania State Park Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Lake across LakeQuality
More Washington Lake Rankings
Other Grade C Lakes in Washington
Mesotrophic Lakes in Washington
Where this data comes from
85 measurements from 1 monitoring station, 2012–2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Thurston County Health Department
THURSTONCOUNTY85 samples · 2012–2021
Analytical methods
- External files contain methodological data
- Fluorometric determination of chlorophyll a in presence of pheophytin
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles