Western Boundary Lake
Lake County, CaliforniaView mapDirections
SWRCB publishes the water-quality measurements for Western Boundary Lake. Here is what has been measured.
- Impaired · Biotoxins
- Limited data
Western Boundary Lake in Lake County, California has water-quality measurements published by SWRCB, shown here as reported. Water clarity: 1.5 ft visibility. Chlorophyll-a (algae): 13 µg/L.
Western Boundary Lake is a lake in Lake County, California.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2026-04-30. Methodology: how these readings are compared.
Swimming conditions
No readingBacteria advisory
Nutrient and algae readings are not a swimming clearance. Western Boundary Lake is listed impaired under Clean Water Act §303(d) (IR 5) for biotoxins, mercury, metals (other than mercury), oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
Whether Western Boundary Lake is safe to swim in today is a call for the California State Water Resources Control Board and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Western Boundary Lake
These are the measurements SWRCB publishes for Western Boundary Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.5 ft of visibility. Chlorophyll-a 13 µg/L. TSI 64.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | 13µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 64 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Western Boundary Lake
Answers come straight from the public measurements and survey records on this page.
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Fishing Western Boundary Lake
EPA Impairment Status
Western Boundary Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Drinking water, Aquatic life, Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit CAL5135200019980814115549 · Official waterbody report
Nearby Lakes in Lake County
Frequently asked questions about Western Boundary Lake
Where is Western Boundary Lake?
- Western Boundary Lake is a lake in Lake County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.
What is the water quality of Western Boundary Lake?
- Western Boundary Lake in Lake County, California has water-quality measurements published by SWRCB, shown here as reported. Water clarity: 1.5 ft visibility. Chlorophyll-a (algae): 13 µg/L.
Is Western Boundary Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Western Boundary Lake is listed impaired under Clean Water Act §303(d) (IR 5) for biotoxins, mercury, metals (other than mercury), oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
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Where this data comes from
160 measurements from 2 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- Big Valley Band of Pomo Indians of the Big Valley Rancheria, California (Tribal)
CA_BVR160 samples · 2020–2026
Analytical methods
- Chlorophyll a
Monitoring station identifiers (2)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database