Lower Blue Lake
Lower Blue Lake in Lake County, California is not rated for water quality — its monitoring record does not meet the evidence bar.
Why Lower Blue Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Lower Blue Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by your state environmental agency and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Lower Blue Lake is a lake in Lake County, California.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2023-10-05. Grade methodology: LakeGrade methodology.
Watch Lower Blue Lake water quality
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Lower Blue Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
No clarity data.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples |
Where to stay near Lower Blue Lake
Compare lakeside cabins, hotels, and vacation rentals near Lower Blue Lake in Lake County, California — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Lower Blue Lake
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Fishing Lower Blue Lake
EPA Impairment Status
Lower Blue Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit CAL5135402020091208155011 · Official waterbody report
Graded lakes near Lower Blue Lake
Lower Blue Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Lake County
Frequently asked questions about Lower Blue Lake
Where is Lower Blue Lake?
- Lower Blue Lake is a lake in Lake County, California. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for Lower Blue Lake?
- Lower Blue Lake in Lake County, California is not rated for water quality — its monitoring record does not meet the evidence bar.
Is Lower Blue Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Lower Blue Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Explore Lower Blue Lake across LakeGrade
More California Lake Rankings
Other Lakes in California
Where this data comes from
1 measurement from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- USGS California Water Science Center
USGS-CA1 sample · 2023
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