San Andreas Lake
San Andreas Lake in San Mateo County, California is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 486 acres.
- Area
- 486 acres
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Why San Andreas Lake has no grade
We grade a lake only when the monitoring record supports a letter: 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 San Andreas Lake, no water-quality sampling on record for this lake.
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.
San Andreas Lake is a 486-acre lake in San Mateo County, California.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled recent years. Grade methodology: LakeQuality methodology.
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Swimming Safety
Not ratedElevated nutrients
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for San Andreas Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Trophic State Index: undefined.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) |
Where to stay near San Andreas Lake
Compare lakeside cabins, hotels, and vacation rentals near San Andreas Lake in San Mateo 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 San Andreas Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 486 acres |
No bathymetric survey has been published for San Andreas Lake, so its depth is not documented here.
Fishing San Andreas Lake
Nearby Lakes in San Mateo County
Frequently asked questions about San Andreas Lake
Where is San Andreas Lake?
- San Andreas Lake is a lake in San Mateo County, California. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for San Andreas Lake?
- San Andreas Lake in San Mateo County, California is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 486 acres.
Is San Andreas Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. San Andreas Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
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Where this data comes from
Measurements for San Andreas Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.