Hetch Hetchy Reservoir
Hetch Hetchy Reservoir in Tuolumne County, California is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 2008 acres.
- Area
- 2,008 acres
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Why Hetch Hetchy Reservoir 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 Hetch Hetchy Reservoir, 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.
Hetch Hetchy Reservoir is a 2,008-acre lake in Tuolumne 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 Hetch Hetchy Reservoir
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 Hetch Hetchy Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Hetch Hetchy Reservoir in Tuolumne 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 Hetch Hetchy Reservoir
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 2,008 acres |
No bathymetric survey has been published for Hetch Hetchy Reservoir, so its depth is not documented here.
Fishing Hetch Hetchy Reservoir
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Frequently asked questions about Hetch Hetchy Reservoir
Where is Hetch Hetchy Reservoir?
- Hetch Hetchy Reservoir is a lake in Tuolumne 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 Hetch Hetchy Reservoir?
- Hetch Hetchy Reservoir in Tuolumne County, California is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 2008 acres.
Is Hetch Hetchy Reservoir safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Hetch Hetchy Reservoir 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 Hetch Hetchy Reservoir come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.