Where is Hetch Hetchy Reservoir?

Hetch Hetchy Reservoir is a lake in Tuolumne County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.

Hetch Hetchy Reservoir

Tuolumne County, California2,008 acresView map Directions

No nutrient or algae sampling on record from SWRCB for this lake.

Area

2,008 acres

Surface area

Shoreline

19.5 mi

Measured length

Impaired · Mercury
Limited data

See the measurements Directions Where to stay

Hetch Hetchy Reservoir in Tuolumne County, California has water-quality measurements published by SWRCB, shown here as reported. Surface area: 2008 acres.

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Hetch Hetchy Reservoir is a 2,008-acre lake in Tuolumne County, California.

Source: EPA Water Quality Portal sampling records, your state environmental agency. Methodology: how these readings are compared.

What Hetch Hetchy Reservoir is good for

From access and monitoring records, not editorial picks.

Big water2,008 acres

Swimming conditions

No reading

Limited data

Nutrient and algae readings are not a swimming clearance. Hetch Hetchy Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.

Whether Hetch Hetchy Reservoir 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.

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Water quality measurements for Hetch Hetchy Reservoir

These are the measurements SWRCB publishes for Hetch Hetchy Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.

No clarity data.

Ask about Hetch Hetchy Reservoir

Answers come straight from the public measurements and survey records on this page.

Lake Details

Surface area

2,008 acres

Shoreline

19.5 mi

No bathymetric survey has been published for Hetch Hetchy Reservoir, so its depth is not documented here.

Stays via Stay22

Stays 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

Prices for Oct 16–18, 4 adults. Change dates on the map below.

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Fishing Hetch Hetchy Reservoir

→ Hetch Hetchy Reservoir fishing regulations (limits, seasons, special rules)

EPA Impairment Status

Hetch Hetchy Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Mercury

Designated uses not supporting: Fish consumption, Other.

Source: EPA ATTAINS assessment unit CAL5366009120020418144307 · Official waterbody report

Nearby Lakes in Tuolumne County

Lake Vernon5.1 miView →Laurel Lake5.6 miView →Branigan Lake6.6 miView →Ardeth Lake7.9 miView →Bearup Lake8.5 miView →Edith Lake8.5 miView →

Frequently asked questions about Hetch Hetchy Reservoir

Where is Hetch Hetchy Reservoir?: Hetch Hetchy Reservoir is a lake in Tuolumne County, California. Its water-quality measurements are published by SWRCB and shown on this page as reported.
What is the water quality of Hetch Hetchy Reservoir?: Hetch Hetchy Reservoir in Tuolumne County, California has water-quality measurements published by SWRCB, shown here as reported. Surface area: 2008 acres.
Is Hetch Hetchy Reservoir safe to swim in?: Nutrient and algae readings are not a swimming clearance. Hetch Hetchy Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.