Hetch Hetchy Reservoir, CA

As of 2026-10-13, Hetch Hetchy Reservoir sits at 3761.41 ft. Over the past 30 days the level has fallen 13.08 ft.

The most recent reading at Hetch Hetchy Reservoir is 3761.41 ft (2026-10-13), sourced from the U.S. Geological Survey. Readings on this page refresh automatically as the agency publishes new data.

Readings for Hetch Hetchy Reservoir run from 3761.41 ft to 3807.03 ft over the 176 days on file, which begin 2026-04-21. That window is shorter than a year, so neither end is a record for the lake. A lake's range includes a full seasonal cycle, and this gauge has not yet published one.

Reservoir levels move for four main reasons: rainfall and runoff into the basin, releases through the dam for downstream water supply, power generation or flood control, evaporation during hot months, and seasonal drawdown schedules set by the operating agency. Hetch Hetchy Reservoir has fallen 13.08 ft over the past 30 days. For the operational reason on any given week, check the U.S. Geological Survey directly.

Year-over-year comparison is not available for Hetch Hetchy Reservoir yet. The published series on this page covers 176 days, from 3761.41 ft to 3807.03 ft. That is not long enough to describe the lake's historical range.