Updated Aug 2026
California Lake Water Quality
1,078 lakes across 57 counties, 109 with a recent water-quality reading.
Lake Map
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New water-quality readings for California lakes as SWRCB publishes them. Unsubscribe anytime.
Where to stay near California's cleanest lakes
Cabins, resorts, and vacation rentals around Folsom Lake (Placer County, CA) and the other cleanest California lakes pinned on the map. Live availability and prices.
Top-rated places to stay near Folsom Lake (Placer County, CA)
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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California fishing & travel
Reservoirs in California
View all 22 reservoirs →22 of 1,078 California lakes (2%) are man-made reservoirs in the USACE National Inventory of Dams. 18 carry a High or Significant hazard rating. The oldest matched dam dates to 1869.
EPA-Impaired Lakes in California
View all 164 impaired lakes →164 of 1,078 California lakes (15%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 43 have an approved Total Maximum Daily Load (TMDL) restoration plan.
California Fishing & Recreation
Licenses, regulations, records, and where to fish across California.
Counties
All 57 California counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of lakes, or pick a different state.
California lists 1,078 lakes across 57 counties, 109 of them with a recent water-quality reading. Most of that sampling flows through monitoring run by the California State Water Resources Control Board, which feeds state, federal, and volunteer measurements into the EPA Water Quality Portal. The remainder are here because they are real named lakes, not because anyone has sampled them recently.
Goose Lake is the largest lake in this index at about 93,048 acres, one of 167 here that clear 500 acres. The rest run smaller, and small and shallow is where nutrient loading shows up first, because there is less water to dilute it and the bottom sediment stays within reach of the sun. The county with the lowest nutrient and algae readings on average is Plumas. The gap between counties is large enough that a single figure for California lake water quality hides real local variation.
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of lakes that fit, with the water quality behind each one.
Source: EPA National Aquatic Resource Surveys and the EPA Water Quality Portal.
More on lake water quality
A data snapshot of the lakes we track: the clearest and the greenest states, and where the water is improving.
How nutrient and algae readings are read against EPA ecoregion condition classes, what each class means in the water, and why a clean reading is not a clearance.
The clearest lakes in America, ranked by measured Secchi depth in feet from EPA monitoring data — and why the famously clear lakes are missing.