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LakeQuality
Late afternoon sun over Slim Lake, scattering a bright path across wind-textured water

Merced County Lake Quality

California, 13 lakes, measured by SWRCB

Merced County has 13 monitored lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. The 13 monitored lakes in Merced County carry whatever clarity, phosphorus, and chlorophyll-a readings SWRCB has published, shown as reported.

Most of the county's monitored lakes are shallow, under 50 feet, which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed.

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Where to stay near Merced County

Top-rated places to stay near Merced County

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Quick Answers for Merced County

Cleanest lakes in Merced County →Best swimming lakes in California →

Planning a trip? Check special fishing regulations for Big Buttonwillow Lake — or check the official California fishing regulations.

All Lakes in Merced County

13 lakes · 0 ranked on readings, 13 without enough sampling0 lakes ranked on readings · 13 without enough sampling, hidden

#LakeClarityPhosphorusAlgaeTrophicAccess
Big Buttonwillow LakeMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Big Water LakeMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Flat PondMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Kelsey ReservoirMercedNo recent samplesNo recent samples16.4 µg/LNo recent samplesNot recorded
Little Buttonwillow LakeMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Los Banos CreekMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Los Banos ReservoirMercedNo recent samplesNo recent samplesNo recent samplesNo recent samples✓ Public
Mud SloughMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
O'Neill ForebayMercedNo recent samplesNo recent samplesNo recent samplesNo recent samples✓ Public
San Luis Holding ReservoirMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
San Luis ReservoirMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Upper Ruth LakeMercedNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Yosemite LakeMercedNo recent samplesNo recent samplesNo recent samplesNo recent samples✓ Public

NR = no nutrient or algae reading on record. The measurements are published as the authority reports them. Where the data comes from.

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Other Counties in California

Plumas County

19 lakes

Amador County

12 lakes

Placer County

16 lakes

Butte County

16 lakes

Nevada County

35 lakes

Santa Clara County

13 lakes

Browse every California lake, or the full directory of lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..

Source: the California State Water Resources Control Board. See data sources.