Lake County Lake Quality

California, 55 lakes, average grade D (Nutrient-rich)

Lake County has 55 graded lakes, enough that within-county variation matters as much as the county average. Some are deep glacial basins, others are shallow agricultural-watershed waters, and the grade distribution reflects that mix. On average, Lake County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.

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. Glenhaven Lake (A) is the cleanest in the county.

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Quick Answers for Lake County

Cleanest lakes in Lake County →Cleanest lakes in California →Safest swimming lakes in California →

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

All Lakes in Lake County

55 lakes · 26 graded, 29 not rated26 graded lakes · 29 not rated, hidden

Include not-rated lakes (29)

#	Lake	Grade	Clarity	Phosphorus	Algae	Trophic	Access
1	AGlenhaven LakeLake	A	No recent samples	No recent samples	5.7 µg/L	No recent samples	Not recorded
2	ARumsey Slough by the Old Bridge LakeLake	A	No recent samples	No recent samples	4.6 µg/L	No recent samples	Not recorded
3	CBuckingham Point LakeLake	C	No recent samples	No recent samples	8.7 µg/L	No recent samples	Not recorded
4	CFishing Point LakeLake	C	1.6 ft	No recent samples	8.5 µg/L	No recent samples	Not recorded
5	CRumsey Slough Mouth LakeLake	C	1.6 ft	No recent samples	7.2 µg/L	No recent samples	Not recorded
6	CWest Corner of Big Valley Rancheria Marina LakeLake	C	2.1 ft	No recent samples	8.6 µg/L	No recent samples	Not recorded
7	DA Bridge Within the Oaks Keys on Blue Heron Drive LakeLake	D	No recent samples	No recent samples	20 µg/L	No recent samples	Not recorded
8	DAt End of El-Em St. on Elem Indian Colony LakeLake	D	No recent samples	No recent samples	16.3 µg/L	No recent samples	Not recorded
9	DBoat Ramp of Big Valley Rancheria Marina LakeLake	D	2.2 ft	No recent samples	9.7 µg/L	No recent samples	Not recorded
10	DClear Lake A Mooring laLake	D	No recent samples	165.5 µg/L	14 µg/L	No recent samples	Not recorded
11	DClear Lake A Mooring OaLake	D	No recent samples	253 µg/L	10.8 µg/L	No recent samples	Not recorded
12	DClear Lake A Mooring UaLake	D	No recent samples	138 µg/L	8.7 µg/L	No recent samples	Not recorded
13	DClear Lake OaksLake	D	No recent samples	No recent samples	16.7 µg/L	No recent samples	Not recorded
14	DCounty Park LakeLake	D	No recent samples	No recent samples	14.4 µg/L	No recent samples	Not recorded
15	DEast Corner of Big Valley Rancheria Marina LakeLake	D	2 ft	No recent samples	9.8 µg/L	No recent samples	Not recorded
16	DHorseshoe Bend LakeLake	D	No recent samples	No recent samples	20.3 µg/L	No recent samples	Not recorded
17	DJago Bay LakeLake	D	No recent samples	No recent samples	9.6 µg/L	No recent samples	Not recorded
18	DLand'S End Slough LakeLake	D	1.5 ft	No recent samples	10.7 µg/L	No recent samples	Not recorded
19	DMarina Lake SiteLake	D	2 ft	No recent samples	18.6 µg/L	No recent samples	Not recorded
20	DOld Lakeport Tnt RestaurantLake	D	No recent samples	No recent samples	17.5 µg/L	No recent samples	Not recorded
21	DRodman Slough LakeLake	D	No recent samples	No recent samples	12.6 µg/L	No recent samples	Not recorded
22	DShady Acres Campground Now Called Clearlake CampgroundLake	D	No recent samples	No recent samples	13.4 µg/L	No recent samples	Not recorded
23	DSolar Bee of Big Valley Rancheria Marina LakeLake	D	2.3 ft	No recent samples	14.4 µg/L	No recent samples	Not recorded
24	DTule Boat Launch LakeLake	D	2.3 ft	No recent samples	27.5 µg/L	No recent samples	Not recorded
25	DWestern Boundary LakeLake	D	1.5 ft	No recent samples	13 µg/L	No recent samples	Not recorded
26	FLake Shore Adjacent To New Tnt Restaurant on ShorelineLake	F	No recent samples	No recent samples	108.9 µg/L	No recent samples	Not recorded
	NRBlue LakesLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRBridge on Blue Heron Street LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRClear Lake A Redbud Park A ClearlakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRClear Lake A Stubbs IslandLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRClear Lake A Sulphur Bank MineLake	NR	No recent samples	No recent samples	73.6 µg/L	No recent samples	Not recorded
	NRClearlake OaksLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRElem Colony LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRFrog PondLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRGlenhaven Private Property LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHerman Impoundment LakeLake	NR	No recent samples	3 µg/L	1.5 µg/L	No recent samples	Not recorded
	NRHighland Springs ReservoirLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHousing PondLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRKayan PondLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRKeeling Park Nice LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLake PillsburyLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLily Cove LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLower Blue LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLucerne Harbor Park LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRNorth Pit LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRRedbud Park LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRRumsey Slough End LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRRumsey Slough Mid LakeLake	NR	No recent samples	No recent samples	4.6 µg/L	No recent samples	Not recorded
	NRSchindler Creek Bridge LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRState Dwr-Lower Arm of Clear LakeLake	NR	29.2 ft	No recent samples	No recent samples	No recent samples	Not recorded
	NRState Dwr-Oaks Arm of Clear LakeLake	NR	36.7 ft	No recent samples	No recent samples	No recent samples	Not recorded
	NRState Dwr-Upper Arm of Clear LakeLake	NR	5.6 ft	No recent samples	No recent samples	No recent samples	Not recorded
	NRSulphur Bank Mercury Mine LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRTule Lake A Upper LakeLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRTule PondLake	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded

NR = not rated: the monitoring record does not meet the evidence bar for a grade. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.

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