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

Larimer County Lake Quality

Colorado, 91 lakes, average grade B (Good)

Larimer County has 91 monitored 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 measurements reflect that mix. 8 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. The county-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.

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. Lon Hagler Reservoir (A) is the cleanest in the county.

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Quick Answers for Larimer County

Cleanest lakes in Larimer County →Cleanest lakes in Colorado →Safest swimming lakes in Colorado →

Planning a trip? Check special fishing regulations for Lon Hagler Reservoir — or check the official Colorado fishing regulations.

All Lakes in Larimer County

91 lakes · 8 graded, 83 not rated8 graded lakes · 83 not rated, hidden

Include not-rated lakes (83)

#	Lake	Grade	Clarity	Phosphorus	Algae	Trophic	Access
1	ALon Hagler ReservoirLarimer	A	4.6 ft	20 µg/L	3.8 µg/L	No recent samples	✓ Public
2	ABoyd LakeLarimer	A	4.6 ft	20 µg/L	5.1 µg/L	No recent samples	✓ Public
3	ADouglas ReservoirLarimer	A	4.1 ft	11 µg/L	2.5 µg/L	No recent samples	✓ Public
4	BChambers LakeLarimer	B	5.1 ft	11.5 µg/L	5 µg/L	No recent samples	Not recorded
5	CThe Loch Hypolimnion LakeLarimer	C	No recent samples	No recent samples	2.8 µg/L	No recent samples	Not recorded
6	CThe Loch Surface LakeLarimer	C	No recent samples	No recent samples	3.4 µg/L	No recent samples	Not recorded
7	DDowdy LakeLarimer	D	8.2 ft	11.5 µg/L	6.2 µg/L	No recent samples	Not recorded
8	DSky Pond HypolimnionLarimer	D	No recent samples	No recent samples	4.1 µg/L	No recent samples	Not recorded
	NRTimnath ReservoirLarimer	NR	5.6 ft	16.5 µg/L	10.7 µg/L	No recent samples	Not recorded
	NRCarter ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NREaton ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRJohnson ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRUpper Camp LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRPanhandle ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHiawatha LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRComanche ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLaramie LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRBarnes Meadow ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRPeterson LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRJoe Wright ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLong Draw ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHourglass ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRCrystal LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRInkwell LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRArrowhead LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRBlue Mountain ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRPinewood LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRFlatiron ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRMariano ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	NRHertha ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRColeman ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLonetree ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	NRHandy ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLoveland ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRBerthoud ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRSunnyslope ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRBacon LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRChapman ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRSouth Side ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRRyan Gulch ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRRist Benson ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRCemetery LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLake LovelandLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHouts ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NREqualizer LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHeinricy LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRUpper Hoffman LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRWesterdoll LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHorseshoe LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRNelson ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRDuck LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRDonath LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRGeorge Rist ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLake EstesLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRMarys LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRParvin LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRSeaman ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRPark Creek ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRBoxelder Reservoir Number ThreeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRWasson ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRMiners LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRDry Creek ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRBee LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRDemmel LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRWindsor ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRElder ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLindenmeier LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRLong PondLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRRichard Lake Reservoir Number SixLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRTerry LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRDixon ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRKluver ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRCurtis LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRWatson LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRClaymore LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRCollege LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHorsetooth ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRDixon ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRRobert Benson LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRNelson ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRWarren LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRPortner ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRFossil Creek ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRKitchel LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRSouth Gray ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRNorth Gray ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRCobb LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHinkley LakeLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRClark ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRIndian Creek ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	NRHalligan ReservoirLarimer	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded

NR = not rated: there is not enough recent sampling to support a letter. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.

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Other Counties in Colorado

Pueblo County

15 lakes · Avg grade A

Jackson County

22 lakes · Avg grade A

Montrose County

6 lakes · Avg grade A

Moffat County

8 lakes · Avg grade A

Jefferson County

29 lakes · Avg grade B

San Juan County

8 lakes · Avg grade B

See how Larimer County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all United States (49 states), Canada (Ontario and Québec), and 38 other country hubs..

Source: EPA National Aquatic Resource Surveys, 2026.