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

St. Lawrence County Lake Quality

New York, 103 lakes — no lake here has enough monitoring data for a grade

St. Lawrence County in New York carries 103 monitored lakes — one of the lake-richer counties in our dataset. Coverage that dense usually reflects active lake-association sampling alongside state-agency monitoring. No lake in St. Lawrence County has enough sampling behind it for an A–F grade yet. The 103 monitored lakes below carry whatever clarity, phosphorus, and chlorophyll-a measurements exist.

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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Quick Answers for St. Lawrence County

Cleanest lakes in St. Lawrence County →Cleanest lakes in New York →Safest swimming lakes in New York →

Planning a trip? Check special fishing regulations for Silver Lake — or check the official New York fishing regulations.

All Lakes in St. Lawrence County

103 lakes · 0 graded, 103 not rated0 graded lakes · 103 not rated, hidden

Include not-rated lakes (103)

Lake	Grade	Clarity	Phosphorus	Algae	Trophic	Access
NRSilver LakeSt. Lawrence	NR	15.1 ft	No recent samples	No recent samples	No recent samples	✓ Public
NRUpper LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLake OzoniaSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRWeller PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRSterling PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRClear PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRFive Falls ReservoirSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRSouth Colton ReservoirSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRRainbow Falls ReservoirSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRJoe Indian PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRBlake Falls ReservoirSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRBarney PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRStark Falls ReservoirSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRKildare PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRJordan LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRAmber LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRDeer PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRWindfall PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRCatamount PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRMassawepie LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRHorseshoe PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLong PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRTown Line PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRDeer PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRJocks PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRSampson PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRGrass River FlowSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRPleasant LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRClear PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRChandler PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLeonard PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRCrooked LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRCarry Falls ReservoirSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLong PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRPine MarshSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRTracy PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRTooley PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRCook PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRMoosehead PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRGreenfield PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLong PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRRound PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRPortaferry LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRBoyd PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRClear LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRWarm Brook FlowSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRArbuckle PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRGreen PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLower LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRHickory LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRMud LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRBlack LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRPleasant LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRMud LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRYellow LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRGrass LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRSylvia LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRMud PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRHuckleberry LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRWolf LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRChub LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRTrout LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRCedar LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRClear LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRBonner LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRTwin PondsSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRPine Hill PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRJones PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRStreeter LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLong LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRRound LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRDry Timber LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRRock LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLong LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRSucker LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRTwin LakesSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRStar LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRMuskrat PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLost PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRChaumont PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRHeath PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NROtter PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRSpring PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRHornet PondsSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NROtter PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLake MarianSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRScott PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRBassout PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NROlmstead PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRCranberry LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRBurntbridge PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRDog PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRPanther PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NREagle Crag LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRMount Arab LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRBridge Brook PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRHorseshoe LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRHitchins PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLows LakeSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLong PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRLittle Trout PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRTrout PondSt. Lawrence	NR	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
NRRaquette PondSt. Lawrence	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 New York

Seneca County

4 lakes · Avg grade A

Hamilton County

198 lakes · Avg grade A

Herkimer County

110 lakes · Avg grade A

Essex County

129 lakes · Avg grade A

Lewis County

33 lakes · Avg grade B

Franklin County

134 lakes · Avg grade C

See how St. Lawrence 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, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..

Source: EPA National Aquatic Resource Surveys, 2026.