Peterborough County Lake Quality
Ontario, 71 lakes, average grade A (Excellent)
Peterborough County has 71 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, Peterborough County lakes grade an A. That puts it near the top of the Ontario county ranking.
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. Anstruther Lake (A) is the cleanest in the county.
Quick Answers for Peterborough County
Planning a trip? Check special fishing regulations for Anstruther Lake — or check the official Ontario fishing regulations.
All Lakes in Peterborough County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Anstruther Lake | A | 16.4 ft | 6.2 µg/L |
| 2 | Belmont Lake | A | 17.1 ft | 7.2 µg/L |
| 3 | Big Cedar Lake | A | 16.4 ft | - |
| 4 | Buzzard Lake | A | 20 ft | 13.3 µg/L |
| 5 | Chandos Lake | A | 16.4 ft | 7.6 µg/L |
| 6 | Crystal Lake | A | 16.4 ft | 9.4 µg/L |
| 7 | Eels Lake | A | 17.1 ft | 5.7 µg/L |
| 8 | Jacks Lake | A | 16.4 ft | 8.4 µg/L |
| 9 | Julian Lake | A | 16.7 ft | 6.8 µg/L |
| 10 | Kasshabog Lake | A | 15.7 ft | 7.1 µg/L |
| 11 | Katchewanooka Lake | A | 16.4 ft | 16.4 µg/L |
| 12 | Lasswade Lake | A | 15.7 ft | 8.1 µg/L |
| 13 | Long Lake | A | 16.9 ft | 5.6 µg/L |
| 14 | Loon Call Lake | A | 15.1 ft | 12.2 µg/L |
| 15 | Methuen Lake | A | 16.9 ft | 7.6 µg/L |
| 16 | Oak Lake | A | 15.7 ft | 7 µg/L |
| 17 | Picard Lake | A | 18 ft | 6.7 µg/L |
| 18 | Salmon Lake | A | 24.8 ft | 6.3 µg/L |
| 19 | Sandy Lake | A | 15.1 ft | 6.4 µg/L |
| 20 | Upper Stoney Lake | A | 19 ft | 8 µg/L |
| 21 | White Lake | A | 16.1 ft | 9 µg/L |
| 22 | Cherry Lake | A | - | 7.7 µg/L |
| 23 | Coon Lake | A | - | 7.2 µg/L |
| 24 | Cox Lake | A | - | 5.4 µg/L |
| 25 | Minnow Lake | A | - | 11.6 µg/L |
| 26 | Raspberry Lake | A | - | 6.2 µg/L |
| 27 | Stoplog Lake | A | - | 9.5 µg/L |
| 28 | Triangle Lake | A | - | 6.6 µg/L |
| 29 | Vixen Lake | A | - | 12.4 µg/L |
| 30 | Cavendish Lake | A | - | 5.2 µg/L |
| 31 | Gold Lake | A | - | 4.2 µg/L |
| 32 | Pencil Lake | A | - | 6.3 µg/L |
| 33 | Rathbun Lake | A | - | 8.2 µg/L |
| 34 | Tallon Lake | A | - | 5.7 µg/L |
| 35 | Tallan Lake | A | 20 ft | 10.5 µg/L |
| 36 | Beaver Lake | A | 13 ft | 7.7 µg/L |
| 37 | Big Bald Lake | A | 12 ft | 11.9 µg/L |
| 38 | Bolger Lake | A | 14.1 ft | 14.9 µg/L |
| 39 | Catchacoma Lake | A | 10.8 ft | 5.2 µg/L |
| 40 | Clear Lake | A | 12.1 ft | 15.5 µg/L |
| 41 | Cordova Lake | A | 14.8 ft | 10.7 µg/L |
| 42 | Crab Lake | A | 11.5 ft | 9.7 µg/L |
| 43 | Fortescue Lake | A | 14.8 ft | 6.1 µg/L |
| 44 | Galloway Lake | A | 10.2 ft | 13.6 µg/L |
| 45 | Lanes Lake | A | 12.6 ft | 4.5 µg/L |
| 46 | Little Long Lake | A | 13.5 ft | 9 µg/L |
| 47 | Lovesick Lake | A | 14.8 ft | 19 µg/L |
| 48 | Lower Buckhorn Lake | A | 12.5 ft | 18.2 µg/L |
| 49 | Mississagua Lake | A | 14.8 ft | 6 µg/L |
| 50 | Round Lake | A | 13.1 ft | 9.1 µg/L |
| 51 | Stony Lake | A | 13.1 ft | 14.9 µg/L |
| 52 | West Twin Lake | A | 10.8 ft | 7.4 µg/L |
| 53 | White Lake | A | 14.1 ft | 12.8 µg/L |
| 54 | Wolf Lake | A | 13.5 ft | 8.4 µg/L |
| 55 | Dummer Lake | A | 15.7 ft | 22.4 µg/L |
| 56 | Jack Lake | A | 12.5 ft | 9.8 µg/L |
| 57 | Bass Lake | B | 9.8 ft | 11.6 µg/L |
| 58 | Bottle Lake | B | 9.2 ft | 10.1 µg/L |
| 59 | Bott'S Lake | B | 9.8 ft | 12 µg/L |
| 60 | Buckhorn Lake | B | 9.5 ft | 17.8 µg/L |
| 61 | Chemong Lake | B | 8.5 ft | 16.1 µg/L |
| 62 | Clydesdale Lake | B | 6.9 ft | 10.3 µg/L |
| 63 | Cold Lake | B | 7.9 ft | 7 µg/L |
| 64 | Loucks Lake | B | 15.7 ft | 49.8 µg/L |
| 65 | Pigeon Lake | B | 9.8 ft | 16.9 µg/L |
| 66 | Alder Lake | B | 9.8 ft | 9.8 µg/L |
| 67 | Rice Lake | B | 7.5 ft | 12 µg/L |
| 68 | Nogies Creek Lake | B | 5.2 ft | 12.4 µg/L |
| 69 | Little Bald Lake | B | 6.6 ft | 12.1 µg/L |
| 70 | Rice Lake | C | 5.1 ft | 23.6 µg/L |
| 71 | Shadow Lake | C | - | 46 µg/L |
Other Counties in Ontario
See how Peterborough County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 38 states.
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Source: EPA National Aquatic Resource Surveys, 2026.