Cache County Lake Quality
Utah, 6 lakes, average grade B (Good)
Cache County holds 6 monitored lakes. With a sample that small the county-level summary describes those specific waters, not necessarily every water body in the county. 5 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. With an average grade of B, Cache County sits comfortably above the Utah median.
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. Newton Reservoir (A) is the cleanest in the county.
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Quick Answers for Cache County
Planning a trip? Check special fishing regulations for Newton Reservoir — or check the official Utah fishing regulations.
All Lakes in Cache County
6 lakes · 5 graded, 1 not rated5 graded lakes · 1 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | ANewton ReservoirCache | A | 15.4 ft | 26 µg/L | 1.7 µg/L | No recent samples | Not recorded |
| 2 | AHyrum ReservoirCache | A | 6.9 ft | 17.9 µg/L | 2.2 µg/L | No recent samples | ✓ Public |
| 3 | AThird Dam LakeCache | A | 4.3 ft | 10.4 µg/L | 1.1 µg/L | No recent samples | Not recorded |
| 4 | CPorcupine ReservoirCache | C | 8.5 ft | 13.3 µg/L | 3.8 µg/L | No recent samples | Not recorded |
| 5 | DCutler ReservoirCache | D | 1.2 ft | 109 µg/L | 17.4 µg/L | No recent samples | Not recorded |
| NRCutler ReservoirCache | NR | 1 ft | 100 µg/L | 11.2 µg/L | 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 Utah
See how Cache 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.