Crook County Lake Quality
Oregon, 13 lakes, average grade D (Nutrient-rich)
Crook County has 13 monitored lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. 2 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. On average, Crook County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Prineville Reservoir (D); the most-stressed is Prineville Reservoir (D).
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Quick Answers for Crook County
Planning a trip? Check special fishing regulations for Prineville Reservoir — or check the official Oregon fishing regulations.
All Lakes in Crook County
13 lakes · 2 graded, 11 not rated2 graded lakes · 11 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | DPrineville ReservoirCrook | D | No recent samples | No recent samples | 7.5 µg/L | No recent samples | ✓ Public |
| 2 | DOchoco Lake County Park Boat RampCrook | D | No recent samples | No recent samples | 12 µg/L | No recent samples | ✓ Public |
| NRHorse Heaven Reservoir Along East ShoreCrook | NR | No recent samples | 40 µg/L | No recent samples | No recent samples | Not recorded | |
| NRPringle Flat ReservoirCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRRickmans Camp Creek Reservoir Number TwoCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRAntelope Flat ReservoirCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRHouston LakeCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NROchoco ReservoirCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRBarnes Butte ReservoirCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRDry Creek ReservoirsCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRAllen Creek ReservoirCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRGrindstone ReservoirCrook | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRLillard ReservoirCrook | 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 Oregon
See how Crook 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.