Rio Grande County Lake Quality
Colorado, 2 lakes, average grade D (Nutrient-rich)
Rio Grande County holds 2 monitored lakes. With a sample that small the county-level summary describes those specific waters, not necessarily every water body in the county. 1 of those lake carry an A–F grade. The county-level summary describes that subset, not every water body listed. On average, Rio Grande County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
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. Beaver Creek Reservoir (D) is the cleanest in the county.
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Quick Answers for Rio Grande County
Planning a trip? Check special fishing regulations for Beaver Creek Reservoir — or check the official Colorado fishing regulations.
All Lakes in Rio Grande County
2 lakes · 1 graded, 1 not rated1 graded lake · 1 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | DBeaver Creek ReservoirRio Grande | D | 6.2 ft | 36 µg/L | 8.4 µg/L | No recent samples | ✓ Public |
| NRSherman LakeRio Grande | 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
See how Rio Grande 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.