La Plata County Lake Quality
Colorado, 4 lakes, average grade A (Excellent)
Only 4 lakes in La Plata County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. On average, La Plata County lakes grade an A. That puts it near the top of the {{stateName}} 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. Lake Nighthorse (A) is the cleanest in the county.
Quick Answers for La Plata County
Planning a trip? Check special fishing regulations for Lake Nighthorse — or check the official Colorado fishing regulations.
All Lakes in La Plata County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Lake Nighthorse | A | 18.7 ft | - |
| 2 | Upper Sunlight Lake | A | - | 5 µg/L |
| 3 | Upper Grizzly Lake | A | - | 10 µg/L |
| 4 | Haviland Lake | B | 13.8 ft | - |
Other Counties in Colorado
See how La Plata County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 12 states.
Where to stay near La Plata County
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Source: EPA National Aquatic Resource Surveys, 2026.