Lake County Lake Quality
Colorado, 6 lakes, average grade C (Fair)
Lake County has 6 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. 4 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. The county average is C — the middle of the rubric, with one or two lakes pulling the average up or down depending on year.
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 Twin Lakes East (C); the most-stressed is Turquoise Reservoir (D).
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Quick Answers for Lake County
Planning a trip? Check special fishing regulations for Twin Lakes East — or check the official Colorado fishing regulations.
All Lakes in Lake County
6 lakes · 4 graded, 2 not rated4 graded lakes · 2 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | CTwin Lakes EastLake | C | 14.1 ft | 46 µg/L | 1.3 µg/L | No recent samples | Not recorded |
| 2 | CTwin Lakes WestLake | C | 11.5 ft | 46 µg/L | 0.7 µg/L | No recent samples | Not recorded |
| 3 | DTurquoise ReservoirLake | D | 16.1 ft | 46 µg/L | 2.1 µg/L | No recent samples | Not recorded |
| 4 | DTwin Lake West LowerLake | D | No recent samples | 46 µg/L | No recent samples | No recent samples | Not recorded |
| NRMount Elbert ForebayLake | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRTimberline LakeLake | 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.
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Other Counties in Colorado
See how Lake 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.