Warren County Lake Quality
Wisconsin, 16 lakes, average grade C (Fair)
Warren County's 16 graded lakes fall in the moderate-density bracket for Missouri. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. Warren County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
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. Alpine Lake (A) is the cleanest in the county.
Quick Answers for Warren County
Planning a trip? Check special fishing regulations for Alpine Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Warren County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Alpine Lake | A | 12.6 ft | - | 7 µg/L |
| 2 | Lake Konstanz | B | 7.7 ft | - | 7 µg/L |
| 3 | Whippoorwill Lake | B | 5 ft | - | 13.8 µg/L |
| 4 | Sherwood Lake Nr. Dam | B | 5.9 ft | - | 14.3 µg/L |
| 5 | Castlenovo Lake | B | 6 ft | - | 16.8 µg/L |
| 6 | Sherwood Lake | B | 4.9 ft | - | 17.8 µg/L |
| 7 | Innsbrook Lake Nr. Dam | B | 5.2 ft | - | 17 µg/L |
| 8 | Aspen Lake Along Southern Arm | C | 3.8 ft | - | 20.8 µg/L |
| 9 | Lake Lucern | C | 5.2 ft | - | 25.8 µg/L |
| 10 | Red Fox Lake | C | 3.3 ft | - | 40 µg/L |
| 11 | Sugar Hollow Lake | D | 3.3 ft | - | 38 µg/L |
| 12 | Robin Hood Lakes | D | 3 ft | - | 43 µg/L |
| 13 | Lake Eleanor | D | 3 ft | - | 45 µg/L |
| 14 | Sugar Hollow Lake | D | 3.3 ft | - | 31.5 µg/L |
| 15 | Lake Eleanor | D | 2.8 ft | - | 46.5 µg/L |
| 16 | Robin Hood Lake | D | 3 ft | - | 58 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.