Dairyland Reservoir vs Island Lake
Water quality, depth, fish species, and recreation comparison.
Island Lake has a higher water quality grade (B, Good) than Dairyland Reservoir (F, Very Poor). Both are in Rusk County, Wisconsin.
Dairyland Reservoir and Island Lake are both in Wisconsin — a same-state head-to-head where the comparison comes down to lake-specific differences in depth, watershed, and monitoring history rather than the broader state-level water-quality regime. The grades are meaningfully apart: Island Lake grades a B while Dairyland Reservoir grades a F. That two-letter spread reflects real underlying differences — different watershed inputs, different depth profiles, or different monitoring rigor.
For a recreational visitor, the wider grade gap is decisive — Island Lake is the better water-quality choice. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?
Dairyland Reservoir
Very murky, less than 1.4 ft of visibility.
Island Lake
Moderate clarity, visible to about 7.7 ft.
Side-by-Side Metrics
| Metric | Dairyland Reservoir | Island Lake |
|---|---|---|
| Overall Grade | F (Very Poor) | B (Good) |
| Water Clarity | 1.4 ft | 7.7 ft |
| Phosphorus | No data | 15.4 µg/L |
| Chlorophyll-a (Algae) | No data | No data |
| Maximum Depth | - | - |
| Surface Area | 2.0K acres | 1.2K acres |
| Public Access | Unknown | Unknown |
| Fish Species | 0 | 0 |
| Trophic State | hypereutrophic | mesotrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Island Lake wins on overall water quality with a Grade B versus Dairyland Reservoir's Grade F. Water clarity: 7.7 ft vs 1.4 ft. For fishing diversity, Island Lake also leads with 0 species.