Thayer Lake
Union County, WisconsinEutrophic
Thayer Lake is a 14-acre productive, nutrient-rich eutrophic lake in Union County, IA. Water quality is graded D based on 2 sampling years through 2024. Compared to the 5 other monitored lakes in Union County, Thayer Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-09-15. Grade methodology: LakeGrade methodology.
Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Murky, only visible to about 3.5 ft. Chlorophyll-a: 34.3 µg/L. Trophic State Index: 62.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.5 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 34.3 µg/L | F |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 14.1 acres |
Location
County Ranking
Ranked #2 of 6 lakes in Union County
Nearby Lakes in Union County
More Wisconsin Lake Rankings
Other Grade D Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Thayer Lake is a man-made reservoir impounded by the Thayer Lake Dam (completed 1930), built primarily for recreation on the TR-FOUR MILE CREEK; earth-type dam, 30 ft tall and 590 ft long.
- Surface area
- 14.1 ac
- Normal storage
- 91 ac-ft
- Max storage
- 222 ac-ft
- Drainage area
- 0.79 sq mi
- Hazard class
- Low
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA01377 · Operator website
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-15
Monitoring stations: 1