Union Grove Lake
Tama County, WisconsinHypereutrophic
Union Grove Lake is a 117-acre highly nutrient-loaded hypereutrophic lake in Tama County, IA. Water quality is graded F based on 2 sampling years through 2024. Compared to the 2 other monitored lakes in Tama County, Union Grove Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-08-27. Grade methodology: LakeGrade methodology.
Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 1.6 ft of visibility. Chlorophyll-a: 88.5 µg/L. Trophic State Index: 73.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 88.5 µg/L | F |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 117 acres |
Location
County Ranking
Ranked #2 of 3 lakes in Tama County
Cleaner Lakes Within 30 Miles
Union Grove Lake holds Grade F. 3 nearby lakes hold higher grades.
- BSand LakeMarshall County · 9.1 mi · Two grade letters higher (F → B)
- CGreen Castle LakeMarshall County · 15.3 mi · Two grade letters higher (F → C)
- DOtter Creek LakeTama County · 11.7 mi · Higher grade (F → D)
Nearby Lakes in Tama County
More Wisconsin Lake Rankings
Other Grade F Lakes in Wisconsin
Hypereutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Union Grove Lake is a man-made reservoir impounded by the Union Grove Lake Dam (completed 1920), built primarily for recreation on the DEER CREEK; earth-type dam, 29 ft tall and 1,205 ft long.
- Surface area
- 117 ac
- Normal storage
- 770 ac-ft
- Max storage
- 2,120 ac-ft
- Drainage area
- 11 sq mi
- Hazard class
- Significant
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA01373 · Operator website
EPA Impairment Status
Union Grove Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 02-IOW-724 · Official waterbody report
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-08-27
Monitoring stations: 1