Unionville Lake
Putnam County, WisconsinHypereutrophic
Unionville Lake is a 75-acre highly nutrient-loaded hypereutrophic lake in Putnam County, MO. Water quality is graded F based on 3 sampling years through 2020.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2020-08-25. 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. Phosphorus level: 129.5 µg/L. Chlorophyll-a: 57.5 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | F |
| Phosphorus | 129.5 µg/L | F |
| Chlorophyll-a (Algae) | 57.5 µg/L | F |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 75 acres |
Location
County Ranking
Ranked #1 of 1 lakes in Putnam County
Cleaner Lakes Within 30 Miles
Unionville Lake holds Grade F. 5 nearby lakes hold higher grades.
- BMilan Lake NorthSullivan County · 21.1 mi · Two grade letters higher (F → B)
- CHazel Creek Lk. LakeAdair County · 25.2 mi · Two grade letters higher (F → C)
- CHazel Creek Lk. LakeAdair County · 25.1 mi · Two grade letters higher (F → C)
- DHazel Creek Lk. East Fork LakeAdair County · 26.8 mi · Higher grade (F → D)
- FElmwood LakeSullivan County · 19.6 mi · Higher overall water quality score
Nearby Lakes in Putnam County
More Wisconsin Lake Rankings
Other Grade F Lakes in Wisconsin
St. Louis County · Clarity: 1.6 ft
Jackson County · Clarity: 2 ft
St. Charles County · Clarity: 2.3 ft
St. Francois County · Clarity: 1.1 ft
Saline County · Clarity: 2.3 ft
Polk County · Clarity: 1.2 ft
Hypereutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Unionville Lake is a man-made reservoir impounded by the Lake Mahoney Dam (completed 1941), built primarily for recreation on the TR-BLACKBIRD CREEK; earth-type dam, 30 ft tall.
- Surface area
- 75 ac
- Normal storage
- 450 ac-ft
- Max storage
- 1,204 ac-ft
- Drainage area
- 1,900 sq mi
- Hazard class
- Low
- Owner
- UNIONVILLE,MO
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO10382 · Operator website · Matched by proximity (0.11 km)
EPA Impairment Status
Unionville Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MO_7154.00 · 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: 2020-08-25
Monitoring stations: 1