Big Hollow Lake
Des Moines County, WisconsinEutrophic
Big Hollow Lake is a 178-acre productive, nutrient-rich eutrophic lake in Des Moines County, IA. Water quality is graded F based on 2 sampling years through 2024. Compared to the 1 other monitored lakes in Des Moines County, Big Hollow Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-09-16. 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 1.8 ft of visibility. Chlorophyll-a: 46 µg/L. Trophic State Index: 68.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.8 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 46 µg/L | F |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 178 acres |
Location
County Ranking
Ranked #1 of 2 lakes in Des Moines County
Cleaner Lakes Within 30 Miles
Big Hollow Lake holds Grade F. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Des Moines County
More Wisconsin Lake Rankings
Other Grade F Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Big Hollow Lake is a man-made reservoir impounded by the Big Hollow Dam (completed 2008), built primarily for recreation on the Big Hollow Creek; earth-type dam, 60 ft tall and 795 ft long.
- Surface area
- 178 ac
- Normal storage
- 3,046 ac-ft
- Max storage
- 5,942 ac-ft
- Drainage area
- 7.5 sq mi
- Hazard class
- Significant
- Owner
- Des Moines County Conservation Board
Source: USACE National Inventory of Dams, NID ID IA03551 · Operator website
EPA Impairment Status
Big Hollow Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 02-ICD-6496 · 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: 2024-09-16
Monitoring stations: 1