Nine Eagles Lake
Decatur County, WisconsinMesotrophic
Nine Eagles Lake is a 59-acre mesotrophic lake in Decatur County, IA. Water quality is graded A based on 2 sampling years through 2024. Compared to the 2 other monitored lakes in Decatur County, Nine Eagles Lake ranks #1 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
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Good clarity, visible to about 11 ft. Chlorophyll-a: 3.3 µg/L. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 3.3 µg/L | A |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 59 acres |
Location
County Ranking
Ranked #1 of 3 lakes in Decatur County
Nearby Lakes in Decatur County
More Wisconsin Lake Rankings
Other Grade A Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Nine Eagles Lake is a man-made reservoir impounded by the Nine Eagles Park Lake Dam (completed 1930), built primarily for recreation on the TR-THOMPSON RIVER; earth-type dam, 53 ft tall and 1,000 ft long.
- Surface area
- 59 ac
- Normal storage
- 840 ac-ft
- Max storage
- 1,560 ac-ft
- Drainage area
- 1.77 sq mi
- Hazard class
- Significant
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA01340 · Operator website · Matched by proximity (0.12 km)
EPA Impairment Status
Nine Eagles 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 05-GRA-1361 · 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: 2024-09-15
Monitoring stations: 1