Beaver Lake
Dallas County, WisconsinEutrophic
Beaver Lake is a 34-acre productive, nutrient-rich eutrophic lake in Dallas County, IA. Water quality is graded F based on 2 sampling years through 2024. Compared to the 1 other monitored lakes in Dallas County, Beaver Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-09-30. 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 1.9 ft of visibility. Chlorophyll-a: 62.2 µg/L. Trophic State Index: 70.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.9 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 62.2 µg/L | F |
| Trophic State Index (TSI) | 70 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 34 acres |
Location
County Ranking
Ranked #2 of 2 lakes in Dallas County
Cleaner Lakes Within 30 Miles
Beaver Lake holds Grade F. 3 nearby lakes hold higher grades.
- BDale Maffitt ReservoirDallas County · 21.8 mi · Two grade letters higher (F → B)
- DSpringbrook LakeGuthrie County · 21.3 mi · Higher grade (F → D)
- DNodaway LakeAdair County · 22.4 mi · Higher grade (F → D)
Nearby Lakes in Dallas County
More Wisconsin Lake Rankings
Other Grade F Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Beaver Lake is a man-made reservoir impounded by the Beaver Lake Dam (completed 1990), built primarily for recreation on the TR-BEAR CREEK; earth-type dam, 43 ft tall and 666 ft long.
- Surface area
- 34 ac
- Normal storage
- 319 ac-ft
- Max storage
- 696 ac-ft
- Drainage area
- 1.61 sq mi
- Hazard class
- Significant
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA02498 · Operator website
EPA Impairment Status
Beaver 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 04-RAC-1182 · 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: 2024-09-30
Monitoring stations: 1