Fin And Feather Lake is a 16-acre productive, nutrient-rich eutrophic lake in Cerro Gordo County, Iowa. Water quality is graded F based on 2 sampling years through 2022. Overall water quality is declining over recent sampling years. Compared to the 3 other monitored lakes in Cerro Gordo County, Fin And Feather Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2022-09-12. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 2.3 ft of visibility. Chlorophyll-a: 42 µg/L. Trophic State Index: 66.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.3 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 42 µg/L | F |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 16 acres |
Where to stay near Fin And Feather Lake
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Fishing Fin And Feather Lake
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.1 m/yr | 3 |
| Chlorophyll-a | ↓ Declining | +6.1 µg/L/yr | 3 |
Water Temperature
Fin And Feather Lake averages about 76°F at the surface in summer, usually warmest in Jul (about 78°F) and coldest in Jun (about 72°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 9 field readings (2018–2022) via the EPA Water Quality Portal. See the full Fin And Feather Lake water temperature breakdown →
Location
County Ranking
Ranked #4 of 4 lakes in Cerro Gordo County
Cleaner Lakes Within 30 Miles
Fin And Feather Lake holds Grade F. 4 nearby lakes hold higher grades.
- ABlue Pit LakeCerro Gordo County · 2.9 mi · Two grade letters higher (F → A)
- BRudd LakeFloyd County · 15.1 mi · Two grade letters higher (F → B)
- DBlack Pit LakeCerro Gordo County · 3 mi · Higher grade (F → D)
- DClear LakeCerro Gordo County · 11.6 mi · Higher grade (F → D)
Nearby Lakes in Cerro Gordo County
Explore Fin And Feather Lake across LakeGrade
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Eutrophic Lakes in Iowa
More records, surveys & data sources
Reservoir Info (USACE NID)
Fin And Feather Lake is a man-made reservoir impounded by the Lake Fin-Feather Dam (completed 1972), built primarily for recreation on the TR-WINNEBAGO RIVER; earth-type dam, 25 ft tall and 1,200 ft long.
- Surface area
- 16 ac
- Normal storage
- 76 ac-ft
- Max storage
- 123 ac-ft
- Drainage area
- 0.22 sq mi
- Hazard class
- Low
- Owner
- Cerro Gordo County Conservation Board
Source: USACE National Inventory of Dams, NID ID IA00175 · Operator website · Matched by proximity (0.05 km)
EPA Impairment Status
Fin And Feather Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit IA 02-WIN-840 · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Fin And Feather Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Mason City, City Of StpMason City · 2.9 mi away · NPDES IA0057169MajorRecent violation
- Mason City, City Of WtpMason City · 3 mi away · NPDES IA0077305
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2022-09-12
Monitoring stations: 1