Otter Creek Lake is a 60-acre productive, nutrient-rich eutrophic lake in Tama County, Iowa. Water quality is graded D based on 2 sampling years through 2021. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 2 other monitored lakes in Tama County, Otter Creek Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2021-08-04. Grade methodology: LakeGrade methodology.
Watch Otter Creek Lake water quality
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 1.3 ft of visibility. Chlorophyll-a: 24 µg/L. Trophic State Index: 67.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 24 µg/L | D |
| Trophic State Index (TSI) | 67 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 60 acres |
| Public Access | Yes |
Where to stay near Otter Creek Lake
Compare lakeside cabins, hotels, and vacation rentals near Otter Creek Lake in Tama County, Iowa — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Fishing Otter Creek Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.44 m/yr | 2 |
| Chlorophyll-a | ↑ Improving | -22.6 µg/L/yr | 2 |
Water Temperature
Otter Creek Lake averages about 76°F at the surface in summer, usually warmest in Aug (about 78°F) and coldest in May (about 68°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 63 field readings (2010–2020) via the EPA Water Quality Portal. See the full Otter Creek Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Otter Creek Lake, reaching a maximum surveyed depth of 22 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #1 of 3 lakes in Tama County
Cleaner Lakes Within 30 Miles
Otter Creek Lake holds Grade D. 2 nearby lakes hold higher grades.
- BSand LakeMarshall County · 17.8 mi · Two grade letters higher (D → B)
- CGreen Castle LakeMarshall County · 19.2 mi · Higher grade (D → C)
Nearby Lakes in Tama County
Explore Otter Creek Lake across LakeGrade
More Iowa Lake Rankings
Other Grade D Lakes in Iowa
Eutrophic Lakes in Iowa
More records, surveys & data sources
Reservoir Info (USACE NID)
Otter Creek Lake is a man-made reservoir impounded by the Otter Creek Lake Dam (completed 1968), built primarily for recreation on the OTTER CREEK; earth-type dam, 45 ft tall and 935 ft long.
- Surface area
- 60 ac
- Normal storage
- 680 ac-ft
- Max storage
- 1,290 ac-ft
- Drainage area
- 1.74 sq mi
- Hazard class
- Significant
- Owner
- Tama County Conservation Board
Source: USACE National Inventory of Dams, NID ID IA01032 · Operator website
EPA Impairment Status
Otter Creek 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-IOW-720 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Otter Creek Lake under Clean Water Act (NPDES) discharge permits.
- Toledo, City Of WtpToledo · 4.6 mi away · NPDES IA0083526
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)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2021-08-04
Monitoring stations: 1