Littlefield Lake is a 69-acre highly nutrient-loaded hypereutrophic lake in Audubon County, Iowa. Water quality is graded F based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-29. Grade methodology: LakeGrade methodology.
Watch Littlefield Lake water quality
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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 0.9 ft of visibility. Chlorophyll-a: 103.1 µg/L. Trophic State Index: 77.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.9 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 103.1 µg/L | F |
| Trophic State Index (TSI) | 77 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 69 acres |
Where to stay near Littlefield Lake
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Fishing Littlefield Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.027 m/yr | 5 |
| Chlorophyll-a | ↓ Declining | +30.75 µg/L/yr | 5 |
Water Temperature
Littlefield Lake averages about 78°F at the surface in summer, usually warmest in Jul (about 81°F) and coldest in Sep (about 70°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full Littlefield Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Littlefield Lake, reaching a maximum surveyed depth of 14 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #1 of 1 lakes in Audubon County
Cleaner Lakes Within 30 Miles
Littlefield Lake holds Grade F. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Audubon County
Explore Littlefield Lake across LakeGrade
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More records, surveys & data sources
Reservoir Info (USACE NID)
Littlefield Lake is a man-made reservoir impounded by the Littlefield Lake Dam (completed 1977), built primarily for flood risk reduction on the TR-TROUBLESOME CREEK; earth-type dam, 45 ft tall and 1,205 ft long.
- Surface area
- 69 ac
- Normal storage
- 561 ac-ft
- Max storage
- 2,278 ac-ft
- Drainage area
- 3.95 sq mi
- Hazard class
- High
- Owner
- Audubon County Conservation Board
All listed purposes: Flood Risk Reduction;Recreation.
Source: USACE National Inventory of Dams, NID ID IA01691 · Operator website
EPA Impairment Status
Littlefield 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 05-NSH-1439 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-29
Monitoring stations: 1