Little Sioux Park Lake is a mesotrophic lake in Woodbury County, Iowa. Water quality is graded C based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. Compared to the 2 other monitored lakes in Woodbury County, Little Sioux Park Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-03. Grade methodology: LakeGrade methodology.
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Swimming Safety
Based on E. coli testing, Little Sioux Park Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 5 samples across 2 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Iowa’s current beach and health-department advisories before swimming.
Water Quality Grade: C, Fair
Murky, only visible to about 5.7 ft. Chlorophyll-a: 5.7 µg/L. Trophic State Index: 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.7 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 5.7 µg/L | B |
| Trophic State Index (TSI) | 50 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Little Sioux Park Lake
Compare lakeside cabins, hotels, and vacation rentals near Little Sioux Park Lake in Woodbury 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.
Top-rated places to stay near Little Sioux Park Lake
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Fishing Little Sioux Park Lake
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.468 m/yr | 4 |
| Chlorophyll-a | ↓ Declining | +0.25 µg/L/yr | 4 |
Water Temperature
Little Sioux Park Lake averages about 79°F at the surface in summer, usually warmest in Jun (about 79°F) and coldest in May (about 65°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 26 field readings (2010–2023) via the EPA Water Quality Portal. See the full Little Sioux Park Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Little Sioux Park Lake, reaching a maximum surveyed depth of 28 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #1 of 3 lakes in Woodbury County
Nearby Lakes in Woodbury County
Explore Little Sioux Park Lake across LakeGrade
More Iowa Lake Rankings
Other Grade C Lakes in Iowa
Mesotrophic Lakes in Iowa
More records, surveys & data sources
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Little Sioux Park Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Correctionville City Of StpCorrectionville · 1.9 mi away · NPDES IA0023531Recent violation
- Iowa Dot Maintenance Garage-CorrectionvilleCorrectionville · 2.8 mi away · NPDES IA0076325
- Pithan Feedlots, Inc.Anthon · 4.4 mi away · NPDES IA0080683
- Anthon City Of StpAnthon · 4.5 mi away · NPDES IA0042854
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-03
Monitoring stations: 1