Blue Pit Lake is a mesotrophic lake in Cerro Gordo County, Iowa. Water quality is graded A based on 2 sampling years through 2022. Overall water quality is improving over recent sampling years. Compared to the 3 other monitored lakes in Cerro Gordo County, Blue Pit Lake ranks #1 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
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 17.1 ft down. Chlorophyll-a: 4 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 17.1 ft | A |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 4 µg/L | A |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Blue Pit Lake
Compare lakeside cabins, hotels, and vacation rentals near Blue Pit Lake in Cerro Gordo 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 Blue Pit Lake
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.6 m/yr | 3 |
| Chlorophyll-a | ↑ Improving | -15.45 µg/L/yr | 3 |
Water Temperature
Blue Pit Lake averages about 76°F at the surface in summer, usually warmest in Jul (about 80°F) and coldest in Sep (about 68°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 Blue Pit Lake water temperature breakdown →
Location
County Ranking
Ranked #1 of 4 lakes in Cerro Gordo County
Nearby Lakes in Cerro Gordo County
Explore Blue Pit Lake across LakeGrade
More Iowa Lake Rankings
Other Grade A Lakes in Iowa
Mesotrophic Lakes in Iowa
More records, surveys & data sources
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Blue Pit Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Heidelberg Materials Us Cement Llc (Remediation Site)Mason City · 2.5 mi away · NPDES IA0072907Recent violation
- Heidelberg Materials Us Cement LlcMason City · 2.5 mi away · NPDES IA0001945Recent violation
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)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2022-09-12
Monitoring stations: 1