Big Spirit Lake is a productive, nutrient-rich eutrophic lake in Dickinson County, Iowa. Water quality is graded C based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 7 public boat landings. Compared to the 7 other monitored lakes in Dickinson County, Big Spirit Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-09. Grade methodology: LakeGrade methodology.
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Swimming Safety
Based on E. coli testing, Big Spirit 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 5.5 ft. Chlorophyll-a: 16.3 µg/L. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.5 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 16.3 µg/L | C |
| Trophic State Index (TSI) | 55 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Big Spirit Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Spirit Lake in Dickinson 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 Big Spirit Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.185 m/yr | 5 |
| Chlorophyll-a | ↓ Declining | +4.38 µg/L/yr | 5 |
Recreation & Access
Water Temperature
Big Spirit Lake averages about 73°F at the surface in summer, usually warmest in Jul (about 79°F) and coldest in May (about 67°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 27 field readings (2010–2023) via the EPA Water Quality Portal. See the full Big Spirit Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Big Spirit 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 #3 of 8 lakes in Dickinson County
Cleaner Lakes Within 30 Miles
Big Spirit Lake holds Grade C. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Dickinson County
Explore Big Spirit Lake across LakeGrade
Species activity outlook by water temperature and season
Top lakes and where to stay in the Iowa Great Lakes area
Where to stay at Iowa's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
Iowa's cleanest and most-polluted lakes, ranked
More Iowa Lake Rankings
Other Grade C Lakes in Iowa
Eutrophic 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
1 EPA-permitted facility operate within about 5 miles of Big Spirit Lake under Clean Water Act (NPDES) discharge permits.
- Big Spirit Lake Aquatic Vegetation ManagementSpirit Lake · 0.9 mi away · NPDES IA0053585
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
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2024-09-09
Monitoring stations: 1