Big Spirit Lake
Dickinson County, IowaView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- #4 of 8 in the county
- Public access
Big Spirit Lake in Dickinson County, Iowa has a water quality grade of C (Fair). Water clarity: 5.5 ft visibility. Phosphorus: 55 µg/L. Chlorophyll-a (algae): 16.3 µg/L.
- Clarity
- 5.5 ft
- Typical in September
- 71°F
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
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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.
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 1 public boat landing. Compared to the 7 other monitored lakes in Dickinson County, Big Spirit Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-09. Grade methodology: LakeQuality methodology.
What Big Spirit Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Grade onlyBacteria A
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
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. Phosphorus 55 µg/L. Chlorophyll-a 16.3 µg/L. TSI 58. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.5 ft | Not graded |
| Phosphorus | 55 µg/L | Fair |
| Chlorophyll-a (Algae) | 16.3 µg/L | Fair |
| Trophic State Index (TSI) | 58 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Big Spirit Lake typically sits around 71°F at the surface in September. Summer average is about 73°F. 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 →
Recreation & Access
- Hales SloughPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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 |
| Phosphorus | ↓ Declining | +8.45 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +4.38 µg/L/yr | 5 |
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.
County Ranking
Ranked #4 of 8 lakes in Dickinson County
Nearby Lakes in Dickinson County
Frequently asked questions about Big Spirit Lake
Where is Big Spirit Lake?
- Big Spirit Lake is a lake in Dickinson County, Iowa. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Big Spirit Lake?
- Big Spirit Lake in Dickinson County, Iowa has a water quality grade of C (Fair). Water clarity: 5.5 ft visibility. Phosphorus: 55 µg/L. Chlorophyll-a (algae): 16.3 µg/L.
Is Big Spirit Lake safe to swim in?
- 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. That works out to a bacteria swim-safety grade of A — a historical summary of past testing, not a current reading. Big Spirit Lake has a water quality grade of C (Fair). Bacteria levels can spike quickly after heavy rain, so always check Iowa's current beach and health-department advisories before you swim.
What is the water temperature of Big Spirit Lake?
- Big Spirit Lake typically sits around 71°F at the surface in September, from 27 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Are there boat ramps on Big Spirit Lake?
- Big Spirit Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Hales Slough. Public access is listed as yes.
Explore Big Spirit Lake across LakeQuality
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
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More Iowa Lake Rankings
Other Grade C Lakes in Iowa
Eutrophic Lakes in Iowa
Where this data comes from
57 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX57 samples · 2020–2024
Analytical methods
- Unknown
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- In-Vitro Determination of Chlorophyll
- ISU modification of APHA 2130-B
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory