East Okoboji Lake
Dickinson County, IowaView mapDirections
Nutrients and algae run above the regional average.
- Eutrophic
- Impaired · Mercury
- #6 of 8 in the county
- Public access
East Okoboji Lake in Dickinson County, Iowa has a water quality grade of D (Nutrient-rich). Water clarity: 3.9 ft visibility. Phosphorus: 56 µg/L. Chlorophyll-a (algae): 25.3 µg/L.
- Clarity
- 3.9 ft
- Typical in September
- 72°F
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near East Okoboji Lake
Compare lakeside cabins, hotels, and vacation rentals near East Okoboji 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around East Okoboji Lake are listed below.
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Free interactive depth-contour map of East Okoboji Lake, reaching a maximum surveyed depth of 20 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
East Okoboji Lake is a productive, nutrient-rich eutrophic lake in Dickinson County, Iowa. Water quality is graded D 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 4 public boat landings. Compared to the 7 other monitored lakes in Dickinson County, East Okoboji Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-10. Grade methodology: LakeQuality methodology.
What East Okoboji Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch4 documented ramps
Swimming Safety
Grade onlyAlgae risk
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.
The D is nutrients and algae, not a swimming clearance. East Okoboji Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 3.9 ft. Phosphorus 56 µg/L. Chlorophyll-a 25.3 µg/L. TSI 61. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.9 ft | Not graded |
| Phosphorus | 56 µg/L | Fair |
| Chlorophyll-a (Algae) | 25.3 µg/L | Poor |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
East Okoboji Lake typically sits around 72°F at the surface in September. Summer average is about 75°F. Usually warmest in Jul (about 80°F) and coldest in Jun (about 69°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 East Okoboji Lake water temperature breakdown →
Recreation & Access
- Spring Run ComplexPublic
- Hattie Elston State ParkPublic
- Martin DrivePublic
- Parks MarinaSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing East Okoboji Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.099 m/yr | 5 |
| Phosphorus | ↓ Declining | +3.8 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -3.05 µg/L/yr | 5 |
EPA Impairment Status
East Okoboji Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit IA 06-LSR-1652 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of East Okoboji Lake under Clean Water Act (NPDES) discharge permits.
- Iowa Dot Hwy 71 ConstructionOkoboji · 0.7 mi away · NPDES IA0053380
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 #6 of 8 lakes in Dickinson County
Nearby Lakes With Higher Grades
East Okoboji Lake holds Grade D. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Dickinson County
Frequently asked questions about East Okoboji Lake
Where is East Okoboji Lake?
- East Okoboji Lake is a lake in Dickinson County, Iowa. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for East Okoboji Lake?
- East Okoboji Lake in Dickinson County, Iowa has a water quality grade of D (Nutrient-rich). Water clarity: 3.9 ft visibility. Phosphorus: 56 µg/L. Chlorophyll-a (algae): 25.3 µg/L.
Is East Okoboji Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. East Okoboji Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
What is the water temperature of East Okoboji Lake?
- East Okoboji Lake typically sits around 72°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 East Okoboji Lake?
- East Okoboji Lake has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Spring Run Complex, Hattie Elston State Park, Martin Drive, Parks Marina. Public access is listed as yes.
Explore East Okoboji 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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Other Grade D Lakes in Iowa
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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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory