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LakeQuality

West Okoboji Lake

Dickinson County, IowaView mapDirections

A
Excellent

Clarity, phosphorus, and algae all sit in the cleanest band for this region.

Water temp
49°F
USGS · Sep 7
Clarity
15.7 ft
Secchi · sampled 2024
Level
4.04 ft
USGS · Sep 7 · gage height
Trend
Declining
5 years of samples
  • Mesotrophic
  • Impaired · Pathogens (E. coli, fecal)
  • #1 of 8 in the county
  • Public access

West Okoboji Lake in Dickinson County, Iowa has a water quality grade of A (Excellent). Water clarity: 15.7 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 2.3 µg/L.

Clarity
15.7 ft
Typical in September
71°F
Type
Mesotrophic
Trend
Declining
Public access
Yes
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Free interactive depth-contour map of West Okoboji Lake, reaching a maximum surveyed depth of 135 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.

West Okoboji Lake is a mesotrophic lake in Dickinson County, Iowa. Water quality is graded A 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, West Okoboji Lake ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-10. Grade methodology: LakeQuality methodology.

What West Okoboji Lake is good for

From access and monitoring records, not editorial picks.

  • Clear water15.7 ft of visibility
  • Boat launch1 documented ramp
PDF

West Okoboji Lake Water Quality Report Card (2026)

A printable one-page report card for West Okoboji Lake: grade, clarity, phosphorus, algae, multi-year trend, depth, and fish — with sources.

Swimming Safety

Grade only

Bacteria A · advisory

Based on clarity and algae grades from past sampling — we do not hold a current cyanobacteria reading for this lake. Check your state or county health department before you swim.

Water 49°F now

A
Bacteria swim-safety grade: A
from E. coli testing · 5 samples, 2 seasons

Based on E. coli testing, West Okoboji 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.

Compare the safest swimming lakes near Mankato

Get alerts for West Okoboji Lake

Water Quality Grade: A (Excellent)

Crystal clear, you can see 15.7 ft down. Phosphorus 20 µg/L. Chlorophyll-a 2.3 µg/L. TSI 41. The letter is not a swimming clearance.

MetricValueGrade
Water Clarity (Secchi Depth)15.7 ftNot graded
Phosphorus20 µg/LGood
Chlorophyll-a (Algae)2.3 µg/LGood
Trophic State Index (TSI)41Mesotrophic

Moderate nutrients, good water quality

Current Conditions

49°F
Water Temperature
4.04 ft
Gage Height

USGS snapshot Sep 7, 2026, 3:45 PM from gauge 06604200 (West Okoboji Lake at Lakeside Lab near Milford, IA). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.

West Okoboji Lake water level: the live USGS gauge reading

Water Temperature

West Okoboji Lake typically sits around 71°F at the surface in September. Summer average is about 74°F. Usually warmest in Jul (about 78°F) and coldest in May (about 61°F). These are typical values by month — see Current Conditions above for the latest gauge reading.

Jan
Feb
Mar
Apr
May
61°
Jun
67°
Jul
78°
Aug
76°
Sep
71°
Oct
Nov
Dec

Typical surface water temperature by month, from 101 field readings (20102023) via the EPA Water Quality Portal. See the full West Okoboji Lake water temperature breakdown →

Recreation & Access

1
Boat Landings
Yes
Public Access
  • Okoboji Sailing CenterSemi-private

Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps

Fishing West Okoboji Lake

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.309 m/yr5
Phosphorus Declining+0.8 µg/L/yr4
Chlorophyll-a Declining+0.1 µg/L/yr5
See year-by-year chart →

EPA Impairment Status

West 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

Pathogens (E. coli, fecal)

Source: EPA ATTAINS assessment unit IA 06-LSR-2066 · Official waterbody report · Matched by proximity (2.28 km)

Regulated Pollution Sources Nearby

15 EPA-permitted facilities operate within about 5 miles of West Okoboji Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.

  • Central Water System
    Okoboji · 0.8 mi away · NPDES IA0083879
    Recent violation
  • Whitecap Addition
    Arnolds Park · 0.7 mi away · NPDES IA0052945
  • Quiring Residence Stormwater
    Okoboji · 0.8 mi away · NPDES IA0053623
  • Lakeside Ave. Infrastructure Improvements
    Wahpeton · 0.8 mi away · NPDES IA0053299
  • Sherwood Forest
    Okoboji · 0.8 mi away · NPDES IA0053342
  • Wahpeton Street Improvements Project
    Wahpeton · 0.9 mi away · NPDES IA0053631

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 #1 of 8 lakes in Dickinson County

Nearby Lakes in Dickinson County

Frequently asked questions about West Okoboji Lake

Where is West Okoboji Lake?

West Okoboji Lake is a lake in Dickinson County, Iowa. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.

What is the water quality grade for West Okoboji Lake?

West Okoboji Lake in Dickinson County, Iowa has a water quality grade of A (Excellent). Water clarity: 15.7 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 2.3 µg/L.

Is West Okoboji Lake safe to swim in?

Based on E. coli testing, West Okoboji 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. West Okoboji Lake has a water quality grade of A (Excellent). 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 West Okoboji Lake?

West Okoboji Lake typically sits around 71°F at the surface in September, from 101 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading. A USGS gauge on this lake last read 49°F.

What is the water level at West Okoboji Lake?

The USGS snapshot on this page for West Okoboji Lake is 4.04 ft of gage height, recorded Sep 7, 2026, 3:45 PM at gauge 06604200. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.

Are there boat ramps on West Okoboji Lake?

West Okoboji Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Okoboji Sailing Center. Public access is listed as yes.

Where this data comes from

264 measurements from 5 monitoring stations, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

  • Iowa DNR Surface Water Monitoring Data21IOWA_WQX264 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 (5)

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