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LakeQuality

Okamanpeedan Lake

F
Grade F — Algae-prone
Algae-prone · #2 of 2 lakes in the county · 1 ft clear · Hypereutrophic
Limited DataHypereutrophic

Okamanpeedan Lake in Emmet County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 1 ft visibility. Phosphorus: 155 µg/L. Chlorophyll-a (algae): 63.2 µg/L.

Clarity
1 ft
Typical in August
77°F
Max depth
~54 ft est.
Type
Hypereutrophic
Public access
Yes

Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Okamanpeedan Lake

Next lake in Emmet County

FIngham Lake1.4 ft clear · Emmet CountyView →
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Okamanpeedan Lake is a highly nutrient-loaded hypereutrophic lake in Emmet County, Iowa with an estimated average depth of about 54 feet. Water quality is graded F based on 2 sampling years through 2025. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 1 other monitored lakes in Emmet County, Okamanpeedan Lake ranks #2 for water quality.

Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2025-09-16. Grade methodology: LakeGrade methodology.

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Swimming Safety

Grade only

Limited data

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.

Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom

Compare the safest swimming lakes near Mankato

Get alerts for Okamanpeedan Lake

Water Quality Grade: F (Algae-prone)

Very murky, less than 1 ft of visibility. Phosphorus level: 155 µg/L. Chlorophyll-a: 63.2 µg/L. Trophic State Index: 75.

MetricValueGrade
Water Clarity (Secchi Depth)1 ftNot graded
Phosphorus155 µg/LPoor
Chlorophyll-a (Algae)63.2 µg/LPoor
Trophic State Index (TSI)75Hypereutrophic

Very high nutrients, dense algae, poor clarity

Where to stay near Okamanpeedan Lake

Compare lakeside cabins, hotels, and vacation rentals near Okamanpeedan Lake in Emmet 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 Okamanpeedan Lake are listed below.

Top-rated places to stay near Okamanpeedan Lake

Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.

Planning a trip? Cabins and lodging at Okamanpeedan Lake · more Iowa lake trips

Water Temperature

Okamanpeedan Lake typically sits around 77°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 77°F) and coldest in May (about 55°F). These are typical values by month — not a live reading.

Jan
Feb
Mar
Apr
May
55°
Jun
67°
Jul
77°
Aug
77°
Sep
63°
Oct
Nov
Dec

Typical surface water temperature by month, from 13 field readings (20142014) via the EPA Water Quality Portal. See the full Okamanpeedan Lake water temperature breakdown →

Lake Details

CharacteristicValue
Maximum Depth~54 ft est.
Average Depth~11 ft est.
Public AccessYes

Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Okamanpeedan Lake.

Lake Size & Watershed

Watershed (drainage) area
178 sq mi
Surface area
2,226 acres
Shoreline
12.8 mi
Elevation
1,220 ft

Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.

Recreation & Access

1
Boat Landings
Yes
Public Access
  • Tuttle Lake Wetland ComplexPublic

Fishing Okamanpeedan Lake

EPA Impairment Status

Okamanpeedan Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Algal growthTurbidity

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit IA 04-EDM-975 · Official waterbody report · Matched by proximity (0.31 km)

Regulated Pollution Sources Nearby

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

  • Dolliver, City Of Stp
    Dolliver · 2.4 mi away · NPDES IA0082147
    Recent 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.

County Ranking

Ranked #2 of 2 lakes in Emmet County

Nearby Lakes in Emmet County

Frequently asked questions about Okamanpeedan Lake

What is the water quality grade for Okamanpeedan Lake?

Okamanpeedan Lake in Emmet County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 1 ft visibility. Phosphorus: 155 µg/L. Chlorophyll-a (algae): 63.2 µg/L.

Is Okamanpeedan Lake safe to swim in?

Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Okamanpeedan Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 63.2 µg/L. Always check local health department advisories before swimming.

What is the water temperature of Okamanpeedan Lake?

Okamanpeedan Lake typically sits around 77°F at the surface in August, from 13 EPA Water Quality Portal field readings (2014–2014). That is a typical value for the month, not a live reading.

How deep is Okamanpeedan Lake?

No published bathymetric survey covers Okamanpeedan Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 54 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.

Are there boat ramps on Okamanpeedan Lake?

Okamanpeedan Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Tuttle Lake Wetland Complex. Public access is listed as yes.

Where this data comes from

15 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

  • Minnesota Pollution Control Agency - Ambient Surface WaterMNPCA15 samples · 2025

Analytical methods

  • Field measurement/observation, generic method
  • Phosphorus by Colorimetry
  • 10200 H ~ Chlorophyll a-b-c Determination
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)

Lake size & watershed from HydroLAKES (HydroSHEDS)

Named boat-access points from the USGS National Boat Ramps inventory