Cowley Lake
Hennepin County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Cowley Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
Cowley Lake in Hennepin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 0.8 ft visibility. Phosphorus: 738.6 µg/L. Chlorophyll-a (algae): 343.5 µg/L.
Cowley Lake is a highly nutrient-loaded hypereutrophic lake in Hennepin County, Minnesota. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 80 other monitored lakes in Hennepin County, Cowley Lake ranks #80 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-01. Methodology: how these readings are compared.
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Cowley Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Cowley Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Cowley Lake
These are the measurements Minnesota PCA publishes for Cowley Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 0.8 ft of visibility. Phosphorus 738.6 µg/L. Chlorophyll-a 343.5 µg/L. TSI 89.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 0.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 739µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 344µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 89 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Cowley Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Cowley Lake typically sits around 65°F at the surface in October. Summer average is about 71°F. Usually warmest in Jul (about 72°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (61°F) to its warmest (72°F).
Typical surface water temperature by month, from 57 field readings (2023–2024) via the EPA Water Quality Portal. See the full Cowley Lake water temperature breakdown →
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Cowley Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fish Stocking History — CowleyFish Stocking History · MN DNR LakeFinder
Stays via Stay22
Stays near Cowley Lake
Compare lakeside cabins, hotels, and vacation rentals near Cowley Lake in Hennepin County, Minnesota — 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Cowley Lake are listed below.
Top-rated places to stay near Cowley Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fishing Cowley Lake
Water quality readings over time
2 seasons of samples on record (2023–2024). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
Phosphorus
Improving-80.1 µg/L/yr2 years
Chlorophyll-a
Improving-36 µg/L/yr2 years
EPA Impairment Status
Cowley Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN27-0169-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Cowley Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Met Council - Rogers WrrfRogers · 1.5 mi away · NPDES MN0029629MajorRecent 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.
Nearby Lakes in Hennepin County
Frequently asked questions about Cowley Lake
Where is Cowley Lake?
- Cowley Lake is a lake in Hennepin County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Cowley Lake?
- Cowley Lake in Hennepin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 0.8 ft visibility. Phosphorus: 738.6 µg/L. Chlorophyll-a (algae): 343.5 µg/L.
Is Cowley Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Cowley Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Cowley Lake?
- Cowley Lake typically sits around 65°F at the surface in October, from 57 EPA Water Quality Portal field readings (2023–2024). That is a typical value for the month, not a live reading.
Can I fish at Cowley Lake?
- Public access to Cowley Lake is listed as no on the lake record, so confirm before you make the trip. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Cowley Lake across LakeQuality
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Where this data comes from
64 measurements from 1 monitoring station, 2023–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA64 samples · 2023–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 4500 N C ~ Persufate Method for Total Nitrogen
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)