Oak Leaf Lake
Nicollet County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Oak Leaf Lake. Here is what has been measured.
- Eutrophic
- 35 ft max depth
- Public access
- Limited data
Oak Leaf Lake in Nicollet County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.9 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 4.9 µg/L.
Oak Leaf Lake is a productive, nutrient-rich eutrophic lake in Nicollet County, Minnesota with an estimated average depth of about 35 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 1 other monitored lakes in Nicollet County, Oak Leaf Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. Methodology: how these readings are compared.
What Oak Leaf Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyLimited data
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. Check local advisories before you swim.
Whether Oak Leaf 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 Oak Leaf Lake
These are the measurements Minnesota PCA publishes for Oak Leaf Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.9 ft. Phosphorus 30 µg/L. Chlorophyll-a 4.9 µg/L. TSI 52.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 30µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 4.9µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 52 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Oak Leaf Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Oak Leaf Lake typically sits around 64°F at the surface in September. Summer average is about 71°F. Usually warmest in Aug (about 75°F) and coldest in Sep (about 64°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (64°F) to its warmest (75°F).
Typical surface water temperature by month, from 13 field readings (2024–2025) via the EPA Water Quality Portal. See the full Oak Leaf Lake water temperature breakdown →
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Oak Leaf Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Public Water Access Sites — Oak LeafPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
~35 ft est.
Public access
Yes
Listed by Minnesota PCA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Oak Leaf Lake.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Surface area
104 acres
HydroLAKES / HydroSHEDS
Shoreline
2.4 mi
HydroLAKES / HydroSHEDS
Elevation
971 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
- Oak Leaf LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Oak Leaf Lake
Compare lakeside cabins, hotels, and vacation rentals near Oak Leaf Lake in Nicollet 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.
Top-rated places to stay near Oak Leaf Lake
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Follow Oak Leaf Lake’s readings
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Fishing Oak Leaf Lake
Water quality readings over time
2 seasons of samples on record (2024–2025). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
Phosphorus
Worsening+3 µg/L/yr2 years
Chlorophyll-a
Improving-3.5 µg/L/yr2 years
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Oak Leaf Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Iron Oak Sand Llc - KasotaKasota · 2.8 mi away · NPDES MN0053082Recent 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 Nicollet County
Frequently asked questions about Oak Leaf Lake
Where is Oak Leaf Lake?
- Oak Leaf Lake is a lake in Nicollet County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Oak Leaf Lake?
- Oak Leaf Lake in Nicollet County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.9 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 4.9 µg/L.
Is Oak Leaf Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Oak Leaf Lake?
- Oak Leaf Lake typically sits around 64°F at the surface in September, from 13 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Oak Leaf Lake?
- No published bathymetric survey covers Oak Leaf Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 35 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 Oak Leaf Lake?
- Oak Leaf Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Oak Leaf Lake. Public access is listed as yes.
Can I fish at Oak Leaf Lake?
- Oak Leaf Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. 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 Oak Leaf Lake across LakeQuality
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Species activity outlook by water temperature and season
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Where this data comes from
21 measurements from 1 monitoring station, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA21 samples · 2024–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory