Oak Lake
Oak Lake in Pine County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4 ft visibility. Maximum depth: 20 ft. Surface area: 458.74 acres.
- Clarity
- 4 ft
- Typical in August
- 73°F
- Max depth
- 20 ft
- Area
- 459 acres
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 14
Next lake in Pine County
Why Oak Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Oak Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Oak Lake is a 459-acre lake in Pine County, Minnesota with a maximum depth of 20 feet (8-foot average). Overall water quality is improving over recent sampling years. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-08. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Oak Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 4 ft. Trophic State Index: 57.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Oak Lake
Compare lakeside cabins, hotels, and vacation rentals near Oak Lake in Pine 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 Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Oak Lake typically sits around 73°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 74°F) and coldest in May (about 53°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 26 field readings (2011–2025) via the EPA Water Quality Portal. See the full Oak Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Oak Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (42,462 cells/mL) on July 7, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 20 ft |
| Average Depth | 8 ft |
| Surface Area | 459 acres |
| Shoreline Length | 4.8 mi |
| Littoral Zone | 94% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Oak LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Oak Lake
DNR Fisheries Survey Summary
11 surveys on file from MN DNR Fisheries. Most recent: 2023-08-14 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 19.59 | 0.67 lb |
| Yellow Perch | 10.64 | 0.17 lb |
| OTS | 8.92 | 2.28 lb |
| Black Crappie | 8.78 | 0.31 lb |
| Bluegill | 7.98 | 0.23 lb |
| Largemouth Bass | 7.05 | 1.76 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Black Bullhead
Yellow Perch
Black Crappie
Bluegill
From the 2023-08-14 survey
Oak Lake is a 422 acre lake in northern Pine County. A paved public access and a private resort are both located on the south shore of the lake. Water clarity is good despite sporadic algae blooms in August. Oak Lake is managed primarily for Walleye. Walleye fry have been stocked in odd years since 2017. Lake use is…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Oak Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — OakFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Oak (0359)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — OakFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — OakPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.103 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (4 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2006-04-11 (2006) | 2008-04-25 (2008) |
| Ice-In | 2006-11-17 (2006) | 2006-11-17 (2006) |
Most recent ice-out: 2008-04-25
EPA Impairment Status
Oak Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN58-0048-00 · Official waterbody report
Graded lakes near Oak Lake
Oak Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Pine County
Frequently asked questions about Oak Lake
What is the water quality grade for Oak Lake?
- Oak Lake in Pine County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4 ft visibility. Maximum depth: 20 ft. Surface area: 458.74 acres.
Is Oak Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Oak Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of Oak Lake?
- Oak Lake typically sits around 73°F at the surface in August, from 26 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Oak Lake?
- Oak Lake has a maximum depth of 20 feet and an average depth of 8 feet. The lake covers 458.74 acres.
What fish are in Oak Lake?
- Fish species found in Oak Lake include black bullhead, black crappie, bluegill, brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow bullhead, yellow perch. Oak Lake is located in Pine County, Minnesota.
When does Oak Lake thaw?
- Oak Lake typically has ice-out around Apr 14.
Does Oak Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Oak Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (42,462 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Oak Lake?
- Oak Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Oak Lake. Public access is listed as yes.
Explore Oak Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
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Fish species and best lakes in Pine County
Species activity outlook by water temperature and season
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Where this data comes from
33 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA33 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate