One Pine Lake
One Pine Lake in St. Louis County, Minnesota has a water quality grade of C (Fair). Water clarity: 4.5 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 8.6 µg/L. Maximum depth: 13 ft. Surface area: 353.54 acres.
- Clarity
- 4.5 ft
- Typical in August
- 74°F
- Max depth
- 13 ft
- Area
- 354 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 29
Next lake in St. Louis County
One Pine Lake is a 354-acre productive, nutrient-rich eutrophic lake in St. Louis County, Minnesota with a maximum depth of 13 feet. Water quality is graded C based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 13 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 2 public boat landings. Compared to the 67 other monitored lakes in St. Louis County, One Pine Lake ranks #44 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-15. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited 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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Murky, only visible to about 4.5 ft. Phosphorus level: 27 µg/L. Chlorophyll-a: 8.6 µg/L. Trophic State Index: 53.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.5 ft | Not graded |
| Phosphorus | 27 µg/L | Fair |
| Chlorophyll-a (Algae) | 8.6 µg/L | Fair |
| Trophic State Index (TSI) | 53 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near One Pine Lake
Compare lakeside cabins, hotels, and vacation rentals near One Pine Lake in St. Louis 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 One Pine Lake
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Water Temperature
One Pine Lake typically sits around 74°F at the surface in August. Summer average is about 71°F. Usually warmest in Aug (about 74°F) and coldest in Oct (about 51°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 40 field readings (2023–2025) via the EPA Water Quality Portal. See the full One Pine Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for One Pine Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (216,770 cells/mL) on May 30, 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 | 13 ft |
| Surface Area | 354 acres |
| Shoreline Length | 4.6 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- One Pine LakePublic
- Johnson LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing One Pine Lake
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2023-07-10 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 4.34 | 0.16 lb |
| Bluegill | 3.79 | 0.45 lb |
| White Sucker | 3.51 | 2.51 lb |
| Walleye | 3.48 | 1.24 lb |
| Northern Pike | 2.47 | 2.06 lb |
| Black Crappie | 2.25 | 0.44 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.
Yellow Perch
Bluegill
White Sucker
Walleye
From the 2023-07-10 survey
One Pine Lake is a 354-acre lake located seven miles south of Ely. There is a public access with a gravel boat ramp located on the west side of the lake off CSAH 21. One Pine Lake is relatively shallow, with a maximum depth of just 13 feet. Lake bottom substrates along the shoreline are mostly rubble, boulder, and…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for One Pine Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — One PineFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — One Pine (1883)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — One PinePublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.056 m/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (5 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2021-04-08 (2021) | 2022-05-08 (2022) |
| Ice-In | 2022-11-18 (2022) | 2020-11-20 (2020) |
Most recent ice-out: 2022-05-08
EPA Impairment Status
One Pine Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN69-0061-00 · Official waterbody report
County Ranking
Ranked #44 of 68 lakes in St. Louis County
Nearby Lakes With Higher Grades
One Pine Lake holds Grade C. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in St. Louis County
Frequently asked questions about One Pine Lake
What is the water quality grade for One Pine Lake?
- One Pine Lake in St. Louis County, Minnesota has a water quality grade of C (Fair). Water clarity: 4.5 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 8.6 µg/L. Maximum depth: 13 ft. Surface area: 353.54 acres.
Is One Pine Lake safe to swim in?
- Generally safe for swimming, moderate water quality. One Pine Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 8.6 µg/L. Always check local health department advisories before swimming.
What is the water temperature of One Pine Lake?
- One Pine Lake typically sits around 74°F at the surface in August, from 40 EPA Water Quality Portal field readings (2023–2025). That is a typical value for the month, not a live reading.
How deep is One Pine Lake?
- One Pine Lake has a maximum depth of 13 feet. The lake covers 353.54 acres.
What fish are in One Pine Lake?
- Fish species found in One Pine Lake include black bullhead, black crappie, bluegill, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, smallmouth bass, walleye, white sucker, yellow bullhead, yellow perch. One Pine Lake is located in St. Louis County, Minnesota.
When does One Pine Lake thaw?
- One Pine Lake typically has ice-out around Apr 29.
Does One Pine Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for One Pine Lake (clouds, ice, or an off-season gap). The most recent reading was high (216,770 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on One Pine Lake?
- One Pine Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include One Pine Lake, Johnson Lake. Public access is listed as yes.
Explore One Pine Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
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Fish species and best lakes in St. Louis County
Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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More Minnesota Lake Rankings
State Parks Near One Pine Lake
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Where this data comes from
49 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
MNPCA49 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent 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
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