Three Island Lake
Three Island Lake in Beltrami County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.8 ft visibility. Phosphorus: 17 µg/L. Chlorophyll-a (algae): 4.1 µg/L. Maximum depth: 25 ft. Surface area: 729.49 acres.
- Clarity
- 11.8 ft
- Max depth
- 25 ft
- Area
- 729 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 23
- Open water
- 209 days
Next lake in Beltrami County
Three Island Lake is a 729-acre mesotrophic lake in Beltrami County, Minnesota with a maximum depth of 25 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 17 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available. Compared to the 84 other monitored lakes in Beltrami County, Three Island Lake ranks #29 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 11.8 ft. Phosphorus level: 17 µg/L. Chlorophyll-a: 4.1 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.8 ft | Not graded |
| Phosphorus | 17 µg/L | Good |
| Chlorophyll-a (Algae) | 4.1 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Three Island Lake
Compare lakeside cabins, hotels, and vacation rentals near Three Island Lake in Beltrami 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.
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 25 ft |
| Surface Area | 729 acres |
| Shoreline Length | 10.4 mi |
| Littoral Zone | 87% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Three Island Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2021-08-23 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| CNM | 26.72 | — |
| Yellow Perch | 23.49 | 0.17 lb |
| IOD | 8.22 | — |
| Black Bullhead | 7.12 | 0.61 lb |
| BCS | 7.01 | — |
| Yellow Bass | 5.93 | 0.63 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
Black Bullhead
Yellow Bass
From the 2021-08-23 survey
Three Island Lake is a 729-acre lake located 14 miles northeast of Bemidji in Beltrami County. Three Island is a large, shallow lake basin with lots of aquatic vegetation. The maximum depth is 25 feet; however, much of the lake is less than 9 feet deep. Ice travel is limited during winter months by areas of current…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Three Island Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Three IslandFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Three Island (1761)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — Three IslandFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Three IslandPublic 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 | +0.073 m/yr | 6 |
| Phosphorus | → Stable | -0.06 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.21 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (16 observations).
Estimated open water season: 209 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-23 (2012) | 2013-05-07 (2013) |
| Ice-In | 2003-11-02 (2003) | 2012-11-23 (2012) |
Most recent ice-out: 2019-04-24
EPA Impairment Status
Three Island 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 MN04-0134-00 · Official waterbody report
County Ranking
Ranked #29 of 85 lakes in Beltrami County
Nearby Lakes in Beltrami County
Frequently asked questions about Three Island Lake
What is the water quality grade for Three Island Lake?
- Three Island Lake in Beltrami County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.8 ft visibility. Phosphorus: 17 µg/L. Chlorophyll-a (algae): 4.1 µg/L. Maximum depth: 25 ft. Surface area: 729.49 acres.
Is Three Island Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Three Island Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4.1 µg/L. Always check local health department advisories before swimming.
How deep is Three Island Lake?
- Three Island Lake has a maximum depth of 25 feet. The lake covers 729.49 acres.
What fish are in Three Island Lake?
- Fish species found in Three Island Lake include black crappie, bluegill, bowfin (dogfish), brown bullhead, hybrid sunfish, largemouth bass, northern pike, northern sunfish, pumpkinseed, redhorse, rock bass, shorthead redhorse, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Three Island Lake is located in Beltrami County, Minnesota.
When does Three Island Lake thaw?
- Three Island Lake typically has ice-out around Apr 23. Ice typically forms around Nov 18. The open water season is approximately 209 days.
Explore Three Island Lake across LakeGrade
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Moderate nutrients, good water quality
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Where this data comes from
54 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
MNPCA54 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
Ice data from Minnesota DNR Climate