Long Lake
Long Lake in Beltrami County, Minnesota has a water quality grade of A (Excellent). Water clarity: 20 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 1.8 µg/L. Maximum depth: 87 ft. Surface area: 411.95 acres.
- Clarity
- 20 ft
- Typical in August
- 72°F
- Max depth
- 87 ft
- Area
- 412 acres
- Type
- Oligotrophic
- Trend
- ↓ Declining
- Public access
- No
- Ice-out
- Apr 22
- Open water
- 217 days
Next lake in Beltrami County
Long Lake is a 412-acre cold, clear oligotrophic lake in Beltrami County, Minnesota with a maximum depth of 87 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 11 documented fish species including black crappie, bluegill, and brown bullhead. No public access — the lake is private or restricted. Compared to the 84 other monitored lakes in Beltrami County, Long Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-25. 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)
Crystal clear, you can see 20 ft down. Phosphorus level: 7 µg/L. Chlorophyll-a: 1.8 µg/L. Trophic State Index: 34.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 20 ft | Not graded |
| Phosphorus | 7 µg/L | Good |
| Chlorophyll-a (Algae) | 1.8 µg/L | Good |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long 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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Water Temperature
Long Lake typically sits around 72°F at the surface in August. Summer average is about 73°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 38 field readings (2016–2025) via the EPA Water Quality Portal.
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Long Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was low (13,677 cells/mL) on May 9, 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 | 87 ft |
| Surface Area | 412 acres |
| Shoreline Length | 7.7 mi |
| Littoral Zone | 44% |
| Public Access | No |
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 Long Lake
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 1993-06-14 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 51.06 | 0.09 lb |
| Pumpkinseed | 4.99 | 0.23 lb |
| Northern Pike | 4.96 | 2.79 lb |
| Rock Bass | 4.31 | 0.21 lb |
| Walleye | 2.73 | 2.17 lb |
| White Sucker | 2.53 | 2.07 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.
Bluegill
Pumpkinseed
Northern Pike
Rock Bass
From the 1993-06-14 survey
The fish community of Long Lake is in good shape and near expectations of a lake of relatively low exploitation. Northern Pike were found in good numbers and generally larger than many area lakes. The average length of pike was more than 25 inches. No small pike were captured so there may be some concern if…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Long Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — LongFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.071 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.44 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +0.07 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (26 observations).
Estimated open water season: 217 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2017-04-08 (2017) | 2022-05-07 (2022) |
| Ice-In | 2014-04-12 (2014) | 2015-12-14 (2015) |
Most recent ice-out: 2024-04-23
EPA Impairment Status
Long Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN04-0111-00 · Official waterbody report · Matched by proximity (2.77 km)
County Ranking
Ranked #5 of 85 lakes in Beltrami County
Nearby Lakes in Beltrami County
Frequently asked questions about Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Beltrami County, Minnesota has a water quality grade of A (Excellent). Water clarity: 20 ft visibility. Phosphorus: 7 µg/L. Chlorophyll-a (algae): 1.8 µg/L. Maximum depth: 87 ft. Surface area: 411.95 acres.
Is Long Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Long Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 1.8 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Long Lake?
- Long Lake typically sits around 72°F at the surface in August, from 38 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is Long Lake?
- Long Lake has a maximum depth of 87 feet. The lake covers 411.95 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include black crappie, bluegill, brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, walleye, white sucker, yellow perch. Long Lake is located in Beltrami County, Minnesota.
When does Long Lake thaw?
- Long Lake typically has ice-out around Apr 22. Ice typically forms around Nov 25. The open water season is approximately 217 days.
Does Long Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Long Lake (clouds, ice, or an off-season gap). The most recent reading was low (13,677 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Explore Long Lake across LakeGrade
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Where this data comes from
182 measurements from 3 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA182 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 (3)
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