Long Lake
Long Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 12.3 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 4.4 µg/L. Maximum depth: 128 ft. Surface area: 1289.21 acres.
- Clarity
- 12.3 ft
- Max depth
- 128 ft
- Area
- 1,289 acres
- Type
- Mesotrophic
- Public access
- Yes
- Ice-out
- Apr 15
Next lake in Otter Tail County
Free interactive depth-contour map of Long Lake, reaching a maximum surveyed depth of 120 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Long Lake is a 1,289-acre mesotrophic lake in Otter Tail County, Minnesota with a maximum depth of 128 feet. Water quality is graded A based on 2 sampling years through 2025. The lake supports 16 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available with 1 public boat landing. Compared to the 65 other monitored lakes in Otter Tail County, Long Lake ranks #4 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 12.3 ft. Phosphorus level: 20 µg/L. Chlorophyll-a: 4.4 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12.3 ft | Not graded |
| Phosphorus | 20 µg/L | Good |
| Chlorophyll-a (Algae) | 4.4 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long Lake in Otter Tail 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 | 128 ft |
| Surface Area | 1,289 acres |
| Shoreline Length | 12.6 mi |
| Littoral Zone | 41% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Long LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Long 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
12 surveys on file from MN DNR Fisheries. Most recent: 2024-06-17 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 34.24 | 0.14 lb |
| Bluntnose Minnow | 24.58 | — |
| BNS | 17.20 | — |
| Largemouth Bass | 10.27 | 0.88 lb |
| GOS | 9.26 | 0.04 lb |
| BKF | 8.07 | — |
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
Largemouth Bass
GOS
From the 2024-06-17 survey
Long Lake is a 1,273-acre lake located in north-central Otter Tail County. The southwest shoreline of the lake abuts the city of Vergas, MN. Long Lake is composed of two distinct basins. The west basin is characteristic of an oligotrophic lake (i.e., deep and unfertile) while the east basin is characteristic of a…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Long Lake. 3 reports 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
- —Fish Stocking History — LongFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — LongPublic Water Access Sites · MN DNR LakeFinder
Ice Season
Historical ice data from Minnesota DNR (5 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2015-04-13 (2015) | 2013-05-11 (2013) |
| Ice-In | 2002-11-25 (2002) | 2003-12-10 (2003) |
Most recent ice-out: 2015-04-13
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 MN56-0388-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Long Lake under Clean Water Act (NPDES) discharge permits.
- Schlauderaff EnterprisesFrazee · 1.5 mi away · NPDES MN0071684
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.
County Ranking
Ranked #4 of 66 lakes in Otter Tail County
Nearby Lakes in Otter Tail County
Frequently asked questions about Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 12.3 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 4.4 µg/L. Maximum depth: 128 ft. Surface area: 1289.21 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 4.4 µg/L. Always check local health department advisories before swimming.
How deep is Long Lake?
- Long Lake has a maximum depth of 128 feet. The lake covers 1289.21 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Long Lake is located in Otter Tail County, Minnesota.
When does Long Lake thaw?
- Long Lake typically has ice-out around Apr 15.
Are there boat ramps on Long Lake?
- Long Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Long Lake. Public access is listed as yes.
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Where this data comes from
186 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
MNPCA186 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
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
Ice data from Minnesota DNR Climate