Otter Tail Lake
Otter Tail Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 12.1 ft visibility. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 5.5 µg/L. Maximum depth: 120 ft. Surface area: 14078.61 acres.
- Clarity
- 12.1 ft
- Max depth
- 120 ft
- Area
- 14,079 acres
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- Yes
- Ice-out
- Apr 16
- Open water
- 227 days
Next lake in Otter Tail County
Free interactive depth-contour map of Otter Tail Lake, reaching a maximum surveyed depth of 120 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Otter Tail Lake is a 14,079-acre mesotrophic lake in Otter Tail County, Minnesota with a maximum depth of 120 feet. Water quality is graded A based on 2 sampling years through 2025. Water clarity is declining over recent sampling years. The lake supports 17 documented fish species including black bullhead, black crappie, and bluegill. Public access is available. Compared to the 65 other monitored lakes in Otter Tail County, Otter Tail Lake ranks #36 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 12.1 ft. Phosphorus level: 16 µg/L. Chlorophyll-a: 5.5 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12.1 ft | Not graded |
| Phosphorus | 16 µg/L | Good |
| Chlorophyll-a (Algae) | 5.5 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Otter Tail Lake
Compare lakeside cabins, hotels, and vacation rentals near Otter Tail 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 | 120 ft |
| Surface Area | 14,079 acres |
| Shoreline Length | 23.7 mi |
| Littoral Zone | 46% |
| 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 Otter Tail 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: 2021-09-07 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 58.77 | 0.14 lb |
| Walleye | 12.67 | 0.92 lb |
| Tullibee (Cisco) | 3.56 | 0.48 lb |
| Northern Pike | 3.14 | 3.01 lb |
| LKS | 2.93 | 6.6 lb |
| White Sucker | 2.83 | 2.1 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
Walleye
Tullibee (Cisco)
Northern Pike
From the 2021-09-07 survey
Otter Tail Lake is a 13,725 acre mesotrophic (moderately fertile) lake located in central Otter Tail County. The city of Ottertail, MN abuts the east shoreline of the lake. Otter Tail Lake is part of the Otter Tail River chain of lakes. Rush, Big Pine, and Little Pine Lakes are located upstream, while Deer, East Lost,…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Otter Tail Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Otter TailFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — Otter TailFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Otter TailPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.321 m/yr | 6 |
| Phosphorus | ↑ Improving | -3.91 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | -0.09 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (55 observations).
Estimated open water season: 227 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-16 (2024) | 2013-05-13 (2013) |
| Ice-In | 2005-11-29 (2005) | 2024-01-04 (2024) |
Most recent ice-out: 2025-04-17
Reservoir Info (USACE NID)
Otter Tail Lake is a man-made reservoir impounded by the Otter Tail Lake (completed 1936), built primarily for other on the Otter Tail River; gravity-type dam, 10 ft tall and 125 ft long.
- Surface area
- 14,745 ac
- Normal storage
- 506,000 ac-ft
- Max storage
- 557,200 ac-ft
- Drainage area
- 1,160 sq mi
- Hazard class
- Low
- Owner
- MNDNR-EWR
Source: USACE National Inventory of Dams, NID ID MN00209 · Operator website
EPA Impairment Status
Otter Tail 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 MN56-0242-00 · Official waterbody report
County Ranking
Ranked #36 of 66 lakes in Otter Tail County
Nearby Lakes in Otter Tail County
Frequently asked questions about Otter Tail Lake
What is the water quality grade for Otter Tail Lake?
- Otter Tail Lake in Otter Tail County, Minnesota has a water quality grade of A (Excellent). Water clarity: 12.1 ft visibility. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 5.5 µg/L. Maximum depth: 120 ft. Surface area: 14078.61 acres.
Is Otter Tail Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Otter Tail Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 5.5 µg/L. Always check local health department advisories before swimming.
How deep is Otter Tail Lake?
- Otter Tail Lake has a maximum depth of 120 feet. The lake covers 14078.61 acres.
What fish are in Otter Tail Lake?
- Fish species found in Otter Tail Lake include black bullhead, black crappie, bluegill, brown bullhead, hybrid sunfish, lake sturgeon, largemouth bass, northern pike, pumpkinseed, rock bass, shorthead redhorse, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Otter Tail Lake is located in Otter Tail County, Minnesota.
When does Otter Tail Lake thaw?
- Otter Tail Lake typically has ice-out around Apr 16. Ice typically forms around Nov 29. The open water season is approximately 227 days.
Explore Otter Tail Lake across LakeGrade
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Where this data comes from
155 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
MNPCA155 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