North Turtle Lake
North Turtle Lake in Otter Tail County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 4 ft visibility. Phosphorus: 54.5 µg/L. Chlorophyll-a (algae): 22 µg/L. Maximum depth: 19 ft. Surface area: 1773.16 acres.
- Clarity
- 4 ft
- Max depth
- 19 ft
- Area
- 1,773 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 16
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near North Turtle Lake →
Next lake in Otter Tail County
Free interactive depth-contour map of North Turtle Lake, reaching a maximum surveyed depth of 15 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
North Turtle Lake is a 1,773-acre productive, nutrient-rich eutrophic lake in Otter Tail County, Minnesota with a maximum depth of 19 feet. Water quality is graded D based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 65 other monitored lakes in Otter Tail County, North Turtle Lake ranks #64 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-10. Grade methodology: LakeGrade methodology.
Watch North Turtle Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Grade onlyAlgae risk
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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 4 ft. Phosphorus level: 54.5 µg/L. Chlorophyll-a: 22 µg/L. Trophic State Index: 60.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4 ft | Not graded |
| Phosphorus | 54.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 22 µg/L | Poor |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near North Turtle Lake
Compare lakeside cabins, hotels, and vacation rentals near North Turtle 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around North Turtle Lake are listed below.
Top-rated places to stay near North Turtle Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 19 ft |
| Surface Area | 1,773 acres |
| Shoreline Length | 22.9 mi |
| Littoral Zone | 82% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- North Turtle LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing North Turtle Lake
DNR Fisheries Survey Summary
9 surveys on file from MN DNR Fisheries. Most recent: 2025-04-17 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 27.03 | 0.78 lb |
| Bluegill | 26.78 | 0.15 lb |
| Largemouth Bass | 24.49 | 1.83 lb |
| Yellow Perch | 21.04 | 0.13 lb |
| Yellow Bass | 19.14 | 0.52 lb |
| Black Crappie | 9.60 | 0.33 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.
Black Bullhead
Bluegill
Largemouth Bass
Yellow Perch
From the 2025-04-17 survey
North Turtle Lake is a 1,484-acre eutrophic (fertile) lake located in central Otter Tail County immediately northeast of Underwood, MN. North Turtle Lake is part of the Otter Tail River Watershed. There are no navigable inlets or outlets. The immediate watershed is composed primarily of agricultural land interspersed…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for North Turtle Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — North TurtleFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — North TurtleFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — North TurtlePublic 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 | → Stable | +0.015 m/yr | 5 |
| Phosphorus | ↑ Improving | -10.61 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -4.34 µg/L/yr | 4 |
Ice Season
Historical ice data from Minnesota DNR (5 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2021-03-29 (2021) | 2023-04-30 (2023) |
| Ice-In | 2023-11-25 (2023) | 2023-11-25 (2023) |
Most recent ice-out: 2023-04-30
EPA Impairment Status
North Turtle 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 MN56-0379-00 · Official waterbody report
County Ranking
Ranked #64 of 66 lakes in Otter Tail County
Nearby Lakes With Higher Grades
North Turtle Lake holds Grade D. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Otter Tail County
Frequently asked questions about North Turtle Lake
What is the water quality grade for North Turtle Lake?
- North Turtle Lake in Otter Tail County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 4 ft visibility. Phosphorus: 54.5 µg/L. Chlorophyll-a (algae): 22 µg/L. Maximum depth: 19 ft. Surface area: 1773.16 acres.
Is North Turtle Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. North Turtle Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 22 µg/L. Always check local health department advisories before swimming.
How deep is North Turtle Lake?
- North Turtle Lake has a maximum depth of 19 feet. The lake covers 1773.16 acres.
What fish are in North Turtle Lake?
- Fish species found in North Turtle Lake include black bullhead, black crappie, bluegill, brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow bullhead, yellow perch. North Turtle Lake is located in Otter Tail County, Minnesota.
When does North Turtle Lake thaw?
- North Turtle Lake typically has ice-out around Apr 16.
Are there boat ramps on North Turtle Lake?
- North Turtle Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include North Turtle Lake. Public access is listed as yes.
Explore North Turtle Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Otter Tail County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Alexandria Lakes area
Top lakes and where to stay in the Detroit Lakes Area area
Top lakes and where to stay in the Otter Tail County area
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Red River of the North Watershed, ranked by water quality
High nutrients, frequent algae, reduced clarity
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near North Turtle Lake
Other Grade D Lakes in Minnesota
Eutrophic Lakes in Minnesota
Compare North Turtle Lake With Nearby Lakes
Where this data comes from
80 measurements from 2 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
MNPCA80 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 (2)
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