South Turtle Lake
Otter Tail County, Minnesota, near Underwood. DNR lake ID 56037700.
South Turtle Lake is an 836.6-acre lake in Otter Tail County, Minnesota, near Underwood. Its deepest point reaches 35 ft, and about 48% of the lake is shallower than 15 feet. Summer water clarity averages 15.7 feet in Minnesota Pollution Control Agency monitoring, which places it in the mesotrophic nutrient class. It is not on the DNR infested waters list as of September 2026. DNR surveys document walleye, northern pike, largemouth bass, black crappie, bluegill, yellow perch.
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Quick facts
| DNR lake ID | 56037700 |
|---|---|
| County | Otter Tail County, near Underwood |
| Surface area | 836.6 acres |
| Maximum depth | 35 ft |
| Share under 15 ft | 48% |
| Water clarity (summer) | 15.7 ft through 2025 |
| Phosphorus (summer) | 19.6 µg/L |
| Algae, chlorophyll-a (summer) | 3.5 µg/L |
| Nutrient class | Mesotrophic |
| Clarity trend | Murkier (2016 to 2025) |
| Invasive species | Not on DNR infested waters list (Sept 2026) |
| Public water accesses | 1 |
Water quality
Summer averages from Minnesota Pollution Control Agency monitoring through 2025: clarity 15.7 ft, phosphorus 19.6 µg/L, algae (chlorophyll-a) 3.5 µg/L. Using the Carlson trophic state index, South Turtle Lake rates as mesotrophic. Summer clarity trend 2016 to 2025: murkier.
Fishing on South Turtle Lake
The most recent DNR standard fish survey was in 2017 (9 years ago). Catch per net is compared with the DNR’s typical range for lakes of the same type.
| Species | Net | Catch per net | Typical range |
|---|---|---|---|
| Walleye | gill | 1.67 | 1.3 to 5.5 |
| Northern pike | gill | 6.67 | 3.1 to 8.5 |
| Northern pike | trap | 0.92 | n/a |
| Yellow perch | gill | 0.89 | 2.5 to 24.2 |
| Yellow perch | trap | 0.08 | 0.5 to 2.7 |
| Black crappie | gill | 1.0 | 0.5 to 2.7 |
| Black crappie | trap | 0.92 | 0.7 to 3.2 |
| Bluegill | gill | 18.44 | n/a |
| Bluegill | trap | 24.33 | 5.6 to 42.3 |
| Largemouth bass | gill | 3.22 | 0.3 to 1.2 |
| Largemouth bass | trap | 1.0 | 0.3 to 1.1 |
| Pumpkinseed | trap | 1.08 | 1.7 to 8.2 |
| Hybrid sunfish | gill | 0.56 | n/a |
| Hybrid sunfish | trap | 1.08 | n/a |
Walleye catch was within the typical range for similar lakes in that survey.
Largest fish measured in recent DNR samples: Northern pike 30.0 in (2017), Largemouth bass 18.0 in (2017), Walleye 24.0 in (2017).
Game and panfish documented since 2005: Walleye, Northern pike, Largemouth bass, Black crappie, Bluegill, Yellow perch, Pumpkinseed, Hybrid sunfish, Green sunfish, White sucker, Yellow bullhead, Brown bullhead, Black bullhead.
Fishing regulations
No lake-specific regulation found in Minnesota Rules or the DNR sunfish list. Statewide and zone regulations apply.
Regulations change. Confirm with the DNR before fishing.
Invasive species
Not on the Minnesota DNR infested waters list as of September 2026. That means no confirmed listing, not a guarantee the lake is free of invasive species.
Public boat access
- South Turtle Lake: 1 concrete slab launch ramp, 1 dock, 12 trailer spaces. 3 mi W of the city of Battle Lake to N shore. Directions
DNR water access records (2023). Confirm current conditions with the DNR.
Nearby lakes
- Fiske Lake 1.5 mi, Otter Tail County
- North Turtle Lake 2.2 mi, Otter Tail County
- Elbow Lake 2.3 mi, Otter Tail County
- German Lake 2.8 mi, Otter Tail County
- Long Lake 3.6 mi, Otter Tail County
- Crooked Lake 3.7 mi, Otter Tail County
- Silver Lake 3.8 mi, Otter Tail County
- Horseshoe Lake 3.9 mi, Otter Tail County
Questions about South Turtle Lake
How deep is South Turtle Lake?
South Turtle Lake reaches a maximum depth of 35 ft according to Minnesota DNR records. About 48% of the lake is shallower than 15 feet.
How big is South Turtle Lake?
South Turtle Lake covers about 836.6 acres in Otter Tail County, Minnesota.
How clear is South Turtle Lake?
Summer water clarity on South Turtle Lake averages 15.7 feet (Secchi depth) in MPCA monitoring through 2025. Its trophic state is mesotrophic.
Does South Turtle Lake have zebra mussels or other invasive species?
South Turtle Lake is not on the Minnesota DNR infested waters list as of September 2026. That means there is no confirmed listing; it is not a guarantee the lake is free of invasive species.
What fish are in South Turtle Lake?
Minnesota DNR surveys document walleye, northern pike, largemouth bass, black crappie, bluegill, yellow perch, pumpkinseed, hybrid sunfish, green sunfish, white sucker in South Turtle Lake. The most recent standard survey was in 2017.
Where is the public boat access on South Turtle Lake?
South Turtle Lake has 1 public water access site on DNR record: South Turtle Lake.
How is the walleye population on South Turtle Lake?
In Minnesota DNR net surveys from 2000 to 2017, walleye numbers on South Turtle Lake ran mostly within the typical range for similar lakes. Nets measure how many fish a lake holds, not where they’re biting, so local guides are the best source for current fishing.
Are there lake homes for sale on South Turtle Lake?
Homes on South Turtle Lake come up for sale throughout the year, and some sell before they’re ever publicly advertised. Tell us what you’re looking for and our agents will run a custom search and send you matching homes on South Turtle Lake and nearby lakes, including off-market opportunities when available.
What is it like to live on South Turtle Lake?
A mid-size lake with room for boating and fishing, about 48% shallow shoreline under 15 feet, and summer clarity around 15.7 feet. Conditions vary by property, so walk the frontage and ask us what similar homes have sold for.
Are there special fishing regulations on South Turtle Lake?
No lake-specific regulation was found for South Turtle Lake in Minnesota Rules or the DNR sunfish list. Statewide and zone regulations apply.
Ask us about South Turtle Lake
Whether you’re buying, selling, or just curious, our team works Otter Tail County lakes every day. Send us a note or call (218) 656-6469.
Sources: Minnesota DNR LakeFinder records, DNR fish surveys (latest 2017), DNR infested waters list (Sept 2026), Minnesota Rules 6264.0400 (April 2026), MPCA monitoring via the Water Quality Portal, DNR water access records (2023), LAGOS-US. Lakewide information from public data; it does not describe any specific property. Verify shoreline, bottom type, and depth at any frontage.