Tonseth Lake
Otter Tail County, Minnesota149 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Tonseth Lake. Here is what has been measured.
- 27 ft max depth
- Public access
- Limited data
Tonseth Lake in Otter Tail County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 10 ft visibility. Maximum depth: 27 ft. Surface area: 148.98 acres.
Minnesota DNR's Standard Survey on June 14, 1999 caught 0.50 walleye per gill net at Tonseth Lake. DNR survey details →
Tonseth Lake is a 149-acre lake in Otter Tail County, Minnesota with a maximum depth of 27 feet (15-foot average). 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.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-01. Methodology: how these readings are compared.
Tonseth Lake covers about 150 acres in Otter Tail County. The median ice-out date is April 15, which is when the open-water season begins. If you are planning to stay, you can search lake houses and cabins around Tonseth Lake on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
What Tonseth Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10 ft of visibility
- Fishing12 species recorded
- Ice seasonIce-out around Apr 15
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Tonseth Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Tonseth Lake
These are the measurements Minnesota PCA publishes for Tonseth Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 10 ft. TSI 44.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 44 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Tonseth Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Tonseth Lake typically sits around 67°F at the surface in October. Summer average is about 74°F. Usually warmest in Jul (about 76°F) and coldest in May (about 58°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (58°F) to its warmest (76°F).
Typical surface water temperature by month, from 25 field readings (2023–2025) via the EPA Water Quality Portal. See the full Tonseth Lake water temperature breakdown →
Minnesota DNR's Standard Survey on June 14, 1999 caught 0.50 walleye per gill net at Tonseth Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Tonseth Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 1999-06-14 (Standard Survey).
2 surveys on file · most recent 1999-06-14 (Standard Survey)
27 years old| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 55.69 | 3–8 in 1999-06-14 | 0.12 lb |
| Largemouth Bass | 38.42 | 5–18 in 1999-06-14 | 0.77 lb |
| Yellow Bullhead | 12.31 | 5–12 in 1999-06-14 | 0.4 lb |
| Hybrid Sunfish | 10.34 | 3–8 in 1999-06-14 | 0.24 lb |
| Black Crappie | 7.82 | 4–12 in 1999-06-14 | 0.34 lb |
| Pumpkinseed | 7.58 | 3–7 in 1999-06-14 | 0.15 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
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
Yellow Bullhead
Hybrid Sunfish
From the 1999-06-14 survey
Tonseth Lake is located in west-central Otter Tail County approximately eight miles southeast of Erhard, MN. Tonseth Lake is a 156-acre moderately fertile lake that is part of the Otter Tail River Watershed. Two small intermittent inlets are located along the north shoreline of the lake and an outlet to Kempfer Lake…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Tonseth Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — TonsethFisheries Lake Survey · MN DNR LakeFinder
Lake Details
Max depth
27 ft
Average depth
15 ft
Surface area
149 acres
Shoreline
3.2 mi
Littoral zone
53%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
7 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,365 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Tonseth Lake
Compare lakeside cabins, hotels, and vacation rentals near Tonseth 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.
Top-rated places to stay near Tonseth Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Fish Species
Click a species to see every lake where it is documented.
Fishing Tonseth Lake
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving6 years
Ice season
Typical ice-out
Apr 15
Earliest Mar 22, 2012 · Latest May 9, 2013
Typical ice-in
Nov 21
Earliest Nov 4, 1991 · Latest Dec 9, 2016
Most recent ice-out
May 3
2022
76 observations · Minnesota PCA ice records
Nearby Lakes in Otter Tail County
Frequently asked questions about Tonseth Lake
Where is Tonseth Lake?
- Tonseth Lake is a lake in Otter Tail County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Tonseth Lake?
- Tonseth Lake in Otter Tail County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 10 ft visibility. Maximum depth: 27 ft. Surface area: 148.98 acres.
Is Tonseth Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Tonseth Lake?
- Tonseth Lake typically sits around 67°F at the surface in October, from 25 EPA Water Quality Portal field readings (2023–2025). That is a typical value for the month, not a live reading.
How deep is Tonseth Lake?
- Tonseth Lake has a maximum depth of 27 feet and an average depth of 15 feet. The lake covers 148.98 acres.
What fish are in Tonseth Lake?
- Fish species found in Tonseth Lake include black bullhead, black crappie, bluegill, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow bullhead, yellow perch. Tonseth Lake is located in Otter Tail County, Minnesota.
What did the DNR fisheries survey find at Tonseth Lake?
- Minnesota DNR's Standard Survey on June 14, 1999 caught 0.50 walleye per gill net at Tonseth Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Tonseth Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
When does Tonseth Lake thaw?
- Tonseth Lake typically has ice-out around Apr 15. Ice typically forms around Nov 21. The open water season is approximately 220 days.
Can I fish at Tonseth Lake?
- Public access to Tonseth Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
85 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA85 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate