Tetonka Lake
Tetonka Lake in Le Sueur County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 3 ft visibility. Phosphorus: 289 µg/L. Chlorophyll-a (algae): 48 µg/L. Maximum depth: 35 ft. Surface area: 1357.8 acres.
- Clarity
- 3 ft
- Typical in August
- 77°F
- Max depth
- 35 ft
- Area
- 1,358 acres
- Type
- Hypereutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 2
- Open water
- 245 days
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Tetonka Lake →
Next lake in Le Sueur County
Free interactive depth-contour map of Tetonka Lake, reaching a maximum surveyed depth of 30 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Tetonka Lake is a 1,358-acre highly nutrient-loaded hypereutrophic lake in Le Sueur County, Minnesota with a maximum depth of 35 feet (19-foot average). Water quality is graded F based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 19 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 1 public boat landing. Compared to the 12 other monitored lakes in Le Sueur County, Tetonka Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-07. Grade methodology: LakeGrade methodology.
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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.
Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom
Water Quality Grade: F (Algae-prone)
Very murky, less than 3 ft of visibility. Phosphorus level: 289 µg/L. Chlorophyll-a: 48 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 289 µg/L | Poor |
| Chlorophyll-a (Algae) | 48 µg/L | Poor |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Tetonka Lake
Compare lakeside cabins, hotels, and vacation rentals near Tetonka Lake in Le Sueur 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 Tetonka Lake are listed below.
Top-rated places to stay near Tetonka Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Tetonka Lake typically sits around 77°F at the surface in August. Summer average is about 78°F. Usually warmest in Jul (about 79°F) and coldest in Sep (about 72°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 25 field readings (2022–2023) via the EPA Water Quality Portal. See the full Tetonka Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Tetonka Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (862,979 cells/mL) on July 18, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 35 ft |
| Average Depth | 19 ft |
| Surface Area | 1,358 acres |
| Shoreline Length | 11.6 mi |
| Littoral Zone | 40% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Tetonka LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Tetonka 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
18 surveys on file from MN DNR Fisheries. Most recent: 2023-11-01 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 35.46 | 0.75 lb |
| Bluegill | 16.51 | 0.24 lb |
| Walleye | 13.85 | 1.48 lb |
| Largemouth Bass | 13.64 | 1.56 lb |
| Green Sunfish | 10.18 | — |
| Freshwater Drum | 9.00 | 1.19 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
Walleye
Largemouth Bass
From the 2023-11-01 survey
A survey targeting age-0 Walleye was conducted at Tetonka Lake on 11 November 2023 using 1 hour 40 minutes of standard boat electrofishing. A total of 225 age-0 Walleyes were sampled for a catch rate of 134.7/hour on-time. Catch rates during fry-stocked years (n = 14) have averaged 64.2/hour on-time while non-stocked…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Tetonka Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — TetonkaFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — TetonkaFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — TetonkaPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.024 m/yr | 5 |
| Phosphorus | ↑ Improving | -178 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -19.3 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (125 observations).
Estimated open water season: 245 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-03 (2024) | 2018-04-29 (2018) |
| Ice-In | 1991-11-04 (1991) | 2024-01-07 (2024) |
Most recent ice-out: 2026-03-26
EPA Impairment Status
Tetonka 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 MN40-0031-00 · Official waterbody report
County Ranking
Ranked #6 of 13 lakes in Le Sueur County
Nearby Lakes in Le Sueur County
Frequently asked questions about Tetonka Lake
What is the water quality grade for Tetonka Lake?
- Tetonka Lake in Le Sueur County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 3 ft visibility. Phosphorus: 289 µg/L. Chlorophyll-a (algae): 48 µg/L. Maximum depth: 35 ft. Surface area: 1357.8 acres.
Is Tetonka Lake safe to swim in?
- Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Tetonka Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 48 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Tetonka Lake?
- Tetonka Lake typically sits around 77°F at the surface in August, from 25 EPA Water Quality Portal field readings (2022–2023). That is a typical value for the month, not a live reading.
How deep is Tetonka Lake?
- Tetonka Lake has a maximum depth of 35 feet and an average depth of 19 feet. The lake covers 1357.8 acres.
What fish are in Tetonka Lake?
- Fish species found in Tetonka Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, bowfin (dogfish), channel catfish, common carp, freshwater drum, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, smallmouth bass, walleye, white bass, white sucker, yellow bullhead, yellow perch. Tetonka Lake is located in Le Sueur County, Minnesota.
When does Tetonka Lake thaw?
- Tetonka Lake typically has ice-out around Apr 2. Ice typically forms around Dec 3. The open water season is approximately 245 days.
Does Tetonka Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Tetonka Lake (clouds, ice, or an off-season gap). The most recent reading was high (862,979 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Tetonka Lake?
- Tetonka Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Tetonka Lake. Public access is listed as yes.
Explore Tetonka 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 Le Sueur County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
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Very high nutrients, dense algae, poor clarity
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Where this data comes from
127 measurements from 7 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
MNPCA127 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 (7)
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