Lake Tomah
Monroe County, Wisconsin245 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Lake Tomah. Here is what has been measured.
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 2 aquatic invasives
- 19 ft max depth
- Public access
Lake Tomah in Monroe County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Phosphorus: 140 µg/L. Maximum depth: 19 ft. Surface area: 245 acres.
Wisconsin DNR lists Panfish as common on Lake Tomah. DNR survey details →
Lake Tomah is a 245-acre highly nutrient-loaded hypereutrophic lake in Monroe County, Wisconsin with a maximum depth of 19 feet. Overall water quality is improving over recent sampling years. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 4 public boat landings.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-05-31. Methodology: how these readings are compared.
Lake Tomah covers about 250 acres in Monroe County. It has 4 public boat landings, so a lakefront rental is not the only way to get a boat on the water. Vrbo is where to look for cabins and lake homes around Lake Tomah, and Booking.com and Expedia search hotels near the lake for your dates.
What Lake Tomah is good for
From access and monitoring records, not editorial picks.
- Boat launch4 documented ramps
- Fishing3 species recorded
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Lake Tomah is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Lake Tomah is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Tomah
These are the measurements Wisconsin DNR publishes for Lake Tomah, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 140 µg/L. TSI 75.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 140µg/L | Poor GoodFairPoor |
| 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. | 75 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Lake Tomah
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR lists Panfish as common on Lake Tomah.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lake Tomah’s water-quality measurements separately, and the water-quality trend over 4 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1986. 2 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Lake Tomah covering fish populations, stocking, water quality, and management. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2025Lake Tomah fish age and growth, 2025Fisheries Survey · WI DNR · 2025 (PDF)
- 2025Lake Tomah shocking and netting survey, 2025Netting Survey · WI DNR · 2025 (PDF)
- —Lake Tomah comprehensive survey, 2017-2022Comprehensive Survey · WI DNR (PDF)
Lake Details
Max depth
19 ft
Surface area
245 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
30 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2.8 mi
HydroLAKES / HydroSHEDS
Elevation
948 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Juneau StreetPublic
- Winnebago Park - NorthPublic
- Jones CourtPublic
- Winnebago Park - SouthPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Lake Tomah
Compare lakeside cabins, hotels, and vacation rentals near Lake Tomah in Monroe County, Wisconsin — 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Lake Tomah are listed below.
Top-rated places to stay near Lake Tomah
Prices for Oct 16–18, 4 adults. Change dates on the map below.
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 Wisconsin’s top lakes →
Follow Lake Tomah’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Lake Tomah
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Improving
Based on 4 years of monitoring (2021–2025).
Phosphorus
Improving-52.61 µg/L/yr4 years
Reservoir Info (USACE NID)
Lake Tomah is a man-made reservoir impounded by the Tomah Lake (completed 1936) on the Lemonweir; earth-type dam, 16 ft tall and 1,657 ft long.
- Surface area
- 225 ac
- Normal storage
- 980 ac-ft
- Max storage
- 2,250 ac-ft
- Drainage area
- 30.1 sq mi
- Hazard class
- High
- Owner
- City Of Tomah
Source: USACE National Inventory of Dams, NID ID WI00161 · Operator website
EPA Impairment Status
Lake Tomah is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life, Recreation.
Source: EPA ATTAINS assessment unit WI10002784 · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Lake Tomah under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Tomah Wastewater Treatment FacilityTomah · 1.1 mi away · NPDES WI0021318MajorRecent violation
- Chapman Brothers FarmsTomah · 2.1 mi away · NPDES WI0062774
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Monroe County
Frequently asked questions about Lake Tomah
Where is Lake Tomah?
- Lake Tomah is a lake in Monroe County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Lake Tomah?
- Lake Tomah in Monroe County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Phosphorus: 140 µg/L. Maximum depth: 19 ft. Surface area: 245 acres.
Is Lake Tomah safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Tomah is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Lake Tomah?
- Lake Tomah has a maximum depth of 19 feet. The lake covers 245 acres.
What fish are in Lake Tomah?
- Fish species found in Lake Tomah include Panfish, Largemouth Bass, Northern Pike. Lake Tomah is located in Monroe County, Wisconsin.
What did the DNR fisheries survey find at Lake Tomah?
- Wisconsin DNR lists Panfish as common on Lake Tomah. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lake Tomah’s water-quality measurements separately, and the water-quality trend over 4 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Lake Tomah?
- Lake Tomah has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Juneau Street, Winnebago Park - North, Jones Court, Winnebago Park - South. Public access is listed as yes.
Can I fish at Lake Tomah?
- Lake Tomah has 4 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Lake Tomah across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Wisconsin
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its readings
Wisconsin's cleanest lakes, ranked on agency measurements
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State Parks Near Lake Tomah
Other Lakes in Wisconsin
Hypereutrophic Lakes in Wisconsin
Where this data comes from
16 measurements from 1 monitoring station, 2021–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX16 samples · 2021–2026
Analytical methods
- Phosphorus by Colorimetry
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory