Lake Tomah
Lake Tomah in Monroe County, Wisconsin has a water quality grade of D (Nutrient-rich). Phosphorus: 140 µg/L. Maximum depth: 19 ft. Surface area: 245 acres.
Wisconsin DNR lists Panfish as common on Lake Tomah. DNR survey details →
- Max depth
- 19 ft
- Area
- 245 acres
- Type
- Hypereutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Lake Tomah →
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Lake Tomah is a 245-acre highly nutrient-loaded hypereutrophic lake in Monroe County, Wisconsin with a maximum depth of 19 feet. Water quality is graded D based on 1 sampling years through 2026. 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. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyElevated nutrients
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)
No clarity data. Phosphorus level: 140 µg/L. Trophic State Index: 75.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 140 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 75 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay 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 grade measures nutrients and algae, not lodging — cabins and rentals around Lake Tomah are listed below.
Top-rated places to stay near Lake Tomah
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 →
Wisconsin DNR lists Panfish as common on Lake Tomah.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Lake Tomah D from EPA Water Quality Portal chemistry, 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
| Characteristic | Value |
|---|---|
| Maximum Depth | 19 ft |
| Surface Area | 245 acres |
| Public Access | Yes |
Lake Size & Watershed
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
Fish Species
Click a species to see every graded 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 data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -52.61 µg/L/yr | 4 |
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
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.
County Ranking
Ranked #1 of 1 lakes in Monroe County
Nearby Lakes With Higher Grades
Lake Tomah holds Grade D. 2 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 Monroe County
Frequently asked questions about Lake Tomah
Where is Lake Tomah?
- Lake Tomah is a lake in Monroe County, Wisconsin. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Tomah?
- Lake Tomah in Monroe County, Wisconsin has a water quality grade of D (Nutrient-rich). Phosphorus: 140 µg/L. Maximum depth: 19 ft. Surface area: 245 acres.
Is Lake Tomah safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Lake Tomah has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
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 a water-quality grade. LakeQuality grades Lake Tomah D from EPA Water Quality Portal chemistry, 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.
Explore Lake Tomah across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Wisconsin
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
Wisconsin's cleanest and most-polluted lakes, ranked
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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)
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
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