Mill Lake
Walworth County, Wisconsin271 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Mill Lake. Here is what has been measured.
- Mesotrophic
- 3 aquatic invasives
- 40 ft max depth
- Public access
Mill Lake in Walworth County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 7.5 ft visibility. Phosphorus: 15.3 µg/L. Maximum depth: 40 ft. Surface area: 271 acres.
Wisconsin DNR lists Panfish as common on Mill Lake. DNR survey details →
Mill Lake is a 271-acre mesotrophic lake in Walworth County, Wisconsin with a maximum depth of 40 feet. Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 2 public boat landings. Compared to the 18 other monitored lakes in Walworth County, Mill Lake ranks #11 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-12. Methodology: how these readings are compared.
Mill Lake covers about 270 acres in Walworth County. It has 2 public boat landings, so a lakefront rental is not the only way to get a boat on the water. For a place on the water, look through cabin and lake-house rentals near Mill Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Mill Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch2 documented ramps
- Fishing4 species recorded
- Deep water40 ft surveyed max depth
Swimming conditions
Readings onlyLow algae
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. Check local advisories before you swim.
Whether Mill Lake 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 Mill Lake
These are the measurements Wisconsin DNR publishes for Mill Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 7.5 ft. Phosphorus 15.3 µg/L. TSI 46.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 7.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 15.3µg/L | Good 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. | 46 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Mill Lake
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR lists Panfish as common on Mill Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Mill Lake’s water-quality measurements separately, and the water-quality trend over 7 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 2006. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
40 ft
Surface area
271 acres
Public access
Yes
Listed by Wisconsin DNR
Recreation & Access
- Ridge RoadPublic
- SterlingworthPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Mill Lake
Compare lakeside cabins, hotels, and vacation rentals near Mill Lake in Walworth 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.
Top-rated places to stay near Mill Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Follow Mill Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Mill 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.
Water Quality Trend: Improving
Based on 7 years of monitoring (2020–2026).
Water clarity
Improving7 years
Phosphorus
Stable+0.07 µg/L/yr7 years
Reservoir Info (USACE NID)
Mill Lake is a man-made reservoir impounded by the Lauderdale Lakes (completed 1840), built primarily for recreation on the Honey Creek; gravity-type dam, 14 ft tall and 425 ft long.
- Surface area
- 834 ac
- Normal storage
- 5,500 ac-ft
- Max storage
- 7,200 ac-ft
- Drainage area
- 12 sq mi
- Hazard class
- High
- Owner
- Lauderdale Lakes Lake Management District
Source: USACE National Inventory of Dams, NID ID WI00212 · Operator website · Matched by proximity (0.78 km)
Nearby Lakes in Walworth County
Frequently asked questions about Mill Lake
Where is Mill Lake?
- Mill Lake is a lake in Walworth County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Mill Lake?
- Mill Lake in Walworth County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 7.5 ft visibility. Phosphorus: 15.3 µg/L. Maximum depth: 40 ft. Surface area: 271 acres.
Is Mill Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Mill Lake?
- Mill Lake has a maximum depth of 40 feet. The lake covers 271 acres.
What fish are in Mill Lake?
- Fish species found in Mill Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Mill Lake is located in Walworth County, Wisconsin.
What did the DNR fisheries survey find at Mill Lake?
- Wisconsin DNR lists Panfish as common on Mill Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Mill Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Mill Lake?
- Mill Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Ridge Road, Sterlingworth. Public access is listed as yes.
Can I fish at Mill Lake?
- Mill Lake has 2 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 Mill Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Wisconsin
Fish species and best lakes in Walworth County
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
More lakes in Wisconsin
State Parks Near Mill Lake
Other Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Where this data comes from
64 measurements from 1 monitoring station, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX64 samples · 2020–2026
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
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory