Lost Lake
Florence County, Wisconsin84 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Lost Lake. Here is what has been measured.
- Mesotrophic
- 45 ft max depth
- Public access
Lost Lake in Florence County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 10.6 ft visibility. Phosphorus: 13 µg/L. Maximum depth: 45 ft. Surface area: 84 acres.
Wisconsin DNR lists Smallmouth Bass as common on Lost Lake. DNR survey details →
Lost Lake is a 84-acre mesotrophic lake in Florence County, Wisconsin with a maximum depth of 45 feet. Water clarity is declining over recent sampling years. The lake supports 2 documented fish species including Smallmouth Bass and Trout. Public access is available with 1 public boat landing. Compared to the 11 other monitored lakes in Florence County, Lost Lake ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-05-05. Methodology: how these readings are compared.
What Lost Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10.6 ft of visibility
- Boat launch1 documented ramp
- Camping3 public campgrounds nearby
- Deep water45 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 Lost 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 Lost Lake
These are the measurements Wisconsin DNR publishes for Lost 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 10.6 ft. Phosphorus 13 µg/L. TSI 42.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 13µg/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. | 42 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Lost Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Lost Lake typically sits around 70°F at the surface in August. Summer average is about 73°F. Usually warmest in Jul (about 75°F) and coldest in Apr (about 46°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (46°F) to its warmest (75°F).
Typical surface water temperature by month, from 16 field readings (2024–2025) via the EPA Water Quality Portal. See the full Lost Lake water temperature breakdown →
Wisconsin DNR lists Smallmouth Bass as common on Lost Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lost Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. 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. 2 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
45 ft
Surface area
84 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Shoreline
1.3 mi
HydroLAKES / HydroSHEDS
Elevation
1,490 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lost LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Lost Lake
- Lost Lake0.4 km
- Lost Lake Cabins0.7 kmReserve
- Chipmunk Rapids1.3 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Stays via Stay22
Stays near Lost Lake
Compare lakeside cabins, hotels, and vacation rentals near Lost Lake in Florence 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 Lost Lake
Prices for Oct 9–11, 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 Lost Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Lost Lake
Water Quality Trend: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening5 years
Phosphorus
Improving-0.51 µg/L/yr6 years
Nearby Lakes in Florence County
Frequently asked questions about Lost Lake
Where is Lost Lake?
- Lost Lake is a lake in Florence County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Lost Lake?
- Lost Lake in Florence County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 10.6 ft visibility. Phosphorus: 13 µg/L. Maximum depth: 45 ft. Surface area: 84 acres.
Is Lost 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 Lost Lake?
- Lost Lake typically sits around 70°F at the surface in August, from 16 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Lost Lake?
- Lost Lake has a maximum depth of 45 feet. The lake covers 84 acres.
What fish are in Lost Lake?
- Fish species found in Lost Lake include Smallmouth Bass, Trout. Lost Lake is located in Florence County, Wisconsin.
What did the DNR fisheries survey find at Lost Lake?
- Wisconsin DNR lists Smallmouth Bass as common on Lost Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lost Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Lost Lake?
- Lost Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lost Lake. Public access is listed as yes.
Can I fish at Lost Lake?
- Lost Lake has 1 documented boat landing 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.
Are there campgrounds on Lost Lake?
- Lost Lake has 3 public campgrounds from USGS The National Map within 5 km, including Lost Lake, Lost Lake Cabins, Chipmunk Rapids. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Lost Lake across LakeQuality
Fish species and the cleanest lakes across Wisconsin
Fish species and best lakes in Florence 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
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Other Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Where this data comes from
39 measurements from 3 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX39 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
- Turbidity in Water
Monitoring station identifiers (3)
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)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles