Decorah Lake
Juneau County, Wisconsin314 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Decorah Lake. Here is what has been measured.
- Hypereutrophic
- Curly-Leaf Pondweed
- 15 ft max depth
- Public access
- Limited data
Decorah Lake in Juneau County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Phosphorus: 116 µg/L. Maximum depth: 15 ft. Surface area: 314 acres.
Wisconsin DNR lists Panfish as common on Decorah Lake. DNR survey details →
Decorah Lake is a 314-acre highly nutrient-loaded hypereutrophic lake in Juneau County, Wisconsin with a maximum depth of 15 feet. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing. Compared to the 1 other monitored lakes in Juneau County, Decorah Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2021-08-23. Methodology: how these readings are compared.
What Decorah Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing4 species recorded
Swimming conditions
Readings onlyLimited data
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 Decorah 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 Decorah Lake
These are the measurements Wisconsin DNR publishes for Decorah Lake, 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 116 µg/L. TSI 73.
| 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 | 116µg/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. | 73 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Decorah Lake
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR lists Panfish as common on Decorah Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Decorah Lake’s water-quality measurements separately. 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. 4 stations on file (most recent sample 2021).
Fish Species (DNR-rated)
Lake Details
Max depth
15 ft
Surface area
314 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
584 sq mi
HydroLAKES / HydroSHEDS
Shoreline
5.2 mi
HydroLAKES / HydroSHEDS
Elevation
866 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Riverside ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Decorah Lake
Compare lakeside cabins, hotels, and vacation rentals near Decorah Lake in Juneau 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 Decorah Lake are listed below.
Top-rated places to stay near Decorah 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 Decorah Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Decorah 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.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Decorah Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Mauston Wastewater Treatment FacilityMauston · 2.1 mi away · NPDES WI0024635Recent violation
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 Juneau County
Frequently asked questions about Decorah Lake
Where is Decorah Lake?
- Decorah Lake is a lake in Juneau County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Decorah Lake?
- Decorah Lake in Juneau County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Phosphorus: 116 µg/L. Maximum depth: 15 ft. Surface area: 314 acres.
Is Decorah Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Decorah Lake?
- Decorah Lake has a maximum depth of 15 feet. The lake covers 314 acres.
What fish are in Decorah Lake?
- Fish species found in Decorah Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Decorah Lake is located in Juneau County, Wisconsin.
What did the DNR fisheries survey find at Decorah Lake?
- Wisconsin DNR lists Panfish as common on Decorah Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Decorah Lake’s water-quality measurements separately. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Decorah Lake?
- Decorah Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Riverside Park. Public access is listed as yes.
Can I fish at Decorah Lake?
- Decorah 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.
Explore Decorah Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
12.7 mi away · cable-pulled, no boat wake
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Fish species and best lakes in Juneau County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its readings
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Where this data comes from
4 measurements from 1 monitoring station, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX4 samples · 2021
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
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