Decorah Lake
Decorah Lake in Juneau County, Wisconsin has a water quality grade of D (Nutrient-rich). Phosphorus: 116 µg/L. Maximum depth: 15 ft. Surface area: 314 acres.
- Max depth
- 15 ft
- Area
- 314 acres
- Type
- Hypereutrophic
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Decorah Lake →
Next lake in Juneau County
Decorah Lake is a 314-acre highly nutrient-loaded hypereutrophic lake in Juneau County, Wisconsin with a maximum depth of 15 feet. Water quality is graded D based on 1 sampling years through 2021. 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. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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: 116 µg/L. Trophic State Index: 73.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 116 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay 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 grade measures nutrients and algae, not lodging — cabins and rentals around Decorah Lake are listed below.
Top-rated places to stay near Decorah Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 15 ft |
| Surface Area | 314 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Riverside ParkPublic
Fish Species
Click a species to see every graded 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.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 4 stations on file (most recent sample 2021).
Fish Species (DNR-rated)
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.
County Ranking
Ranked #2 of 2 lakes in Juneau County
Nearby Lakes With Higher Grades
Decorah Lake holds Grade D. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Juneau County
Frequently asked questions about Decorah Lake
What is the water quality grade for Decorah Lake?
- Decorah Lake in Juneau County, Wisconsin has a water quality grade of D (Nutrient-rich). Phosphorus: 116 µg/L. Maximum depth: 15 ft. Surface area: 314 acres.
Is Decorah Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Decorah Lake has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
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.
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.
Explore Decorah Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
12.7 mi away · cable-pulled, no boat wake
Fish species and top-graded lakes across Wisconsin
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 grade
Lakes in the Wisconsin River Watershed, ranked by water quality
Very high nutrients, dense algae, poor clarity
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More Wisconsin Lake Rankings
State Parks Near Decorah Lake
Other Grade D Lakes in Wisconsin
Hypereutrophic Lakes in Wisconsin
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)
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
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