Lake Kegonsa
Dane County, Wisconsin3,200 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Lake Kegonsa. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- 3 aquatic invasives
- 32 ft max depth
- Public access
Lake Kegonsa in Dane County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 3.7 ft visibility. Phosphorus: 59.5 µg/L. Maximum depth: 32 ft. Surface area: 3200 acres.
Wisconsin DNR rates Panfish as abundant on Lake Kegonsa. DNR survey details →
Lake Kegonsa is a 3,200-acre productive, nutrient-rich eutrophic lake in Dane County, Wisconsin with a maximum depth of 32 feet. Water clarity is declining over recent sampling years. The lake supports 7 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available with 4 public boat landings. Compared to the 14 other monitored lakes in Dane County, Lake Kegonsa ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-04-10. Methodology: how these readings are compared.
Lake Kegonsa covers about 3,200 acres in Dane County. It has 4 public boat landings, so a lakefront rental is not the only way to get a boat on the water. Vrbo is where to look for cabins and lake homes around Lake Kegonsa, and Booking.com and Expedia search hotels near the lake for your dates.
What Lake Kegonsa is good for
From access and monitoring records, not editorial picks.
- Boat launch4 documented ramps
- Fishing7 species recorded
- Deep water32 ft surveyed max depth
- Big water3,200 acres
Lake Kegonsa Water Quality Summary (2026)
A printable one-page summary for Lake Kegonsa: clarity, phosphorus, algae, multi-year trend, depth, and fish — with sources.
Swimming conditions
Readings onlyRecreation use not supported
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.
Based on E. coli testing, Lake Kegonsa frequently exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 10.1% of 473 samples across 9 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Wisconsin’s current beach and health-department advisories before swimming.
Whether Lake Kegonsa 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 Lake Kegonsa
These are the measurements Wisconsin DNR publishes for Lake Kegonsa, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.7 ft. Phosphorus 59.5 µg/L. TSI 61.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 59.5µg/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. | 61 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Lake Kegonsa
Answers come straight from the public measurements and survey records on this page.
Current Conditions
USGS snapshot Jul 6, 2026, 5:00 AM from gauge 425715089164700 (Lake Kegonsa at Barber Drive Near Stoughton, WI). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
→ Lake Kegonsa water level: the live USGS gauge reading
Water Temperature
Lake Kegonsa typically sits around 66°F at the surface in October. Summer average is about 78°F. Usually warmest in Jul (about 80°F) and coldest in May (about 62°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (62°F) to its warmest (80°F).
Typical surface water temperature by month, from 48 field readings (2024–2025) via the EPA Water Quality Portal. See the full Lake Kegonsa water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Lake Kegonsa — clouds, ice, or an off-season gap in coverage. The most recent reading was high (205,116 cells/mL) on July 18, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Wisconsin DNR rates Panfish as abundant on Lake Kegonsa.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lake Kegonsa’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. Monitored by volunteers since 1989. 18 stations on file (most recent sample 2026).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Lake Kegonsa covering fish populations, stocking, water quality, and management. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2016Lake Kegonsa comprehensive survey, 2016Comprehensive Survey · WI DNR · 2016 (PDF)
Lake Details
Max depth
32 ft
Surface area
3,200 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
381 sq mi
HydroLAKES / HydroSHEDS
Shoreline
9.6 mi
HydroLAKES / HydroSHEDS
Elevation
840 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Pleasant SpringsPublic
- Fish Camp County ParkPublic
- Lake Kegonsa State ParkPublic
- South Quam DrivePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Lake Kegonsa
Compare lakeside cabins, hotels, and vacation rentals near Lake Kegonsa in Dane 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 Lake Kegonsa are listed below.
Top-rated places to stay near Lake Kegonsa
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 trip? Cabins and lodging at Lake Kegonsa → · more Wisconsin lake trips
Follow Lake Kegonsa’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Lake Kegonsa
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: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Improving-5.44 µg/L/yr4 years
Reservoir Info (USACE NID)
Lake Kegonsa is a man-made reservoir impounded by the Lake Kegonsa (completed 1938), built primarily for navigation on the YAHARA; gravity-type dam, 10 ft tall and 100 ft long.
- Surface area
- 2,716 ac
- Normal storage
- 2,716 ac-ft
- Max storage
- 16,300 ac-ft
- Drainage area
- 410 sq mi
- Hazard class
- Low
- Owner
- Dane County
All listed purposes: Navigation;Recreation.
Source: USACE National Inventory of Dams, NID ID WI01072 · Operator website
EPA Impairment Status
Lake Kegonsa is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life, Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit WI10027603 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Lake Kegonsa 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.
- Stoughton Wastewater Treatment FacilityStoughton · 5 mi away · NPDES WI0020338MajorRecent 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 Dane County
Frequently asked questions about Lake Kegonsa
Where is Lake Kegonsa?
- Lake Kegonsa is a lake in Dane County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Lake Kegonsa?
- Lake Kegonsa in Dane County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 3.7 ft visibility. Phosphorus: 59.5 µg/L. Maximum depth: 32 ft. Surface area: 3200 acres.
Is Lake Kegonsa safe to swim in?
- Based on E. coli testing, Lake Kegonsa frequently exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 10.1% of 473 samples across 9 seasons. That is a historical summary of past bacteria testing, not a current reading and not a swimming clearance. Bacteria levels can spike quickly after heavy rain, so whether Lake Kegonsa is safe to swim in today is a call for Wisconsin's water agency and the county health department; check their current beach advisories before you swim.
What is the water temperature of Lake Kegonsa?
- Lake Kegonsa typically sits around 66°F at the surface in October, from 48 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Lake Kegonsa?
- Lake Kegonsa has a maximum depth of 32 feet. The lake covers 3200 acres.
What fish are in Lake Kegonsa?
- Fish species found in Lake Kegonsa include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye, Catfish. Lake Kegonsa is located in Dane County, Wisconsin.
What did the DNR fisheries survey find at Lake Kegonsa?
- Wisconsin DNR rates Panfish as abundant on Lake Kegonsa. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lake Kegonsa’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.
What is the water level at Lake Kegonsa?
- The USGS snapshot on this page for Lake Kegonsa is 843.29 ft of water-surface elevation, recorded Jul 6, 2026, 5:00 AM at gauge 425715089164700. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.
Does Lake Kegonsa have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Lake Kegonsa (clouds, ice, or an off-season gap). The most recent reading was high (205,116 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Lake Kegonsa?
- Lake Kegonsa has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Pleasant Springs, Fish Camp County Park, Lake Kegonsa State Park, South Quam Drive. Public access is listed as yes.
Can I fish at Lake Kegonsa?
- Lake Kegonsa has 4 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 Lake Kegonsa 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 Dane County
Species activity outlook by water temperature and season
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Where to stay at Wisconsin's top lakes, each with its readings
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Compare Lake Kegonsa With Nearby Lakes
Where this data comes from
102 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_WQX102 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
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