Lake Kegonsa

Lake Kegonsa is the lowest lake in the Yahara chain and is surrounded primarily by agricultural land. Like Waubesa, Lake Kegonsa is one of the shallower lakes in the Yahara chain. Lake Kegonsa State Park, which contains prairie, forest and marsh habitats, is located along its northeastern shore. Most of the phosphorus entering the lake on an annual basis comes from upstream sources, although summer phosphorus levels may be driven by runoff within the watershed (McDonald & Lathrop, 2016).

Reductions to the phosphorus load entering Lake Kegonsa will come from work in the watersheds of the upper lakes and from improvements to agricultural cropping practices in the Lake Kegonsa watershed. Some improvements will also come from improving control of construction erosion in urban areas.

Lake Kegonsa by the numbers

Lake Kegonsa map

  • Watershed area: 34,560 acres
  • Surface area: 3,210 acres
  • Shoreline: 10 miles
  • Maximum depth: 31 feet
  • Mean depth: 17 feet
  • Flushing rate: 4 months

Water clarity

  • 3.4 feet or “good” according to Department of Natural Resources criteria for shallow lakes (2017)


Lake Kegonsa State Park beach is the only public beach on the lake and is not routinely monitored for blue-green algae.

Phosphorus levels

  • 0.128 mg/L or “poor” according to Department of Natural Resources criteria for shallow lakes (2017)

For an update on phosphorus reduction projects, see the State of the Lakes Annual Report.

Organizations supporting Lake Kegonsa

The following groups work on water quality issues in the Lake Kegonsa watershed. Consider contacting an organization near you to get involved!

Dane County
Friends of Lake Kegonsa
Public Health Madison & Dane County
Town of Dunn
Town of Pleasant Springs
UW-Madison Center for Limnology
Yahara Pride Farms
Yahara Watershed Improvement Network