Lake Level Targets and Records
Wisconsin DNR orders from 1979 set each lake's summer and winter levels, and Dane County runs the dams to keep within them. In summer (from the first spring runoff after March 1) the county aims for the middle of the range; from Nov. 1 it holds levels between the winter minimum and the summer minimum.(Dane County LWRD) Since a 2021 county board resolution, the department can move levels within those ranges ahead of forecast storms.(Dane County LWRD)
| Lake | Acres | Summer range (ft) | Winter minimum (ft) | Record high (ft) | 100-year flood (ft) | Dam |
|---|---|---|---|---|---|---|
| Mendota | 9,842 | 849.6-850.1 | 848.2 | 852.74 (June 6, 2000) | 852.8 | Tenney Park Dam |
| Monona | 3,274 | 844.7-845.2 | 842.2 | 848.52 (Sept. 6, 2018) | 847.7 | Babcock Park Lock and Dam |
| Waubesa | 2,080 | 844.5-845.0 | 842.0 | 847.86 (Sept. 6, 2018) | 847.0 | Babcock Park Lock and Dam |
| Kegonsa | 3,209 | 843.0-843.5 | 841.85 | 845.74 (June 21, 2018) | 845.8 | LaFollette County Park Lock and Dam |
Elevations in feet above NGVD29, as Dane County reports them. To compare with FEMA's 2009 flood maps (NAVD88), subtract 0.2 ft.(Dane County LWRD)
- Monona's 2018 record, 848.52 feet, is above its 100-year flood elevation of 847.7. Waubesa's 2018 record (847.86) is above its 847.0 too.(Dane County LWRD)
- Mendota's record still dates to June 2000. NWS lists its highest gauge readings as June 5, 2000, June 14, 2008 and Aug. 23, 2018, in that order.(NWS)
- Properties in the 100-year floodplain count as high risk under the National Flood Insurance Program, and new building there must meet local floodplain zoning.(Dane County LWRD)
Check the Lakes Now
- Dane County's lake level page posts daily levels from USGS against each lake's targets.(Dane County LWRD) USGS's own gauges: Lake Mendota (05428000), Lake Monona (05429000), Lake Waubesa (05429485).
- NWS river forecasts for the lakes are on its water prediction site, for example Lake Mendota (MDAW3).
- Lake levels from USGS are provisional until reviewed, usually within 6 months after Sept. 30.(Dane County LWRD)
The Big Floods
- June 2000: Mendota reached its record, 852.74 feet, on June 6.(Dane County LWRD) FEMA declared a disaster for severe storms, tornadoes and flooding that included Dane County (DR-1332).(OpenFEMA)
- June 2008: rain fell in Madison on all but three days from June 1 to 14, and southern Wisconsin got 6 to 12 inches.(NWS) The disaster declaration (DR-1768) included individual assistance for Dane County.(OpenFEMA)
- August 2018: NWS describes major flash flooding across Dane County and flooding of the Yahara chain of lakes.(NWS) The Madison airport recorded 3.78 inches of rain on Aug. 20, and the Madison Area record shows 10.40 inches for the month.(NOAA ACIS) Monona and Waubesa peaked on Sept. 6 at record levels.(Dane County LWRD) The federal declaration (DR-4402) covers Aug. 17 to Sept. 14, 2018.(OpenFEMA)
Every federal declaration that included Dane County is listed on the weather and hazards hub. Of the 19, 9 name flooding.
Your House's Flood Risk
- Flood maps: FEMA's flood maps, the county's DCiMap floodplain layer, the DNR's floodplain viewer and Madison's watershed flood-risk map are all covered in Dane County maps. Look up a specific address with property lookup.
- Beyond the lakes: Dane County Emergency Management says flood risk in the county is increasing, citing high groundwater and lake levels.(Dane County EM)
- Flash flood warnings reach phones through Wireless Emergency Alerts, which cover flash floods as well as tornadoes.(Dane County EM) Sirens and weather warnings covers the other ways to get alerts.
- Runoff from a neighbor's yard is a separate question with its own rules: see neighbor water runoff. For a wet basement in an older house, see older basements.
Flood Insurance
- Homeowners insurance usually doesn't cover flooding. Flood insurance is a separate policy.(FEMA) The City of Madison notes it's available even outside a FEMA floodplain.(City of Madison)
- Top-down vs. bottom-up water: Wisconsin's insurance commissioner says water from the top down, like ice dam seepage, is generally covered by a standard homeowners policy; water from the bottom up needs flood insurance.(OCI)
- Limits: National Flood Insurance Program home policies cover up to $250,000 for the building and $100,000 for belongings.(FloodSmart)
- Basements: personal belongings kept in a basement aren't covered, nor are landscaping, decks, fences or temporary housing.(FloodSmart)
- Waiting period: coverage usually starts 30 days after you buy. There's no wait when you buy it while getting, increasing, extending or renewing a mortgage.(FloodSmart)(FEMA) Don't wait for a forecast.
- Buy through your insurance agent, or call the NFIP at (877) 336-2627 for help finding a provider.(FEMA)
If Your Basement Floods
- Don't go into a flooded basement while the power is on. Call MGE (608-252-7000) to disconnect power and gas before cleanup or pumping.(MGE)(MGE)
- Meters that were under water must be replaced by MGE, at no charge. A licensed electrician must inspect water-damaged panels and wiring before power is turned back on, and flooded gas valves and appliance parts must be replaced.(MGE)
- Alliant Energy customers call 1-800-ALLIANT for gas leaks, downed lines and other emergencies.(Alliant Energy) See power outages for the rest.
Questions
What is the normal level of Lake Mendota?
Wisconsin DNR's 1979 order for the Tenney Park Dam sets a summer range of 849.6 to 850.1 feet and a winter minimum of 848.2 feet (NGVD29). Dane County aims for the middle of the summer range. Its record high is 852.74 feet, on June 6, 2000.
Who controls the lake levels in Madison?
Dane County's Land and Water Resources Department operates the dams at Tenney Park, Babcock Park and LaFollette Park within ranges set by Wisconsin DNR orders.
How do I know if my house is in a flood zone?
Search your address on FEMA's Flood Map Service Center or the county and city maps covered in our Dane County maps guide. Being outside a mapped flood zone doesn't mean a house can't flood.
Does homeowners insurance cover flooding?
Most homeowners policies don't. Flood insurance is a separate policy, available outside high-risk zones too, and NFIP coverage usually starts 30 days after you buy it.