Flood Mitigation Projects

The City has constructed a variety of projects over the years to help reduce flooding in neighborhoods and on streets. Additionally, the City does a number of annual, biannual and by each rain event preventative maintenance cleanings to keep stormwater sewers and waterways clear so the infrastructure moves water through the system effectively. Below, find a number of ways the City works to maintain stormwater infrastructure and see some of the recent projects that have been constructed.

Ongoing Stormwater System Maintenance

Annual maintenance

  • Willow Creek Basin Cleaning
    • City Engineering has a basin on University Avenue that collects rainwater. In Spring of 2018, Engineering crews removed 305 cubic yards of debris.
  • Biannual Catch Basin Cleaning
    • In April and October of every year, City crews clean catch basins in the City. During this clean, on average, crews clean approximately 1,200 structures and clear, on average, 480 tons of debris, per season since 2016.
  • Priority Grate Cleaning
    • After and prior to rain events, City crews clear 763 structures of debris which allows stormwater to flow through them more effectively. Priority Grates would include anything from inlets to dead ends and big grates on large storm sewer.
  • ~10 miles of storm sewer built/replaced annually
  • Streets Division maintenance by the numbers for 2021:
    • Total miles swept (when sweeping the City multiple times): 58,684
    • Total tonnage of debris collected: 6,473
  • Greenway mowing/debris removal – all the stuff we do to maintain our system in an attempt to keep the conveyance system clean.

Current Projects

In addition to the annual maintenance activities listed above, the City designs and constructs larger flood mitigation projects.  See the links below for some of the current and completed projects.

Past Projects

Mendota-Grassman Greenway Flood Mitigation and Restoration Design

The City of Madison's Mendota-Grassman Greenway drainage system consists of a series of connected culverts and shallow greenways that carry very large volumes of stormwater from the Stricker's Mendota Watershed out to Lake Mendota. Before the flood mitigation project, these connected greenways were highly vegetated with a shallow channel and wide, flat overbanks, and the culvert sizes and configurations were not optimized to carry the stormwater flows that were needed. Homes adjacent to the greenways have repeatedly flooded in the past during large storm events. 

In response, City Engineering designed and constructed the Mendota-Grassman Greenway Flood Mitigation and Restoration Design Project to mitigate the recurring flooding in this neighborhood and to restore the greenways to native vegetation to create a resilient stormwater system while increasing urban greenspace biodiversity.

The project was constructed in 2023-2024 with restoration efforts continuing into 2026. It included the following improvements:

  • Replacement and lowering of the existing culvert with a 5'x12' concrete box at University Avenue to increase capacity
  • Replacement of the existing culvert with dual 4'x10' concrete boxes at Camelot Drive to increase capacity
  • 2,600 feet of channel improvements, which included lowering and widening of the channel, the installation of rock riprap, and the restoration of vegetation to native plants, trees, and shrubs
The Mendota-Grassman Greenway shortly after construction was completed with the new channel grading, rock riprap, and plantings in view.

For more information, please visit the Mendota-Grassman Greenway Flood Mitigation and Restoration Design project webpage. 

McKenna Blvd. Flood Mitigation Project

The City of Madison's West Badger Mill Creek - Elver Park Greenway is a channel that carries stormwater from as far north as the Beltline, through Greentree Pond, and under McKenna Boulevard to the pond in Elver Park. Many homes and businesses are located directly adjacent to this greenway, including homes located on cul-de-sacs along Park Edge Drive, multifamily homes in the vicinity of Schroeder Road, and residential and commercial area along Struck Street. Since 2016, Park Edge Drive residents have experienced several rainstorms where water from the greenway flooded the neighborhood and entered their homes. This impact was most severe in August 2018. Additionally, McKenna Boulevard, which is a main thoroughfare through the neighborhood and houses police and fire stations for the west side of the City, has overtopped and become impassible several times. During flooding in August 2018, several properties along Struck Street also experienced inundation and a senior apartment and assisted living facility needed to be evacuated.

In response, City Engineering designed and constructed the McKenna Blvd Flood Mitigation Project to mitigate the recurring flooding in this neighborhood, on McKenna Boulevard, and along Struck Street.

Construction of Phase 1 was completed between July 2019 and May 2020 and included the following improvements:

  • Three existing pipes under McKenna Boulevard were removed and replaced with two 5' tall by 10' wide box culverts and two 5' tall by 12' wide box culverts, which greatly increased flow capacity under the road. This work included constructing new inlet and outlet wing walls.
  • Existing concrete channel was removed and replaced with a new concrete channel 1.5 feet lower than its previous level.
  • A retaining wall was constructed along the west edge of the greenway to provide significantly improved flow capacity in the channel that runs adjacent to Greentree Landfill.
  • Existing metal pipes at the outlet of Greentree Pond were removed and replaced with two 4' tall by 8' wide box culverts. The pond outlet and channel were also realigned to point southwest, rather than west, to prevent flows from going directly towards the back side of homes on Falmouth Court.

Construction of Phase 2 was completed between June 2020 and August 2020 and included the following improvements:

  • Existing metal pipes at the inlet of Greentree Pond were removed and replaced with four 42" concrete pipes. The new pipes have invert elevations 1.5' lower than the old pipes.
  • The natural channel between Greentree Pond and Schroeder Road was excavated to be 1.5 feet lower than the old channel.
  • Three existing pipes under Schroeder Road were removed and replaced with two 4' tall by 8' wide box culverts, which have capacity to carry the 1% chance storm without overtopping onto Schroeder Road. These culverts were realigned to discharge south-southwest, away from the mixed-use path, and the new culverts were set 1.5 feet lower than the old pipes.
  • The Schroeder Road profile near Struck Street was reshaped to create a low point that better facilitates street drainage.
  • Existing concrete channel was removed and replaced with a natural channel that is lower than the old channel and has a 2' deep pool of standing water.
The McKenna Blvd. Flood Mitigation Project following construction with the 4 new box culverts under Mckenna Blvd. in view.

For more information, please visit the McKenna Blvd. Flood Mitigation Project webpage. 

Hawk's Landing Flood Mitigation

For information on this project, please visit the Hawk's Landing Flood Mitigation project webpage. 

Lower Badger Mill Creek Pond

For information on this project, please visit the Lower Badger Mill Creek Pond project webpage. 

Southwest Bike Path/Waite Circle Culvert Reconstruction

For information on this project, please visit the Southwest Bike Path/Waite Circle Culvert Reconstruction project webpage. 

University Avenue Relief Pipe Phase II

For information on this project, please visit the University Avenue Relief Pipe Phase II project webpage. 

Impact Fees for Drainage and Stormwater

  • LBMC
  • UBMC
  • Valley View
  • West side drainage
  • Mineral Pont Rd drainage
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