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Engineering

Greentree/McKenna Watershed Study

Project Details

Project Information

Latest Update

5/22/2023 Update: 
The Greentree/McKenna Watershed Study Final Report is now available for viewing.  

The City has developed answers to commonly asked questions for our watershed studies. Please see the Watershed Study Learning Hub page for answers to commonly asked questions.

Project Overview

The City of Madison has completed a watershed study in the Greentree/McKenna watershed. The watershed study identified causes of existing flooding and then crafted potential solutions to try to reduce flooding. The study used computer models to assist with the evaluations.

A local engineering consultant, MSA Professional Services, completed the study. The Greentree/McKenna watershed drains to the south toward the Upper Badger Mill Creek ponds near Prairie Ridge Park.
For more information, please see the Flash Flooding Story Map. *Note: Please view the story map using Firefox or Google Chrome browsers. Story maps are not viewable with Internet Explorer.

Greentree/McKenna Watershed Map

Still have questions? Get some answers here from our additional information page on the Watershed Studies.

Timeline

The watershed study took approximately 30 months to complete.  The first studies took longer as the City worked through the best processes and approaches for this new flood study initiative.

Public Involvement

Questions and comments can be emailed to the Project Contact at anytime.  There were also a number of points of contact during this project where the public was encouraged to give feedback. Information is summarized below:

Public Information Meetings

A virtual public information meeting is scheduled for this project 6 p.m., May 12, 2022, via Zoom. Registration prior is required.

Focus Groups

The City of Madison Engineering Division set locations, times, and dates for focus group meetings for the Greentree/McKenna Watershed. The meetings were requested by community members, and were open to the public, but the conversation was tailored to gathering more information on flooding issues in the meeting area. The focus groups looked further into the issues that caused flooding in the last few years specific to each meeting area. The Engineering Division worked with alders, and residents to find a date, location and time that worked for the specific areas.

Greentree/McKenna Focus Groups Areas

The meetings lasted approximately one hour, and most meetings were held outside, rain or shine, in a walk-and-talk format.

The following focus group meetings were held for this watershed:

  • Gammon - Schroeder - Thursday 7/30/20 4:00-5:00 PM - West side of Gammon Rd. at Schroeder Rd.
  • Laurie Drive -  Thursday 7/23/20 9:00-10:00 AM - SW corner of Laurie Dr. and Schroeder Rd.
  • Park Edge Drive - Tuesday 7/28/20 9:00-10:00 AM - Park Edge Dr. at Georgetown Ct.
  • Park Edge Drive - Thursday 7/30/20 6:30-7:30 PM - Park Edge Dr. at Georgetown Ct.
  • Park Ridge Drive -  Tuesday 7/28/20 11:00 AM-12:00 PM - Park Ridge Dr. near The Lexington Condominiums
  • Park Ridge Drive - Wednesday 7/29/20 6:30-7:30 PM - Park Ridge Dr. near The Lexington Condominiums
  • Piping Rock Road - Wednesday 7/29/20 4:00-5:00 PM - SW corner of Piping Rock Rd. and Winston Dr.
  • Saalsaa Road - Wednesday 7/29/20 2:00-3:00 PM - NW corner of Saalsaa Rd. and Hammersley Rd.
  • Struck Street -  Thursday 7/23/20 11:00 AM-12:00 PM Struck St. - Next to the John Powless Tennis Center

Public Comment Period

A 30-day Public Comment Period will be held for the public to review the Draft Final Report and provide comments.  The public comments and response to comments will be included in the Final Report.

Prioritization Survey

There are many proposed recommendations from each watershed study.  The cost of the recommendations far outweighs the City's budget to implement them.  The public is asked to complete a survey to help the City prioritize which solutions are implemented first.Complete a survey to help City Engineering prioritize flooding improvement projects.

Existing Conditions Flood Mapping

The watershed model evaluated numerous design storm events and the City created an online viewer for the 1% chance (100-yr) storm event.

Proposed Flood Reduction Solutions

The watershed study resulted in many proposed flood reduction solutions. These solutions are concepts and show what it would take to meet the City's flood reduction targets. Only solutions included in the Capital Improvement Program budget are in process of design or construction and public outreach efforts are conducted for those projects separately from this study.

Background

The City of Madison has 22 watersheds. Watersheds  are an area of land that drain to the same location (the outlet).
There is a stormwater drainage system in all watersheds. This system is what conveys the stormwater to the outlet of the watershed. The current statistics on the City of Madison's stormwater drainage system can be found on the Stormwater webpage.

The City's system dates back to the 1880s. Very few, if any, standards were available in the 1880s. As the City developed, so did the guidance for design and construction. Today, we have comprehensive City, State, and Federal regulations to guide design and construction. The area of the City you live in used the regulations in place at the time it was developed. You can view the StoryMap  to see what the regulations were for your neighborhood.

The extreme storm events in 2018 shed light on the deficiencies of the City’s stormwater drainage system. Many areas of the City experienced devastating flooding. This prompted the City to begin a comprehensive watershed study program in 2019. The intent of the program is to study each of the City’s watersheds one-by-one. The studies will help us to understand the causes of flooding. The studies will also provide recommended solutions to reduce the risk of flooding.

The watershed studies result in a list of proposed mitigation measures. Once constructed, the measures will reduce the risk of flooding to specific areas of the City. These mitigation measures are generally very costly. Due to limited stormwater management funding, all the mitigation measures cannot be implemented at one time.

The average Stormwater Utility Capital Budget each year is approximately $12 million. Within that, an average of about $2.4 million is used for flood mitigation. As of late 2021, recommended flood mitigation measures for the first five watershed studies were identified. The total cost from the first five studies is approximately $125 million. We expect the remaining 17 watershed studies will have similar flood mitigation project needs. Implementation of these flood mitigation measures will take many decades.

The Stormwater Utility funds the stormwater management for the City. This includes the construction, operation, and maintenance of the entire stormwater drainage system. The Stormwater Utility rates are set each year consistent with Wisconsin Statute. § 66.0821(4)  and as described in Madison General Ordinance section 37.05 . These rates are under the purview of the public service commission. The rates are required to be deemed “reasonable” to comply with state statute. During the annual budgeting process, the City tries to balance the stormwater needs with the stormwater rate charged to its customers. These needs include:

  • Implementation of flood mitigation measures
  • Replacement, extension, and upgrades of existing the existing stormwater system
  • Mandated water quality needs and requirements

When possible, the City attempts to get grant funding to partially fund the flood mitigation measures. Grant funding makes up a small part of the funding needed for stormwater management.

The City has created a draft prioritization process. This process creates a proposed order to construct the flood mitigation measures. This process accounts for many factors including:

  • Impact on emergency services,
  • Location of vulnerable populations,
  • If the project also improves stormwater quality,
  • Whether other projects are occurring nearby, and
  • If outside funding is available.

Additional Resources

Report Flooding

If anyone has experienced flooding, and is willing to share with the City, please report it on the City's website. Even if a homeowner reported flooding to 2-1-1, FEMA, or a City official, the City needs standardized information to create stormwater models that show existing flooding conditions. The flood data helps the City prioritize different flood projects and future watershed studies. Please report any flooding you’ve experienced.

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