Roadside Inventory and Management

SEWISC continues to work with southeastern Wisconsin roadside maintenance crews to control populations of five invasive plant species which were originally mapped in 2011, 2012 and 2013 through the efforts of more than 150 southeast Wisconsin resident volunteers.  Wild parsnip (Pastinaca sativa)common and cut-leaved teasel (Dipsacus sylvestris and D. laciniatus), common reed grass (Phragmites australis) and Japanese knotweed (Polygonum cuspidatum) populations were the target of these inventory efforts.

In 2015 the Ozaukee Washington Land Trust partnered with SEWISC to schedule and hold meetings with key representatives in more than 100 cities, towns and villages in Washington, Sheboygan, Ozaukee, Milwaukee, Racine and Kenosha Counties.  The invasive species inventory data was shared with the local roadway managers during those meetings. Roadway managers expressed a need for additonal funding to control the populations, so SEWISC successfully set out to secure those funds.

Nearly $551,000 in Great Lakes Restoration Initiative funding through the Environmental Protection Agency was awarded to SEWISC for follow-up surveys and the control of 2,174 populations of our target invasive species along the roadways in our coastal Counties (Sheboygan, Ozaukee, Milwaukee, Racine and Kenosha). 2,224 populations were ultimately treated before grant funding was depleted and roadway managers were given tools to identify and control the target species long-term. We found that approximately 102 previously mapped populations were successfully eradicated by local roadway crews, but unfortunately during this project, another 1,251 populations were mapped (an increase of 58%), indicating poor overall roadway management protocols resulting in tremendous spread of these species over the past 7 years.   

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The EPA-funded project also included re-surveying target roadway populations that have spread to adjacent properties and providing educational information packets to those affected property owners. The 403 adjacent roadway populations mapped by residents in 2013 increased to 986 by 2020 (145% increase) demonstrating that poor roadway management has direct and detrimental impact to adjacent property owners. You can help your roadway managers to improve their management protocols.  Discuss this problem with your local government and request that they follow our Roadside Invasive Plant Management Plan. 

SEWISC ROW Invasive Species Management Plan page 1

How Roadway Managers Can Obtain Funding to Help Stop the Spread of Invasives on Local Roadways

Develop a program by following the guidelines in the SEWISC ROW Invasive Species Management Plan.  The basic elements of a program to contain and control invasive plants on right-of-ways are simple to prioritize and outline:

  • Adjust and customize ROW mowing to prevent spreading seed, and when possible, to prevent seed set in established patches.  In other words, don’t spread the species by mowing.  In general this means a full-mowing of the ROW in the month of July prior to seed set.
  • Keep a close eye on all your roadways and identify newly-occurring individual plants and very small new patches of these invasives.
  • Eliminate/eradicate those newly-occurring individual plants and very small new patches using methods appropriate for the species.
  • and, Sustain this program on a continuing basis. 
  • Unless resources are available to accomplish all of these priority control tasks, aggressive and more costly control of well-established populations should only be conducted if it can be justified for specific localities (e.g. a roadside population poses a definite threat to an adjacent high-quality natural area).  DO NOT spread established populations!


  • Our 2013 Roadside Survey Data for Southeastern Wisconsin is available on the EDDMapS website. Updated data for our 5 coastal counties was submitted to EddMapS in 2020.
  • 2018-2020 SEWISC EPA GLRI Project Final Report Collaboration to Halt the Spread of Invasive Species
  • Download a copy of the SEWISC ROW Invasive Species Management Plan
  • US Department of Transportation Federal Highway Administration's report featuring case studies of numerous invasive species, assessing how they are impacting transportation infrastructure and ways transportation agencies are responding: Invasive Species Impacts on Transportation Infrastructure    
  • While roadside right-of-way vegetation historically has been treated as a financial liability to fulfill main Department of Transportation functions, the information in this report provides evidence that roadside right-of-way vegetation is an asset: Florida DOT Report 2014   
  • Download the Transportation and Utility Rights-of-Way Best Management Practices for preventing the introduction and spread of invasive species.
  • View this webinar featuring representatives of the Illinois Department of Transportation and the New York State Department of Transportation who discuss challenges and opportunities they see from a DOT perspective. They share background information about DOTs involvement with invasives including training, staffing, some of their specific experiences managing invasive plants, the use of GIS in mapping and management and the importance of partnerships.  Please note that Wisconsin ROW management practices should follow Transportation and Utility Rights-of-Way Best Management Practices and not necessarily those used as examples by our neighboring state DOTs.