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Center for Transportation Studies Webinar

Maintaining Stormwater Ponds for Improved Phosphorus Retention

Stormwater ponds play an important role in protecting water quality, but phosphorus trapped in pond sediments can be released back into the water when low-oxygen conditions develop. This webinar will highlight University of Minnesota research examining how stormwater pond management practices can help reduce phosphorus pollution and maintain pond treatment capacity.

CTS emeritus scholar John Gulliver will share findings from a research project that used field measurements and the MinPond model to evaluate management approaches across six ponds. His presentation will explore how effective strategies such as intensive street sweeping, chemical treatment of sediments, and bubble aeration are in reducing phosphorus export from stormwater ponds.

DATE & TIME: Friday, November 6, 2026, 12:00 - 1:30pm US Central time

This webinar is Online only.

Registration: This webinar is free, but registration is required. Visit the event web page to register and for more information. 

Minnesota Stormwater Seminar Series

Stormwater Pond Management: Sizing Pretreatment for Cost Effective Maintenance and Evaluating Remediation Methods

Please join us in person or online on November 12, 2026 for a the next Minnesota Stormwater Seminar Series event - a monthly experience featuring national, state, and local experts on stormwater and green infrastructure.

Speakers & Panelists:

• Research Spotlight Speaker #1: Dr. Poornima Natarajan, Researcher at St. Anthony Falls Laboratory, University of Minnesota
• Research Spotlight Speaker #2: Dr. Grace Wilson, Research Assistant Professor, Department of Bioproducts and Biosystems Engineering, University of Minnesota.
• Panelist: Cathy Abene, Principal Civil Engineer, UMN Office of Sustainability
• Panelist: Gareth Becker, Senior Civil Specialist, Barr Engineering
• Panelist: Patrick Sejkora, Water Resources Engineer, City of Eden Prairie

Abstract 1: As stormwater ponds age and accumulate phosphorus-rich sediments, their ability to retain phosphorus can decline. Reducing sediment phosphorus release from ponds is a major stormwater management challenge because phosphorus is the primary limiting nutrient that drives algal blooms and excessive floating vegetation. The Minnesota Stormwater Research Council funded a project to investigate the overall effectiveness and effectiveness over time of three promising pond remediation techniques: alum treatment, iron amendment of sediments, and enhanced watershed street sweeping. We collected water quality data and performed detailed sediment phosphorus chemistry analysis at several treated ponds over multiple years to determine the impact on sediment phosphorus release and assess the duration a given remediation technique would be effective. The study revealed variations in performance and longevity across the three methods, providing information that can help communities to select cost-effective maintenance strategies for reducing phosphorus export from ponds. 

Abstract 2: Passive stormwater treatment systems often have pretreatment requirements, but the sizing and comparisons between pretreatment options are not well described. This paper provides a generalized methodology for practitioners for selection and sizing of pretreatment options that uses economic optimization. The pretreatment options included here are: forebays in wet pond systems, deep sump manholes, and shallow catch basin sumps. Maintenance records from previous research on deep sumps, shallow catch basins, and pond clean-out activities were used to develop this methodology. Some of the data from these records were then used to aid in the development of a pond sediment-settling model that predicted the effect a pond forebay on pond trapping efficiency. This information was then included in a simple economic optimization, and presents a simple means to help practitioners choose the optimal size including economic considerations. This method is shown for three watersheds representing residential watersheds in the Twin Cities Metropolitan Region in Minnesota. While the development of the methodology to aid practitioners in the selection of appropriate pretreatment systems was the primary focus of the research, results from the data analyzed also point to an optimal pond forebay size for those watersheds modeled. There appeared to be a similar trend across all systems modeled to have an optimal pretreatment of a forebay that is sized for about 8% of the treatment system wet surface area. 

DATE & TIME: Thursday, November 12, 2026, 10a - 12p US Central

In-person: St. Anthony Falls Laboratory Auditorium (2 Third Ave SE, Minneapolis, MN). THERE IS NO PARKING AVAILABLE AT SAFL. We recommend you consider biking (bike racks available at SAFL), mass transit, or parking in the 212 SE 2nd Ave parking garage, free or metered parking along nearby side streets (3rd Ave, Main Street, etc.) and give yourself about 10-15 minutes to walk down to SAFL (2 Third Ave SE).

Online: https://z.umn.edu/mn-stormwater-seminar-series (active 10 minutes prior)

Registration: Click here to learn more and Register

About the MN Stormwater Seminar Series:

The Minnesota Stormwater Seminar Series is a monthly program featuring national, state, and local experts in unique discussion panels that share their research, knowledge, and innovations in stormwater and green infrastructure. This seminar series is a program of the University of Minnesota's St. Anthony Falls Laboratory and Water Resources Center. The seminar is supported by the Minnesota Stormwater Research Council, the Clean Water Land and Legacy Amendment by appropriation through the Clean Water Fund, and in kind by the Cold Climate Stormwater Center of Excellence, which is funded by the U.S. Environmental Protection Agency and co-directed by the University of New Hampshire and the University of Minnesota, in partnership with the National Municipal Stormwater Alliance.

See the full schedule here or visit our YouTube Channel for all recordings.

Past Minnesota Stormwater Seminars (YouTube Channel):

• Real-Time Control For Enhanced Urban Stream Health: Promising or Over-Promising? featuring Jon Hathaway and local experts.
• A Broader Look at Low Impact Development featuring Liv Haselbach.
• Data-Driven, Unbiased Metrics to Evaluate BMP Water Quality and Hydrologic Mitigation Performance featuring Elizabeth Fassman-Beck and local experts.
• Engineered Amendments for Climate-Resilient Green Infrastructure featuring Sanjay Mohanty, UCLA, and local experts.
• Adaptive Level Control Systems – Research on Maximizing Stormwater Pond Functionality featuring Cory Anderson, Sarah Stratton, and local experts.
• Can stormwater pond sediment be managed as a valuable resource instead of a costly waste? featuring Dr. Francine Kelly-Hooper, GHD, and local experts.
• Minnesota Watersheds: Uniquely Equipped to Address Water Resource Challenges featuring Louis Smith, Smith Partners, and local experts.
• The Green Stormwater Revolution: What Have We Learned and What's Next? featuring Rob Traver, Villanova University, and local experts.
• Stormwater reduction and pollutant sourcing from urban trees featuring Xue Feng (UMN), Diana Karwan (UMN), and local experts.
• Addressing the challenge of water-soluble emerging contaminants in green stormwater infrastructure featuring Greg LeFevre, University of Iowa, and local experts.
• Urban Flash Flood Detection with Low-Cost IoT Sensor Networks featuring Bill Selbig, USGS, and local experts.
• Enhanced Street Sweeping: America's First Line of Defense in the Abatement of Urban Stormwater Pollution featuring Roger Sutherland, Cascade Water Resources, LLC, and local experts.
• Performance and Maintenance of Sand Filters Amended to Retain Phosphate featuring John S. Gulliver, St. Anthony Falls Lab & University of MN, and local experts.
• Managing Stormwater Ponds for Optimal Function: Characterizing Phosphorus and HAB Export, Plus a New Tool for Prioritizing Maintenance Needs featuring Katie Hembre (Stantec), Dr. Poornima Natarajan (UMN SAFL), and local experts.
• Using Winter Chloride Management to Reduce Impacts of Winter Maintenance Operations featuring Laura Fay, Montana State University, and local experts.
• Turning tight spaces into big solutions: testing a high-volume stormwater filter at Rosland Park featuring Andy McCabe, Barr Engineering, Erica Sniegowski, Nine Mile Creek Watershed District, and local experts.
• Extreme Weather Impacts Across the Water Sector Sunny Wescott, Cybersecurity and Infrastructure Security Agency (CISA) Chief Meteorologist and Federal Emergency Response Official and local experts.
• Assessment of urban stormwater chloride and its impact on surface water trends featuring Dr. Ben Janke, Dr. Jacques Finlay, and local experts.
• Funding and technical assistance for stormwater management and green infrastructure featuring Robyn DeYoung, US EPA; Travis Ostrom, US EPA, and local experts.
• Moving towards multi-functional stormwater management systems featuring Lauren McPhillips, Penn State University, and local experts.
• Watershed-scale effectiveness of green stormwater infrastructure featuring Aditi Bhaskar, University of Colorado Boulder, and local experts.
• Emerging policy issues that may influence future stormwater management efforts featuring Chris Kloss, U.S. EPA, and local experts