Are Your Ponds Serving their Water Quality Function? 

12:00 PM | Thursday, June 1, 2023

Session Description

Stormwater ponds and wetlands across a wide variety of characteristics (e.g., watershed history, age, size, depth, aquatic vegetation) are used to treat stormwater to remove a significant portion of sediment and associated pollutants in runoff (e.g., phosphorus, nitrogen, hydrocarbons, and metals) prior to the runoff being released downstream. An important contemporary management issue is that some stormwater ponds appear to be less effective than expected or originally intended in phosphorus retention, a key function of these stormwater best management practices (BMPs) in urban environments. There is recent evidence that many old stormwater ponds are releasing phosphorus from bottom sediments at high rates and likely exporting phosphorus to downstream surface water bodies. The potential for phosphorus re-release from accumulated sediments in ponds and factors related to climate, watershed, pond characteristics that regulate phosphorus release or burial are important in controlling phosphorus dynamics in ponds. Retention of phosphorus is critical because phosphate, a dissolved form of phosphorus, sustains algal and cyanobacteria growth and causes a wide range of water quality impairments in the ponds and downstream waters including algal blooms, excess floating plants, taste, and odor problems.

Learning Objectives

A Pond Assessment Tool, was developed to identify and evaluate ponds at risk for poor phosphorus water quality and export of phosphorus to receiving water bodies. It results from data analysis of 230 water bodies and detailed water quality and sediment analysis of 20 ponds, which formed the basis of the Pond Assessment Tool tool with statistical analysis of field data and regression models for predicting pond TP, pond anoxia, and sediment release. 

Recommendations for stormwater pond maintenance and wetland management based on project results and data synthesis of construction and maintenance costs and runoff storage/settling alternatives.

John S. Gulliver is a professor emeritus in the Department of Civil, Environmental and Geo- Engineering and a resident fellow at the Institute on the Environment. Gulliver has taught courses in fluid mechanics, environmental mass transport, and urban hydrology and water quality.  Poornima Natarajan is a Research Associate at the St. Anthony Falls Laboratory, with research interests focused on stormwater management and treatment She received her Ph. D. from the University of Maryland in 2012.

Since 2016, Dr. Gulliver, Dr. Natarajan and co-investigators have been studying phosphorus release from pond sediments resulting from low dissolved oxygen concentrations in the bottom of the pond caused by pond thermal and chemical stratification. They first identified shallow stratification and low bottom-water dissolved oxygen as the cause of high phosphorus concentration in some ponds and began a field campaign to identify the ponds that were releasing phosphorus from the sediments and develop a rationale for these events.   After multiple years of pond in situ measurements of temperature, dissolved oxygen and conductivity profiles in the ponds; sediment characterization and release rate studies and field weather measurements in 21 ponds, they used the information to develop a Pond Assessment Tool to assess the likelihood of low dissolved oxygen concentration, high phosphorus concentration in the pond, and phosphorus release from the sediments in Minnesota ponds.   They also developed a numerical model of pond stratification and water chemistry, linked with a three-dimensional wind model to investigate the efficacy of six pond phosphorus remediation techniques.

Access Information

Once you complete and submit the form below, your confirmation will be emailed to you which will include a LINK to access the virtual webinar space where you'll be able to join the live session on Thursday, June 1, 2023, beginning at 11:55am Central. Please keep your confirmation in a safe place - if you misplace it, check here or email [email protected] to resend your confirmation. Please note that this session will be presented through Zoom and a Zoom download will be required for access.

Registration and Fees

The registration fee is free for CEAM members and $10 for non-members. Participants may also renew their annual CEAM Membership at this time and immediately receive the webinar for free as a member. 

CEU Certificates

A maximum of .100 CEU can be obtained for attending the CEAM Webinar. Once you have submitted the post-webinar evaluation and provided your name and email address, we will have record of your attendance and you will be emailed your unique CEU certificate form in the weeks following the webinar. 

Payment Details

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