Cons Sci Seminar - 11/21/25

November 21, 2025

12:00-1:00pm

In person (preferred): 335 Borlaug Hall, St. Paul Campus, UMN

Remote access: https://umn.zoom.us/j/91587399054

A field study of recreational powerboat hydrodynamics and their impacts on the water column and lakebed

Jeff Marr and Andy Riesgraf

St. Anthony Fall Laboratory, University of Minnesota

Abstract

The increase in powerboat popularity, along with increasing boat size, horsepower, and newer wake-enhancing technologies, has led to increasing concerns for the health of lakes and reservoirs. More specifically, wakeboats and the mode in which they operate during wakesurfing is a topic of intense interest. In this presentation, we will discuss a field-based research study that focused on impacts within the water column and at the lakebed as different powerboat types travel in their typical modes of operation. The objectives of this study were to: 1) identify and characterize the hydrodynamic phenomena created by a recreational powerboat in motion; 2) investigate the water column velocities and depth of penetration of the bow, stern, and transverse waves and their potential to resuspend sediment; 3) investigate the propeller wash velocity, depth of penetration, and its potential to resuspend sediment; 4) capture underwater and aerial video of the hydrodynamic phenomena and any subsequent impacts. This presentation will provide a brief overview of the study design, data collection approaches, findings, and boating recommendations as they related to depth of operation to minimizing impacts to the lakebed and water quality.

Biosketches

Jeff Marr: Jeff Marr is the Associate Director of Engineering and Facilities at the St. Anthony Falls Laboratory. Marr manages SAFL’s Applied Research and Engineering Team, which has ongoing work for public and private organizations in the fields of boat-

generated waves, urban stormwater, hydraulic modeling, wind and water power, river engineering and restoration, and technology development for field monitoring. Marr is a licensed civil engineer specializing in hydraulics and sediment transport. His research interests include water hydraulics, river engineering and restoration, sediment transport dynamics, and hydropower. Marr is also an affiliated researcher with the University of Minnesota Center for Transportation Studies.

Andy Riesgraf: Andy joined the University of Minnesota in 2016 as a Research Scientist with the Minnesota Aquatic Invasive Species Center (MAISRC), where he studied deterrent methods to stop the upstream migration of invasive carp in the Mississippi River. In 2020, he joined SAFL’s Applied Research and Engineering team as a Research Scientist. Andy specializes in designing and conducting field studies on lakes and rivers, with technical expertise in the deployment of data acquisition systems. His research interests include lake and river water quality, boat-generated waves and propeller wash impacts, tracking fish and aquatic mammals, and aquatic invasive species prevention/management.