R/M recently partnered with the City of Columbus to coordinate a water quality trade with Nasco, a neighboring industrial point source located within the Rock River Basin.

Nasco is a Life Sciences education supply company that specializes in the development of frogs and other research-grade specimens for testing. The company’s hundreds of frog tanks contain about 150 gallons of water each and drain directly to the storm sewer leading into the Rock River. Prior to their agreement with the City of Columbus, Nasco was having trouble meeting their Rock River phosphorus TMDL (total maximum daily load) goals.



Phosphorus has long been recognized as the controlling factor in aquatic plant and algae growth in Wisconsin lakes and streams. Minor increases in phosphorus can result in significant aquatic plant and algae growth, which in turn can negatively impact recreational use, property values, and public health.


In order to protect our waterways and meet phosphorus TMDL goals, the state of Wisconsin allows point sources (piped wastes that release liquid effluent to lakes and rivers) to participate in water quality trading, a practice that helps point sources offset their pollutant loading by trading with other point or nonpoint sources in the watershed that are exceeding their phosphorus reduction goals.



The R/M team worked with the City to navigate a water quality trade that gave Nasco the phosphorus credits necessary to comply with their TMDL goals and provided the City with additional financial resources that can be used to work towards their other non-TMDL phosphorus permit limits. Most importantly, this agreement helped both the City and Nasco improve the health of the Rock River watershed.


For more information on water quality trading and TMDL compliance, please contact Dave Arnott today!

About the Author

David W. Arnott

David W. Arnott, P.E.
Team Leader/Senior Project Manager

Dave has extensive experience in the planning, design, and construction project management of wastewater treatment facility renovation and upgrade projects. Areas of expertise include treatment processes, hydraulics, mechanical equipment, and wastewater disinfection. He also has experience in sanitary and water pumping station design and sanitary sewer wet weather facilities.

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