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USACE to begin applying safe tracer dye to sites along Connecticut River as part of invasive plant research

Published July 31, 2023

The U.S. Army Corps of Engineers, New England District announced today that USACE and the Engineer Research and Development Center (ERDC) will begin applying Rhodamine WT (RWT) tracer dye in August at multiple sites along the lower Connecticut River to better understand water exchange dynamics as part of a research project.

USACE is working in partnership with the Lower Connecticut River Valley Council of Governments and the Connecticut Agricultural Experiment Station to conduct a research and demonstration project to better understand and control the invasive aquatic plant hydrilla (hydrilla verticillata) that is currently spreading throughout the lower Connecticut River and its tributaries. To control and eradicate hydrilla, USACE and ERDC plan to treat several sites on the river during the summer of 2024.

The RWT tracer dye application will occur over the next few months at four sites to inform the development of individual herbicide treatment plans for control of the hydrilla. Primary site locations in Connecticut to receive the RWT dye in the coming months are Keeney Cove in Glastonbury, Chapman Pond in East Haddam, Chester Boat Basin in Chester, and Selden Cove in Lyme. Alternate sites have been identified and will be used, if necessary. These alternate sites are Deep River in Deep River, Mattabesset River in Middletown, and Portland Boat Works in Portland.

RWT dye is a fluorescent, xanthene dye that has been safely used for decades for water tracing to quantify time of travel in dynamic waters. The dye has no significant effects on aquatic organisms and has been proven by ERDC to be safe for use during these types of studies. There will be impacts to the color of the water at the sites and surrounding areas as the dye is bright red in color, but these are expected to be minimal and short term as the dye will dilute and dissipate with the flow and tides of the river. 

The dye is scheduled to be applied at the four primary test sites weekdays between August 7 through Sept. 15, 2023, with a proposed alternate end date of Sept. 22, 2023. This schedule is subject to change. The most up to date RWT tracer dye schedule and maps of the primary site locations can be found on the USACE project website at https://www.nae.usace.army.mil/Missions/Projects-Topics/Connecticut-River-Hydrilla/.

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Bryan Purtell

Release no. 23-026