23-037 Corps to treat Lake Wallula to control invasive flowering rush

Published June 28, 2023

WALLA WALLA, WA– The U.S. Army Corps of Engineers Walla Walla District will be performing up to five five-acre treatments in Lake Wallula, the McNary reservoir near the Tri-Cities, Washington, with herbicide, Diquat Dibromide, at an application rate of two gallons per surface acre. This effort is to control the invasive aquatic plant species flowering rush.

The work is expected to begin between July 16 and 20 and may continue through Sept. 1 if necessary. There are no fishing or swimming restrictions for the area of treated water after the herbicide application, however animals should not consume water from the area of treated water for 24 hours after application. Additionally, there is a three-day restriction on using the water from the area of treatment for drinking or irrigate landscape and a five-day restriction on irrigating food crops.

USACE will post notices on the shorelines of areas being treated 48 hours prior to treatment.

For more information. Contact Damian Walter at 509-527-7136 or Damian.J.Walter@usace.army.mil. Or, contact Brett Forge at 509-543-6073 or Brett.A.Forge@usace.army.mil.

The Washington Department of Ecology’s regional 24-hour emergency number is 1-306-407-6600 and Environmental Compliance Agency’s National Pollutant Discharge Elimination System compliance number is 1-206-553-1846.


Release no. 23-039