U.S. Army Corps of Engineers to treat invasive flowering rush on Lake Pend Oreille

U.S. Army Corps of Engineers, Seattle District
Published July 19, 2023
Updated: July 19, 2023

U.S. Army Corps of Engineers (USACE) officials at Albeni Falls Dam will be performing aquatic herbicide treatments at six separate USACE owned locations on Lake Pend Oreille, totaling 26 acres, to manage invasive weed, flowering rush. These six locations and treatment plot acres include the following locations: Riley Creek (3 acres), Morton Slough (11 acres), Oden Bay East (4 acres), Pack River Delta (3 acres), Clark Fork Drift Yard (4 acres), and Clark Fork River Delta (1 acre). Please reference the map below for treatment locations. USACE will be treating flowering rush in these six small treatment plots with U.S. Environmental Protection Agency (EPA) and Idaho State Department of Agriculture (ISDA) approved herbicides: diquat dibromide (Reward) and diquat dibromide + endothall (Aquastrike), at application rates and concentrations allowed on the labels. Additionally, USACE will be undertaking treatments of noxious weeds on the debris control booms (up to 9,000 linear feet) at the Clark Fork Drift Yard using glyphosate (Rodeo).

The flowering rush work is expected to occur between August 8-18. If weather delays interrupt applications during this period, then August 21-25 will serve as an alternate treatment window. The Clark Fork Drift Yard debris control boom treatments using Rodeo will take place August 8-31. There are no fishing or swimming restrictions for any chemicals in the treated plots, after the herbicide applications; however, domestic animals or livestock should not consume water from the treated plots for 24 hours after application. Additionally, there is a 3-day restriction on using the water from the treated plots for drinking or irrigating landscape, and a 5-day restriction on irrigating food crops.

   The USACE will ensure notices are posted on the shorelines of plots being treated 48 hours prior to treatment.

For more information, contact Andrew Huddleston 208-437-3133 (Andrew.J.Huddleston@usace.army.mil), U.S. Army Corps of Engineers Albeni Falls Dam, 2376 East Highway 2, Oldtown, ID 83822, or Taylor Johnson 208-437-3133 (Taylor.M.Johnson@usace.army.mil).

As required by USACE-NWS’s EPA IPDES permit: Department of Environmental Quality’s (DEQ) regional Idaho State Emergency Response Commissions Contact (Sarah Cerda, DEQ SERC): 208-258-6524 and DEQ’s IPDES Pesticide General Permit from the (SERC) Application of Pesticides (IDG870000).

Andrew Huddleston

Release no. 23-023