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

Seattle District, USACE
Published July 22, 2024

U.S. Army Corps of Engineers’ (USACE) officials from Albeni Falls Dam will be performing aquatic herbicide treatments at five (5) separate USACE owned locations on Lake Pend Oreille, totaling a minimum of 28 acres and a maximum of 60 acres, to manage the invasive weed, flowering rush.

These five treatment areas fall within the following locations: Riley Creek, Morton Slough, Oden Bay, Pack River Delta, and the Clark Fork Drift Yard. Please reference the map below for treatment locations. For real time treatment zone updates, please visit the following Idaho State Department of Agriculture (ISDA) link: <https://invasivespecies.idaho.gov/treatment-plans> and select “Treatment Map”. USACE will be treating flowering rush in these five 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.

The flowering rush work is expected to occur between August 5-16, 2024. If weather delays interrupt applications during this period, then August 19-23, 2024, will serve as an alternate treatment window. 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. All treatment plots are located at least 600 feet from all water rights and public intake points.

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

Separate from submerged flowering rush treatments, USACE will be undertaking treatments of emergent noxious weeds on the debris control booms (up to 9,000 linear feet) at the Clark Fork Drift Yard using no more than 1.5 gallons of glyphosate (AquaNeat). Only booms with vegetation present will receive spot treatments on individual plants. The Clark Fork Drift Yard debris control boom treatments will take place sometime in the August 5-31, 2024 timeframe.

For more information, contact Andrew Huddleston 208-437-3133, extension 7213 (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, extension 7225 (Taylor.M.Johnson@usace.army.mil).

As required by USACE-NWS’s EPA IPDES permit: Department of Environmental Quality’s (DEQ) regional Idaho State IPDES Compliance Officer, Mathew Colling: (208) 666-4639, DEQ’s IPDES Pesticide General Permit, and Application of Pesticides (IDG870000).


Contact
Andrew Huddleston
208-437-3133
Andrew.J.Huddleston@usace.army.mil

Release no. 24-022