Aquatic Invasive Species Surveys

Overview Flowering rush (Butomus umbellatus) is an herbaceous, aquatic, perennial, rhizomatous monocot that is indigenous to portions of Europe and Asia and has been spreading cryptically across North America in the last century. Within Washington State, flowering rush is a Class A noxious weed that has been slowly spreading in portions of the Upper Columbia Basin. First listed as a Washington State noxious weed in 2009, flowering rush is considered a high priority weed species in the 2016 Land Operations Integrated Weed Management Plan. Flowering rush has been identified near Grand Coulee Dam in the Pend Oreille, Spokane, and Yakima River basins—meaning that downstream spread into the mainstem Columbia and adjacent tributary junctions is likely. Accordingly, flowering rush requires early detection and rapid eradication techniques to be effective in limiting future infestations, an approach recommended by the Washington State Noxious Weed Control Board and the Columbia Basin Cooperative Weed Management Area.

Our Role Working with our client’s staff, Four Peaks designed and implemented a study that mapped flowering rush populations and the environmental attributes and human lake and shoreline uses that influence aquatic invasive species colonization, spread, and persistence. Our field team performed boat-based visual assessments, underwater scoping, and vegetation sampling for 112 miles of Lake Roosevelt’s shoreline. The survey and subsequent report provided baseline monitoring data for assessing continued flowering rush spread, informed potential restoration and control strategies, and built a conceptual model of future habitats that are likely to be colonized by flowering rush.