 Even earlier than the collections in Massachusetts and New York, a population of U. inflata was located in Horseshoe Lake in Kitsap County, Washington in 1980. Since then, further specimens of U. inflata have been recorded from other Puget Sound area lakes in Kitsap, Mason, Pierce, and Thurston counties. One population has even been recorded from the more southern Silver Lake in Cowlitz County. Information on this species in Washington State provided by the state's Department of Ecology includes a statement that U. inflata's presence in Horseshoe Lake was "probably the result of a discarded aquarium." Washington's Department of Ecology also indicates that in the areas where it occurs, U. inflata forms dense floating mats, becoming a nuisance for recreational activities. Residents of Lake Limerick, which has extensive populations of U. inflata, spend thousands of dollars each summer to rid their lake of the dense, weedy mats. A variety of control methods have been used to control the weed, including a sonar treatment, biocontrol utilizing grass carp, and manual extraction. Washington considers this species to be problematic but has not classified it as a noxious weed. Instead, it is on a monitor list of wetland and aquatic species under quarantine, meaning that it is prohibited to sell this species and it may be included on the state's noxious weed list in the future.
