Quagga and zebra mussels have spread rapidly across the country since they were first discovered in the late 1980s and, according to U.S. Army Corps of Engineers officials, have spread to every major river basin in the U.S. except the Columbia River Basin in the northwest. The mussels typically are spread by recreational watercraft such as boats, canoes, and Jet Skis that have been in infested waters. Once established in a water body, the mussel species are extremely difficult to eradicate because they have no natural predators in the U.S. and rapidly reproduce.
GAO was asked to examine efforts the Corps has undertaken to prevent the spread of aquatic invasive species into the Columbia River Basin by recreational watercrafts. This report [PDF, 3.24 MB] provides information on the Corps' Watercraft Inspection and Decontamination Program and its role in helping to prevent the introduction or spread of quagga and zebra mussels—the aquatic invasive species of greatest concern to the Corps—as well as program challenges and opportunities for improvement.