A mound of harvested Eurasian watermilfoil piles up Aug. 24, 2015, near the Tahoe Keys in South Lake Tahoe, California. Residents of the private community pay to remove the aquatic invasive species because it can wrap around propellers and clog up filters on watercraft. The U.S. Army Corps of Engineers Sacramento District works with local partners to combat aquatic invasive species because they pose a major threat to ecosystem health in the Lake Tahoe Basin by degrading water quality and destroying important habitat to native species.