Travelers hoping for a relaxing lake vacation likely already know about invasive zebra mussels and quagga mussels that have overrun many popular lakeside destinations. Unfortunately, California faces a similar threat from another invasive species: Golden mussels. The mollusks have been detected in the Sacramento–San Joaquin Delta, and they have already spread to two Southern California lakes near Los Angeles: Silverwood Lake and Pyramid Lake. The likelihood of the mussels spreading from Silverwood Lake to connected Lake Perris is high, and the spread will not stop there. Because the Sacramento-San Joaquin Delta is a major supplier of fresh water to California, the mussels threaten to jeopardize the supply for nearly two-thirds of the state's population.