 In December 2009 PSE sold the reservoir to the Cascade Water Alliance, a municipal corporation whose members are five King County cities (Bellevue, Issaquah, Kirkland, Redmond, and Tukwila) and two water and sewer districts (Sammamish Plateau Water and Sewer District, and the Skyway Water and Sewer District).Cascade provides drinking water to more than 350,000 residents and more than 20,000 businesses.It plans to eventually use Lake Tapps as a municipal water supply source for customers of its members.