MEDIA RELEASE

California Water Service Group (NYSE: CWT) announced today that its Hawaii subsidiary, Hawaii Water Service, has entered into an agreement with Keauhou Community Services, Inc. (KCSI) to operate and maintain a wastewater collection and treatment system serving 1,500 residential, hotel, and commercial customers in Keauhou on the island of Hawaii. The system also serves the Keauhou Bay Facility and Kahaluu Beach Park and provides effluent to the Kona Country Club, Inc. for golf course irrigation.

“KCSI has an important role in the Keauhou community to be a good steward of the land and nurture Native Hawaiian culture. We are honored to be selected to provide wastewater collection and treatment services,” said Hawaii Water Service General Manager Tony Carrasco. “We look forward to providing the quality, service, and value our customers have come to expect.”

Hawaii Water Service provides water and wastewater service to many communities located on Maui and Big Island of Hawaii. Hawaii Water Service is a wholly owned subsidiary of California Water Service Group, which also includes California Water Service, Washington Water Service, and New Mexico Water Service. Together, these companies provide regulated and non-regulated utility service to approximately 2 million people in more than 100 California, Washington, New Mexico, and Hawaii communities. Group’s common stock trades on the New York Stock Exchange under the symbol “CWT.” Additional information is available online at www.calwatergroup.com