Press Release

Cal Water President & CEO to Speak at International Water Conference

SAN JOSE, Calif.--(BUSINESS WIRE)--Sept. 12, 2007--California Water Service Group (NYSE:CWT) President and Chief Executive Officer Peter C. Nelson will deliver an update on the operations of the Company and regulatory changes at the Stanford Group Company's 2007 International Water Conference. The presentation, part of a panel discussion called "Water Utilities - Trends and Transitions," will be held at Intercontinental The Barclay New York in New York City on Tuesday, Sept. 18, 2007, at 11 a.m. EDT.

California Water Service Group is the parent company of California Water Service Company, Washington Water Service Company, New Mexico Water Service Company, Hawaii Water Service Company, Inc., and CWS Utility Services. The subsidiaries provide regulated and non-regulated water service to over 2 million people in 100 communities. The Company's common stock trades on the New York Stock Exchange under the symbol "CWT." Additional information about the company is available online at www.calwatergroup.com.

CONTACT: California Water Service Group
Shannon Dean, 310-257-1435 (media)
Martin Kropelnicki, 408-367-8200 (analysts)

SOURCE: California Water Service Group