Press Release

California Water Service Group Schedules Second Quarter 2007 Earnings Announcement and Teleconference

SAN JOSE, Calif.--(BUSINESS WIRE)--July 18, 2007--California Water Service Group (NYSE: CWT) today announced that its second quarter earnings results will be released after the market-close on Wednesday, August 1, 2007, and its teleconference will be held at 11 a.m. EDT on Thursday, August 2, 2007.

All stockholders and interested investors are invited to listen to the teleconference. The 2007 second quarter conference call may be accessed by dialing 1-866-253-5757 and keying in ID# 1100221. A replay of the call will be available from 2:00 p.m. EDT on Thursday, August 2, 2007, through October 1, 2007, at 888-266-2081, ID# 1100221. The call, which will be hosted by President and Chief Executive Officer Peter C. Nelson and Vice President and Chief Financial Officer Martin A. Kropelnicki, will also be webcast under the investor relations tab at www.calwatergroup.com.

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. Together these companies provide regulated and non-regulated water service to more than 2 million people in 100 California, Washington, New Mexico and Hawaii communities. Group's common stock trades on the New York Stock Exchange under the symbol "CWT."

CONTACT: California Water Service Group
Shannon Dean, 310-257-1435


SOURCE: California Water Service Group