Exhibit 99.1

Southwest Water Names Mark A. Swatek Chief Executive Officer

    LOS ANGELES--(BUSINESS WIRE)--April 18, 2006--Southwest Water
Company (NASDAQ:SWWC) announced that its board of directors has
selected Mark A. Swatek chief executive officer. Swatek, 53, will join
the company in mid-May, succeeding Anton C. Garnier, chairman and
chief executive officer, who has led the company for 38 years.
    "Mark Swatek brings a strong operating track record and more than
28 years of experience leading and managing companies in the water and
wastewater industry," Garnier said. "He has a proven record of driving
both top-line growth and profitability. I am extremely pleased to have
Mark join the Southwest Water team and lead the company in its next
stage of growth and development."
    Commenting on his new position, Swatek said, "In evaluating the
opportunity with Southwest Water, I found a company with a solid track
record of growth and performance. Southwest Water, under Tony
Garnier's leadership, has earned a reputation for providing reliable,
quality service to its clients. I look forward to leading this
company's talented management team to continue to capitalize on the
tremendous growth opportunities in the water and wastewater industry."
    Swatek was chosen after the board conducted a nation-wide search
for a candidate with strong leadership abilities and a thorough
knowledge of the water utility industry. He most recently was
president of MWH State and Local Government operations, the largest
operating division of MWH Global, a $1 billion worldwide engineering
consulting and construction firm that specializes in serving the
municipal water and wastewater market. In this capacity, he managed
the 1000 person, $350 million revenue per year US municipal operations
which provides water/wastewater engineering, program management, and
facility design-build activities for city, county, and state
governments. Prior to this position, Swatek was President of MWH
Constructors, the design-build construction subsidiary of MWH, where
he was responsible for rapid top and bottom line growth of the
subsidiary, creating one of the top integrated design-build-operate
companies focusing on water/wastewater facilities in the US and UK.
    Swatek earned bachelor of science and master of science degrees in
civil engineering from Purdue University, and is a graduate of the
Harvard Business School Advanced Management Program. He is a
registered professional engineer and licensed general contractor in
multiple states. Swatek also has served as a director on a number of
boards of engineering and contractor companies.

    Southwest Water Company provides a broad range of services
including water production, treatment and distribution; wastewater
collection and treatment; utility billing and collection; utility
infrastructure construction management; and public works services. The
company owns regulated public utilities and also serves cities,
utility districts and private companies under contract. More than two
million people from coast to coast depend on Southwest Water for
high-quality, reliable service. Additional information may be found on
the company's Web site: www.swwc.com.

    CONTACT: Southwest Water Company
             DeLise Keim, 213-929-1846
             www.swwc.com
             or
             PondelWilkinson Inc.
             Robert Jaffe, 310-279-5969
             www.pondel.com