Brownstein already handles water cases in addition to real estate, lobbying, litigation, corporate law and gaming cases. Jim Lochhead, a Brownstein lawyer who specializes in water, said Thursday that the merger will allow the combined firm to handle cases across the West at all stages, from arguing for water rights in court to securing permits from regulators.

Lochhead said water will become the most important natural resource in the West over the next 20 to 30 years because of climate change and population growth. He thinks utilities and private industry will increasingly be looking for new ways to provide it and willing to go farther to get it, such as recycling water or converting sea water to drinking water.

"Those kinds of projects and that kind of thinking is really going to require a broadbased approach," Lochhead said.

He said the firm would not be able to represent any cases in which California and Colorado water interests are in direct opposition. But increasingly he thinks complicated water disputes will be worked out by negotiating, as happened recently among upper and lower basin states who depend on water from the Colorado River.

Brownstein's current clients include the Denver suburb of Aurora, the Idaho Power Co. and real estate developers in New Mexico and Colorado.

Hatch & Parent represents the San Diego Water Authority, the cities of Fresno and Oxnard and the South Tahoe Public Utility District.