Thomas J. Graff, the Harvard-educated lawyer who was among the most influential environmentalists in California water policy during the last 30 years, died Thursday morning after a long battle with cancer. He was 65.

Graff, of Oakland, gave up a career at a prestigious San Francisco law firm to open the California office of the Environmental Defense Fund in the attic of a UC Berkeley fraternity house in 1971, helping the organization grow in the following decades into one of the most powerful voices on environmental issues ranging from climate change to oceans to water policy.

Friends and colleagues recalled Graff as exceptionally smart, interested in the views of others, a master negotiator and an energetic and forward thinker. He was devoted to his family and a good friend and mentor to many colleagues, friends said.

"He was one of the earliest environmentalists to advocate (that) if water could be marketed and moved more freely, it would be used more efficiently and we wouldn't need more dams," said Laura King Moon, assistant general manager for the State Water Contractors, a water industry group.

"You could be arguing violently with him one minute and hugging him goodbye a half-hour later. He was a lion in the water environmental movement over the last three decades," King Moon added.

Graff was born Jan. 20, 1944, in Honduras to German Jews who had fled Nazi Germany. He grew up in Syracuse, N.Y., and later attended Harvard College, Harvard Law School and the London School of Economics.

At the Environmental Defense Fund, he was a champion of the idea of using market forces to improve the environment by pushing for water marketing in California, and for plans to cap-and-trade sulfur dioxide emissions in the eastern states to combat acid rain.

"He was a great listener," recalled Spreck Rosekrans, a water policy analyst at the organization. "He always got along with people."

He was also a driving force behind the Central Valley Project Improvement Act, the 1992 law that reworked one of California's biggest water projects and perhaps the most important piece of environmental legislation in the career of Rep. George Miller, D-Martinez.

"One of Tom's great insights was in advocating for, and helping to develop, the water-marketing agreements that helped bring the business world and the urban water community on board," Miller said last year in a speech to Congress.

Graff was a leader in the political fights against construction of a Peripheral Canal around the Delta. When the Sierra Club was debating whether to accept a compromise that would allow the canal to be built, Graff argued that the canal would allow San Joaquin Valley farmers and Southern California to take too much water out of the estuary.

He sued the East Bay Municipal Utility District to block plans to tap into the American River, starting a 17-year legal battle over the health of the river and the Oakland-based district's contract rights to water. The utility eventually gave up its plans to build an intake on the American River and reached an agreement with environmentalists and Sacramento interests to move the intake downstream to the Sacramento River.

Graff is survived by his wife, Sharona Barzilay, the assistant head at the College Preparatory School of Oakland; sister Claudia Bial of Fort Lee, N.J.; daughter Samantha, son-in-law Miguel Helft, and grandchildren Avi and Rafael Helft of Oakland; son Benjamin of San Jose; and daughter Rebecca of Cambridge, Mass.

A private memorial is scheduled this weekend. A public service will be scheduled in the coming weeks.