Two California water agencies are seeking $500 million for a decade's worth of water that they say the federal government failed to deliver.

Two San Joaquin County water agencies say that since 1993 the U.S. Bureau of Reclamation has failed to deliver 37.5 million gallons a year from New Melones Dam, according to a complaint filed Tuesday in the Court of Federal Claims in Washington, D.C.

Much of the water was used to meet state and federal environmental regulations on salinity and federally protected fish in the Sacramento-San Joaquin Delta, according to the complaint.

Jeff McCracken, a spokesman for the U.S. Bureau of Reclamation, said he had not seen the lawsuit and declined to comment.

The Stockton East Water District and Central San Joaquin Water Conservation District supply water to more than 320,000 residents and 130,000 acres of San Joaquin County farmland. Stockton East spent $65 million to build tunnels and aqueducts to carry water it rarely receives.

"The system is bone dry most of the time," said Kevin Kauffman, general manager of Stockton East.

Nancie G. Marzulla, the attorney for the water districts, said the Bureau of Reclamation signed contracts in 1983 to provide the water, got California to agree to the deliveries and then "took the money and ran."

It is the third such case to emerge from California and Oregon in the Court of Federal Claims in recent years.

Farmers in the Klamath Basin along the California-Oregon border are seeking $100 million for water the Bureau of Reclamation used in 2001 to protect endangered suckers and threatened coho salmon.

In December, a judge awarded $26 million to farmers in Kern and Tulare Counties for water they lost in an effort in the early 1990s to save two rare fish. The Justice Department has not said whether it will appeal.

Critics have called the claims a stealth attack on the environment.

"The purpose of these suits is simply a backdoor attack on environmental laws," said Barry Nelson, a senior policy analyst with the National Resources Defense Council.