Los Angeles County and a host of local cities have launched a legal blitzkrieg against a new regulation that would force local governments to institute costly cleanup measures to keep all litter out of the Los Angeles River.

Four administrative appeals and one Los Angeles Superior Court lawsuit have been filed seeking to reverse a January decision by the Los Angeles Regional Water Quality Control Board that set forth the new regulation.

The regulation requires 52 governmental jurisdictions within the river’s watershed to install wire inserts in storm drains, increase street sweeping or take other measures to ensure that rain runoff does not carry litter into the river.

The board estimates that compliance could cost $300 million or more, but the cities put the cost north of $1 billion and contend that the board ignored cheaper alternatives. They also say the requirement to keep all trash out of the river is unrealistic.

“We have no problem reducing trash in the river, but when you make it a federal mandate of zero, we have a problem with it,” said Ed Schroder, director of public works for Signal Hill, which is leading a coalition of 18 cities opposing the regulation. “From a practical standpoint, nobody can really reach zero.”

The coalition is suggesting alternatives that would allow less-expensive regional solutions to the trash problem, like collecting trash in larger “retention basins,” which some storm drains empty into, rather than at the curbside or inside storm drains, Schroder said.

The regulation is the first major action under a federal consent decree reached with environmental groups.

The coalition, which includes cities from Irwindale to Vernon, filed an administrative appeal with the state Water Resources Control Board and a Superior Court lawsuit last month. The city of Los Angeles and the county also filed separate administrative appeals with the state board, while the cities of Monrovia and San Fernando filed a joint administrative appeal.

David Nahai, chairman of the regional board, said he is “extremely disappointed” by the appeals, which he has maintained are critical to restoring the river and Santa Monica Bay.

“We would much rather have received a cooperative response from the cities,” Nahai said. “I can’t really comprehend why they felt it was necessary to do this.”

The state board has already issued a letter indicating that, under law, it must review the new regulation anyway. But the cities said they wanted to keep all their legal options open.

Richard Montevideo, an attorney for the coalition, said that while cities plan to present their case to the state board, they also believe the regional board failed to follow the California Environmental Quality Act.

The act requires a detailed economic analysis of such regulations and their potential adverse environmental effects.