In a failed effort to protect endangered fish, the federal government decided without proper study to default to restricting the giant pumps at the bottom of the Sacramento-San Joaquin Delta.

So argues a lawsuit filed Friday at the U.S. District Court in Sacramento by a powerful consortium of water agencies. They’re hoping for a larger share of Delta water. It’s the latest salvo in a political and legal dispute over how to manage the competing demands on the fragile estuary.