Rep. Jeff Denham, one of the nation’s most vulnerable Republicans, is trying desperately to shut down a state water plan that’s widely disliked in his district. But nothing has worked so far. One thing could: Yet another lawsuit between the Department of Justice and the state of California over the issue. Denham first tried to include a provision in a congressional budget bill in July that would prevent a federal reservoir, called New Melones, from using federal dollars to participate in the plan, which would direct greater amounts of water out of his district’s water resources and into the ocean, purportedly to help salmon populations.