The nation’s largest municipal water provider attempted to illegally divert water toward Southern California cities by buying up and throttling water use on thousands of acres of farmland, according to a lawsuit filed last week in Riverside County Superior Court. The suit was brought by the Palo Verde Irrigation District, which serves parts of Imperial County and Riverside County. It accuses the Metropolitan Water District of Southern California of violating a 2004 agreement that paid farmers not to grow crops on their land, freeing up water for thirsty coastal cities serviced by Metropolitan.