Political agencies and nonprofits in the Central Valley say the Metropolitan District of Southern California’s $175 million purchase of four islands in the Sacramento-San Joaquin River Delta may cause significant environmental changes and sued to block the sale.

San Joaquin and Contra Costa counties, Central Delta Water Agency, Contra Costa County Water Agency and Food & Water Watch and the Planning and Conservation League sued the district on April 15 in San Joaquin County Superior Court, seeking a court order blocking Metropolitan District of Southern California’s purchase of 20,369 acres of property — including five delta islands and tracts — until an environmental review is satisfied.