Another legal challenge has been filed seeking to block the Metropolitan Water District of Southern California’s $175 million purchase of five islands in the heart of the Sacramento-San Joaquin Delta. This time, San Joaquin County and a group of Delta farmers allege that the pending sale represents a breach of contract.

Delta Wetlands Property, a subsidiary of Swiss financial services conglomerate Zurich Insurance Group, bought the islands 20 years ago with the aim of converting them into giant reservoirs that could store water in wet years and ship it to Southern California when supplies run low.