With months of contentious hearings ahead this summer, state and federal officials this week filed documents laying out their case that construction of two huge tunnels through the heart of the Sacramento-San Joaquin Delta would not harm north state water users.

In late July, the State Water Resources Control Board will begin a series of hearings to determine whether work can begin on the $15.5 billion tunnels project championed by Gov. Jerry Brown.

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.