A portion of the Delta is now owned by a powerful water agency from Los Angeles.

The Metropolitan Water District of Southern California said Monday that it has completed its purchase of five islands in the Sacramento-San Joaquin Delta, a $175-million deal that has aroused suspicion about a “water grab.”

Metropolitan announced the completion of the purchase in a two-paragraph memo to board members from the agency’s general counsel. The deal was finalized three days after the state Supreme Court turned aside legal efforts by San Joaquin County officials and others to block the acquisition.