Reuters: The biggest seawater desalination plant in the Western Hemisphere, north of San Diego, can begin construction by year’s end after a six-year effort to win regulators’ approval, the developer said on Thursday. The San Diego Regional Water Quality Control Board voted unanimously on Wednesday to approve permit revisions for the $300 million facility, which will produce 50 million gallons of drinking water daily, enough for 110,000 households. That volume represents about 10 …