MONTEREY, Calif. — Gripped by drought, communities along California’s coast are exploring innovations and investments to ensure residents have access to drinking water. But desalinating seawater, one proposed solution, has provoked heated debate, as some environmentalists say the process is inefficient, expensive and unneeded. The California Coastal Commission next month will decide whether to approve a private company’s application to build a $1.4 billion seawater desalination facility in Huntington Beach, southeast of Los Angeles. An approval would cap a 15-year permitting process to bring S…