The $11 billion first leg of California’s plan to divert water from its largest delta will pay dividends for cities and farmers and improve water quality, according to a state-sponsored study released Tuesday. The long-awaited cost-benefit analysis, conducted by a University of California, Berkeley professor, concludes that it’s worth it for water suppliers to foot the bill for the ambitious public works project touted by Gov. Jerry Brown. It finds “under all scenarios analyzed” that the California WaterFix or “delta tunnels” would benefit stakeholders and provide billions in net benefits.