A prominent Sacramento-area economist says Gov. Jerry Brown’s $15.5 billion plan to overhaul the troubled Sacramento-San Joaquin Delta doesn’t make financial sense, with costs far outweighing the benefits. Jeff Michael of the University of the Pacific, who has been a persistent critic of Brown’s plan to build a pair of massive tunnels beneath the Delta, said the project would likely deliver just 23 cents worth of economic benefit for every $1 spent.