After four months of comment representing thousands of hours of labor from advocates for the embattled estuary known as the California Delta, the Delta Stewardship Council voted 5-1 last week in favor of an amendment that endorses “dual conveyance” — the latest euphemism for a project to dig two of the largest water tunnels the world has ever seen. Touted by Gov. Edmund Brown Jr. as one of his legacy projects he hopes to leave to Californians, the tunnels would be an underground version of his voter-rejected Peripheral Canal of the 1980s.