The largest estuary on the West Coast of the Americas lies at California’s heart. It’s a place of constant change, affected by daily tides, sea-level rise, water diversions that serve 25 million residents and a growing population closing in around it. Yet most of those people have no idea the Delta is the subject of one of the largest habitat restoration projects ever proposed in the U.S. Known as Eco Restore, it is a companion to another proposal called California WaterFix, which calls for reforming water diversions by building two giant tunnels.