The report’s findings were unequivocal: Given the current pace of water diversions, the San Francisco Bay and the Delta network of rivers and marshes are ecological goners, with many of its native fish species now experiencing a “sixth extinction,” environmental science’s most-dire definition of ecosystem collapse.Once a vast, soaked marsh and channel fed by the gushing San Joaquin and Sacramento rivers, the Delta has diminished dramatically over the previous century as those rivers and their mountain tributaries have been diverted to irrigate farms and Bay Area urbanity.