The California Delta


More than half of all Californians rely on a single source for fresh water: the California Delta watershed.

Once an inland sea, the 1,100-square mile California Delta watershed provides an estimated 7 million acre feet of water per year.

  • California's largest single source of fresh water.
  • The largest estuary on the west coast of the Americas.
  • Nearly half the total river flow in the entire state.
  • Feeds the largest water delivery systems on earth.
  • Home to 750 distinct species of plants and animals.

This map from 1873 shows the California Delta in gray east of San Francisco Bay.