Restrictions intended to protect native fish in the Delta, imposed under the Endangered Species Act, have had significant effects on water exports over the past decade, under both wet and dry hydrological conditions. Even after a historically wet winter in 2017, 2018 allocations were disappointingly low.

The charts below show the allocations for the Central Valley Project south of the Delta (CVP) and State Water Project contractors (SWP) and the water losses in the Delta over the past several years.

SWP allocationsCVP allocations


History of Water Supply Restrictions

  • 1991 – Endangered Species Act – Winter Run Salmon Temperature Control
  • 1992: Central Valley Improvement Act
  • 1994: Endangered Species Act – Delta Smelt Biological Opinion
  • 1995: Water Quality Control Plan/Clean Water Act
  • 1997: Anadromous Fish Restoration Program
  • 2000: Trinity Restoration Plan
  • 2008: Delta Smelt Biological Opinion
  • 2009: Salmon Biological Opinion