Restrictions intended to protect native fish in the Delta, known as Reasonable and Prudent Alternatives (RPAs), have had significant effects on water exports over the past four years, under both wet and dry hydrological conditions.

This is the case despite the fact that a federal court has held the RPAs are unlawful. The charts below shows the water losses in the Delta and the allocations for the Central Valley Project south of the Delta (CVP) and State Water Project contractors (SWP).

Water loss due to BiOps
As the above chart shows, in recent years when water supplies were scarce, hundreds of thousands of acre-feet of water was required to be flushed out to the ocean while water contractors received only a fraction of their contracted amounts.


CVP allocations

During the following years legislation or regulatory action impacted water deliveries:

  • 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