Variable Delta Workshop

One of the goals of the CALFED Science Program is to provide authoritative and unbiased descriptions of scientific knowledge. To fulfill this goal, the Science Program holds workshops designed to provide a forum for discussions and the exchange of information among Scientists, Stakeholders, Agency Staff, and the public about topics important to the region. These workshops synthesize the science related to complex problems and provide advice for undertaking specific complex tasks in support of Delta planning and decision-making.

The "Variable Delta Hypothesis," which was originally outlined in the Public Policy Institute of California (PPIC) report "Envisioning Futures for the Sacramento-San Joaquin Delta," suggests that increasing the variability of estuarine habitat attributes, like salinity and residence time in the Delta, will improve habitat conditions for native estuarine fishes (and the introduced sport fish striped bass), and decrease habitat suitability for undesirable invasive species like Corbula amurensis and Egeria densa.

As part of its ongoing process to clarify the implications of a variable Delta, the CALFED Science Program sponsored a one-day technical workshop to discuss key aspects of the "Variable Delta Hypothesis" and to explore and clarify the state of science on which it is based in support of the Delta Vision, Bay-Delta Conservation Planning, and Delta Risk Management Strategy efforts.

Update: The Variable Delta Workshop Final Report is now available.

Variable Delta Archived Webcast

Workshop Product

The Science Program produced a written report from the workshop. This report included:

  • the major points made by each presenter,
  • an overview of key scientific agreements and uncertainties highlighted during the workshop, and
  • a summary of the facilitated discussion that follows the speakers' presentations.

Further, the report and the speakers' presentations are posted on the CALFED Science Program website (


    8:00 a.m.
  1. Introduction to the Workshop - Dr. Ron Ott, CALFED Science Program
  2. Animation of Salinity in the Estuary at the Current Level of Development - Tara Smith, California Department of Water Resources
  3. Trends in Hydrology and Salinity in the Suisun Bay and Delta - Dr. Greg Gartrell, Contra Costa Water District
  4. Good Fish, Bad Fish: Responses to Increased Environmental Variability in the Delta and Suisun Marsh - Dr. Peter Moyle, University of California Davis
  5. Habitat Requirements, Life Cycles, and Population dynamics of Corbula amurensis and Corbicula fluminea - Dr. Jan Thompson, U. S. Geological Survey
  6. Reconciling Water Project Operations and Ecosystem Function: a Hydrodynamic Perspective - Dr. Jon Burau, U. S. Geological Survey
  7. What Are the Big Knowns and Unknowns Regarding a Variable Delta? - Dr. Wim Kimmerer, San Francisco State University
  8. Panel Discussion (including Public Comment) facilitated by Dr. Ron Ott
  9. 5:00 p.m.    Adjourn