CALFED and the Delta Today
At this point in CALFED’s history, the future of the Delta is more important than ever. It is, in fact, one of the leading issues facing California. Water has always been one of the state’s most pressing and complex issues, and because of problems facing the Delta today, the concern over the Delta has heightened. These concerns are focused in the following areas:
Pelagic Organism Decline
Pelagic or open water fish have suffered major declines in their populations over a decade or more and some have suffered abrupt declines in recent years. These species of concern – and in some cases threatened – include the delta smelt, threadfin shad, longfin smelt and striped bass. The reasons behind their decline have been the focus of CALFED scientists for years.
The Delta is home to more than 750 species of flora and fauna. If every microscopic organism was catalogued, the number of species would reach into the thousands. However, the Delta is also home to more than 250 non-native invasive species, some of whom are a threat to its ecosystem. Man has introduced invasive species into the Delta by something as simple as emptying an aquarium or launching a boat.
Levee Fragility – Earthquake Vulnerability
For the most part, the Delta’s 1,100 miles of levees are unengineered dirt structures that have weathered erosion from water and intrusion from vegetation for 150 years. Many of the Delta’s levees have been repaired and restored by state and federal agencies. However, issues with their stability continue to plague the Delta. Two recent studies indicate that a moderately strong earthquake centered on faults east of the Delta could cause catastrophic failure.
Global Warming – Sea Level Rise – Land Subsidence
Global warming and the accompanying decrease of the world’s snowpack will mean that sea level rise will lead to permanent and far-reaching issues in the Delta. Scientists who are studying these effects predict up to 5.8°C temperature increase by 2100, a loss of one-third of the world’s snowpack by 2050 and up to 3 feet rise in sea level by 2100. These are serious issues for the Delta, most of which has subsided to -5 to -25 feet below sea level.
Flooding from heavy winter rains and spring run-off has always plagued the Delta and most winter flood
seasons include some degree of levee impacts. Flooding accelerates levee erosion and levee over-topping,
burrowing and piping lead to instability, seepage and levee breaks. The worst recent winter flooding was
in 1986, when levee breaks inundated four Delta islands and flooded one community.