CSPA has released a report detailing the impacts to delta smelt and salmon from the demise of the mid-April – mid-May limits on Delta exports. The export restrictions were part of the Vernalis Adaptive Management Program (VAMP) and served to help protect out-migrating San Joaquin River salmon from being drawn to the export facilities during the San Joaquin River Spring pulse flow. They also provided critical protection to delta smelt, especially during drier years.
The export limitations, which were designed to reduce export pumping to about 1,500 cubic feet per second (cfs), ended as the ten-year VAMP experiment expired in late 2010. The San Joaquin River pulse flow continues as a requirement of the State Water Board’s water quality standards adopted in 2000. In 2013, the pulse flow was exported and became a defacto water transfer. The Department of Fish and Wildlife’s Summer Townet Survey delta smelt abundance index dropped to 0.7 in 2013 and is similar to the extremely low indices between 2005-2010. The index averaged 21.2 between 1959 and 1978.
This year has been a really, really bad year for delta smelt, which were brutally hammered in July by operations of the state and federal export projects. Earlier this month, CSPA released a report detailing how the state and federal water projects increased exports from 2,000 to 10,000 cfs at the end of June and dramatically reduced Delta outflow to 5,000 cfs in early July. This caused the low salinity zone and delta smelt to be drawn into the western Delta where they encountered lethal temperatures. DFW’s Fall Mid Water Trawl will reveal the full extent of this year’s disaster.