DWR Report Predicts Decrease in SWP Deliveries

The Department of Water Resources (DWR) released a draft report last week predicting decreases in State Water Project deliveries due to a variety of factors. The State Water Project Draft Delivery Reliability Report 2011 updates DWR’s assessment of its ability to maintain current (2011) and future (2031) State Water Project delivery reliability if no significant improvements are made to convey water through the Delta or to store more variable runoff expected with climate change.

The report finds that future SWP reliability will continue to be affected by two significant factors: operational restrictions on Delta pumping to protect species and climate change.

The report notes that under existing conditions, average annual Delta exports have decreased since 2005 from 2.9 million acre-feet (MAF) to per year to 2,607 MAF per year, a decrease of 351,000 acre-feet or 11.9%. Average annual Table A deliveries by the SWP have decreased since 2005 from 2.8 MAF per year to 2.5 MAF per year, a decrease of 294,000 acre-feet or 10.4%.

Information summarized in the report is aimed at helping local water officials update their water management plans and infrastructure development plans, DWR Director Mark Cowin says in a message at the beginning of the report.

“These results emphasize the need for local agencies to develop a resilient and robust water supply, and a distribution and management system to maximize the efficient use of our variable supply,” Cowin writes. “They also illustrate the urgent need to improve the method of conveying water past the Delta in a more sustainable manner that meets the dual goals of increasing water delivery reliability and improving conditions for endangered and threatened fish species.”

DWR is requesting comments on the draft report by March 12. The draft and related materials are available here.