San Benito County Water District San Benito County Water District

CONDITIONS EXPECTED FOR WATER YEAR 2009
Water supply for 2009 will depend on factors including rainfall, local surface water storage,
groundwater storage, and CVP operations and storage. Next year, water supply will continue to
be impacted by recent court decisions on the Delta smelt, Longfin smelt, and salmonoids.
In May 2007, the U.S. District Court in Fresno ruled that the existing 2005 biological opinion
for Delta smelt (issued by the U.S. Fish and Wildlife Service) was not in compliance with the
Endangered Species Act. The biological opinion guides pumping operations for the CVP (and
State Water Project) in the Delta with the intent of doing no harm to the endangered Delta
smelt. In August of 2007, the Court also ordered interim actions to protect the smelt. For 2008
allocations were 40 percent for agriculture and 75 percent of historical use based on the
Bureau’s M&I shortage policy.
While there is still considerable uncertainty about the percentage of allocation that is expected
to be delivered in 2009, some reduction from 2008 may be anticipated. The amount of Delta
pumping (and degree of water supply reductions) will depend not only on rainfall and storage
in CVP reservoirs, but also on the amount and direction of San Joaquin River flows in the Delta
and the abundance and distribution of Delta smelt as they occur next spring.
The San Luis & Delta Mendota Water Authority have already forecasted a low CVP allocation
based on relatively low storage in Northern California CVP reservoirs. As of November 6,
2008, storage in major Northern California CVP reservoirs (Trinity, Shasta, and Folsom) was
27 percent of capacity and 48 percent of the 15-year average. While long-range weather
forecasts are not particularly reliable, the climate predictions indicate a weak La Niña condition
in the Pacific Ocean, which is expected to continue into early 2009 (DWR 2009 California
Winter Outlook Workshop, November 21, 2008). In response, much of California is expected
to be drier than normal, although precipitation may be higher than normal in Northern
California, where key CVP reservoirs are located.
In 2008, the reduction in CVP imports did not result in an increase in groundwater pumping to
meet the total water demand as expected. Instead total water demand decreased by 25 percent.
The decrease could be attributed to several factors including the lack of groundwater
infrastructure to meet demand, changes in crops and agricultural water use, and the fallowing
of fields. These factors suggest that the decrease is short term and that groundwater pumping
will increase significantly in 2009 to compensate for the lack of CVP imports.
Total water demand in 2009 is expected to increase to the levels observed in 2007. Assuming
CVP import allocations are decreased to similar levels as water year 2008, groundwater
pumping in 2009 is expected to increase by about 8,300 af and 2,700 af for agricultural use and
M&I use respectively. The expected total groundwater pumping (33,800 af) is still significantly
lower than the historic high of 41,617 af (1991).
Annual Groundwater Report for Water Year 2008 December 2008
San Benito County Water District 44