California’s Water Allocation Plan

On October 29th of 2008, the California Department of Water Resources (DWR)
announced that it would be allocating only 15% of the water requested by the
communities served by the State Water Project (SWP) in the State California;
this represents the second lowest allocation level in over 40 years. Several factors
have contributed to this conservative plan including a prolonged drought in the
region, lower than average snowfall, and a court decision to protect a small fish.
The California DWR is tasked with taking this all into account and managing the
State’s fresh water resources; a difficult task even in a wet year.

California, and indeed most of the southwest United States is in the midst of
a multi-year drought. Lower than expected rainfall has been recorded for the
past 2 years, and that trend is projected to continue in 2009. In fact the
pattern of repeated drought is well known to archeologists who study the
ancient cultures of the Southwest and to the Native Americans and settlers
who lived through such cycles. To overcome this hurdle, the State of California
began to build a system of canals, dams and reservoirs decades ago; this work
is ongoing and the DWR is currently the state agency tasked with the
maintenance, repair and construction of these facilities. These structures
have the effect of ‘leveling’ the wet and dry cycles, allowing the State to
collect and preserve a large percentage of the rainfall and snowmelt in the
wet years and then use that to sustain the State’s water demand during
the dry years.

Over the past two decades, California has seen two trends which both
contributed to the current low reservoir levels. The first is the increase in
population seen by California; over 15 million new citizens came to the state
in the past 30 years, almost doubling the population. This growing populace
obviously puts a greater demand on the state’s water supply, siphoning more
water from the reservoirs than planners 50 years ago expected. The second
factor may be more of a surprise; the past 30 years have been fairly wet years
and the State of California regularly had ‘surplus’ water. This bounty was one
of the main reasons that California’s Central Valley saw such agricultural
productivity during these years. Certainly there were dry periods, but on the
whole, the State experienced some of its wettest years in the 20th century from
1978 to 1998, the graph below from the University of California at San Diego
reinforces this point. The graph also gives some insight into the lag that
accompanies the rainfall cycle; for several years at the beginning of a ‘dry’
period, the groundwater supplies appear to be bountiful. This effect, however,
is only temporary and the abundant supply quickly disappears; California
appears to be entering this plunge to drought, currently.

Water Years

Figure 1 – The total annual rainfall (top) shows the wet and dry years;
the cumulative residual water (bottom) lags behind the rainfall trend by several

Another interesting factor in California’s water dilemma is, of all things, a fish.
In 2007, a Federal District Court judge protected the delta smelt, citing its
declining population and short lifespan as reasons for protection. The delta
smelt is a small, silver fish approximately 3-4 inches long; it lives in the San Joaquin-Sacramento River and has a one year lifespan. As a result of the short lifespan,
it is believed that the delta smelt is more prone to be affected by yearly variances
in water levels, as such; the judge limited the use of the Banks Pumping Plant
from December to June. As it happens, these pumps generate the water
pressures which allow the California and South Bay aqueducts to reach their
destinations. Because of this court ruling, the State of California lost the ability
to deliver approximately 625,000 acre-feet of water to central and southern California.

The State’s Governor, Arnold Schwarzenegger, has proposed building new dams
and channels to avoid the environmental issues associated with the delta smelt
and has been caucusing with other governors in the region to reach a common
understanding that may help to ease the situation. In the meantime local water
managers, faced with reservoirs that are less than half-full, are calling for
immediate reductions in use by farmers and households. If the State’s water
allocation plan holds at 15%, many fields will sit idle this summer. Of course,
a wetter winter or greater than expected snowfall would allow the DWR to
upwardly revise their allocation; this happened last year when the DWR initially
projected a 25% allocation and then later revised that to 35% after a wet winter.
But that isn’t a guarantee and the DWR’s conservative planning appears to be
warranted at this time. Looking forward, however, it appears that the State of
California needs a revision to its water plan, one that plans on much less water
availability for the next several years.