Rethinking Water In The West

As I write this article at the beginning of the New Year, our first set of major storms has just arrived in California, bringing much-needed snow to the Sierra Mountains and rain throughout the state. Hopefully, the much-anticipated El Niño, which is the above-normal water temperatures in the eastern Pacific Ocean, is beginning to influence the weather in our region into a wetter pattern.

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In early January, reservoir levels on the Central Coast were still very low. Nacimiento and San Antonio reservoirs, which store water for the Salinas Valley, were only 17% and 3% full, respectively. The good news is that rainfall in the upper Salinas Valley has been closer to normal, but not so intense that it resulted in so much run-off to cause flooding. Perhaps these smaller but consistent rain events are recharging the Salinas Valley aquifer, which was at historically low levels in the fall.

El Niño Is No Drought Solution
While El Niño could significantly help with the drought in the West, when we look toward the future, we cannot rely on El Niño events to solve the water crisis in the West. First, large El Niño events are not very frequent. The last large El Niño that affected California was in 1998.

Secondly, strong El Niño conditions are not well correlated with increased rainfall. Compared to years with normal temperatures in the Eastern Pacific, the average increase in rainfall on the Central Coast during El Niño years has been 24% and only 14% for the San Joaquin Valley. Some El Niño years, such as in 1983 and 1998, have been associated with large increases in winter precipitation in California, but other strong El Niño years such as in 1992 and 1973 were associated with normal (1973) or below-normal precipitation (1992).

California has always had a limited and variable supply of water with periods of drought and periods of plentiful precipitation. The main differences today that affect the availability of water are that many more people live here than a generation ago, and irrigated land has steadily increased as the demand for fruits, nuts, and vegetables has grown.

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Additionally, concerns for the environment influence the amount of water available for farms and cities. Water is now needed to ensure that fish can migrate in rivers, to restore wetlands and coastal estuaries, and to provide habitat for wildlife.

Change In Water Policy
With these competing needs for water in the West, farmers are under tremendous pressure to do more with less water. The new Sustainable Groundwater Management Act (SGMA) is a major change in California water policy that likely will affect growers. During the current drought, many San Joaquin Valley growers were able to make up for their lack of surface water by pumping groundwater.

As a result of this shift from canals to wells, groundwater levels decreased substantially. Lower groundwater levels have caused land to subside and flows in rivers to decrease as more of the river water percolated back into the ground. SGMA mandates that a management agency is formed for each groundwater basin. The groundwater management agencies will have authority to determine how much water can be sustainably pumped from an aquifer.

The implications of this law are that limits will be set on how much water growers can pump from their wells. While this change in groundwater management will likely improve the sustainability of water supplies in California, it also will mean that water may become more limited for agricultural use.

In the early years of the state, water policy led to the construction of large infrastructure projects such as reservoirs, canals, and pumping stations that transport water to drier regions of the state and greatly benefited agriculture. Under SGMA, urban, agricultural, and environmental interests will all be considered in deciding future groundwater policy.

Weigh In On Groundwater Use
Those of us who work in agriculture need to be involved in helping formulate new policy on groundwater use. There are often misunderstandings about the water needs of crops and the effectiveness of water conservation implemented by growers. Additionally, agriculture needs to be part of the solution for using water more efficiently.

While much progress has been made in growing more with less water using innovations such as drip irrigation and higher yielding varieties, the agricultural community also can help with increasing water supplies. Water banking is an innovative idea that can help capture winter run-off by diverting excess river water into fallow fields or pastures to enhance groundwater recharge.

By adding strategic improvements on farms such as catchment basins, optimizing drainage ditches by widening them, and installing weirs and vegetation, a greater portion of rainfall can be infiltrated on site to recharge underlying aquifers. Farmers also can help conserve groundwater by irrigating with water recycled from urban areas instead of pumping from wells.

The current drought in the West will probably not be over in 2016, even if precipitation is above normal this winter. For many years, the water supply has been sufficient in Western states like California to support agriculture, but increases in demand for water will require continued effort to make the most out of every drop of water in both wet and dry years.

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