Climate change will impact California’s water supply. The California Department of Water Resources (DWR) released a whitepaper in 2008 which listed the impacts the state’s water supply will face. The impacts included: reduced snowpack, drought, floods, water quality, sea level rise, and hydroelectric generation.
Reduced snowpack. Experts project there will be a reduction in the Sierra Nevada snowpack. The DWR whitepaper calls it “California’s largest surface reservoir.” Currently, snowmelt provides an annual average of 15 million acre feet of water which is released between April and July every year. The whitepaper states that “much of the state’s water infrastructure was designed to capture the slow spring runoff and deliver it during the drier summer and fall months.” The DWR projects that the snowpack will experience a 25 to 40 percent reduction from the historic average by 2050.
Drought. A rise in temperatures coupled with rainfall and runoff patterns changes “will exacerbate the frequency and intensity of droughts.” Regions relying on surface water (streams, rivers, and lakes) “could be particularly affected” which would increase the demand on groundwater. Drier soils and more forest fires result from drought. In addition, warmer temperatures are likely to increase evapotranspiration rates which would extend growing seasons and increase the amount of irrigation needed for many crops, urban landscaping and environmental water needs.
Floods. There is a potential for more floods for two reasons: 1. Greater storm intensity is projected by scientists, 2. Watershed vegetation and soil moisture conditions changes are likely to change runoff and recharge patterns.
Water quality affected. Water quality may be affected by changes in the timing of river flows and warming atmospheric temperatures. Flood peaks may cause increased erosion which would result in “turbidity and concentrated pulses of pollutants.” The integrity of water works infrastructure may be threatened by flooding.
Sea level rise. Sea levels are rising and are expected to continue to do so. Peer-reviewed studies estimated sea level to rise between seven to 55 inches by 2100 along the California coast. A seven-inch rise would increase flooding along the California coast, and could also cause “catastrophic levee failures in the Delta.” An increase in seawater penetration in the Delta would degrade drinking and agricultural water quality.
Reduced reliability of hydroelectricity operations. The reliability of the state’s hydroelectricity operations will be reduced by climate change. The largest source of clean energy in California is hydroelectricity. Changes in the timing of inflows to reservoirs may be greater than generation capacity which would force water releases over spillways and “result in lost opportunities to generate horsepower.” During summer months, decreased snowpack, earlier melting and higher snow elevations may result in less water available for generation.
Water conservation and efficiency is needed
The Pacific Institute issued reports on urban and agricultural water efficiency, and the findings of the reports have been adopted by the DWR in the California Water Plan. One of the findings is that conservation and efficiency can save one million acre feet of water quickly, and six to eight million acre feet by 2020.
“Improving the efficiency of our water use is the cheapest, easiest, fastest, and least destructive way to meet California’s current and future water supply needs,” said Dr. Peter Gleick, president of the Pacific Institute and one of the world’s leading authorities on water.
“There is no ‘silver bullet’ solution to California’s water problems,” said Gleick. “Everyone involved in state water debates will acknowledge the need for diverse answers or a ‘portfolio’ of solutions – but current proposals for meeting water challenges are inadequate and largely misdirected.”
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