The Sacramento Valley spans 12 counties and includes a wide variety of terrain, ranging from the Sierra foothills and mountains in the north and east, to fertile farmland and delta in the south and west.
33 Nearly three million Californians live in the Sacramento Valley, powering a regional economy that generated $132 billion in 2012. The region includes large swaths of some of the state’s most critical watersheds, including the American and Sacramento Rivers and their tributaries. The Sacramento Valley is also home to the state’s largest dam, at Lake Oroville, and is a hub of the State Water Project, which supplies Central and Southern California.
In part due to its proximity to the Sacramento-San Joaquin Delta, the Sacramento Valley is a rich agricultural region, producing $3.7 billion worth of output annually, or close to 10% of the state’s agricultural total. The region’s primary agricultural products include walnuts, rice, almonds, wine grapes, and dairy.
34 Tourism is another notable industry in this region, which contains popular attractions such as Lake Tahoe. We discuss the potential economic impact of increasing temperatures and shifting precipitation trends on California’s winter recreation industry in greater depth in the sidebar here.
Residents of the Sacramento Valley, which includes the state’s capital city of Sacramento, are accustomed to warm summers. The region currently experiences about five weeks (38 days) per year with temperatures above 95°F, but the heat is likely to grow more intense and last much longer by the middle and latter parts of this century. The region will likely see 45 to 52 days (an additional one to two weeks) that are extremely hot each year in the next 25 years, and 54 to 72 such days—up to an additional full month and twice as many as the current average—each year by mid-century. By the end of this century, the region will likely experience 80 to 119 days, or as many as four full months, each year at temperatures above 95°F.
Increasing temperatures in the region also mean fewer cold days and nights, with potential consequences for a range of industries including agriculture and winter recreation. The number of freezing days across the region will likely decrease from a historical average of 12 days per year, down to three to nine days by mid-century, and just one to three days below freezing on average each year across the region by late century.
Other significant risks in the Sacramento Valley include:
- Rising energy costs: If we stay on our current emissions path, the Sacramento Valley is likely to see significant increases in electricity demand and energy costs. Demand will likely increase by 1% to 5% by mid-century and 5% to 15% by late century, likely raising energy costs by 1% to 9% by mid-century and as much as 10% to 31% by late century. There is a tail risk of more than a 37% increase in energy costs in the region by century’s end.
- Heat-related mortality: As temperatures increase across this region, so will the numbers of heat-related deaths. The likely range spans three to 26 additional deaths annually per 100,000 people (up to 750 additional deaths in total) by end of century, with a 1-in-20 chance of more than 43 additional deaths per 100,000 people, or 1,250 additional deaths per year.
- Declines in labor productivity: Increasing temperatures will also decrease the productivity of the nearly 20% of the Sacramento Valley region’s workers in high-risk industries, such as agriculture, construction, and manufacturing. The region will likely experience decreases in labor productivity for these industries of 1% to 2.2% by late century, with a 1-in-20 chance of a decrease of more than 2.9% over the same period.
SACRAMENTO-SAN JOAQUIN RIVER DELTA AND CLIMATE CHANGE
East of the San Francisco Bay and just south of California’s capitol city sits a hub of the state’s elaborate water system, the Sacramento–San Joaquin River Delta. This confluence of two of California’s largest rivers forms the West Coast’s largest estuary with hundreds of wildlife species. It is also a source of freshwater for more than 25 million Californians and millions of acres of farmland via the State Water Project and the Central Valley Project, which supply water for urban and agricultural uses to the Valley, Southern California, and the Bay Area & Central Coast regions. It’s already a challenge to meet the state’s numerous (and often competing) demands for freshwater while preserving the health of the Delta’s ecosystems and fisheries. Saltwater intrusion from the Pacific Ocean, which is likely to become more of an issue due to rising sea-levels, is another factor that can exacerbate these tensions.
Rising sea-levels—particularly when combined with storm events—are just one of several factors that could endanger the integrity of the Delta’s 1,100 miles of earthen levees, which protect the state’s water supply and the region’s agricultural, transportation, and energy systems from flooding and saltwater intrusion.
35 Earthquakes, land subsidence, and floods present serious threats to the aging levees as well. A levee failure could be costly, flooding valuable land that already sits below sea-level. For example, almost 12,000 acres of farmland flooded due to a breach in the Jones Tract levee in 2004,36 costing nearly $90 million to repair. Moreover, a levee failure could allow saltwater to mix with the Delta’s freshwater, increasing the salinity levels of water supplies and harming the local aquatic ecosystems. If the salinity levels become too high, the water export pumps in the Delta could be shut down.37 Even absent levee failures, saltwater will creep further inland from the San Francisco Bay into the Delta as sea-levels continue to rise. In response, water managers will need to release more freshwater into the Delta from upstream reservoirs in order to “push back” the salinity, especially during the warmer and drier months when freshwater withdrawals from the Delta tend to be higher. This will be further compounded by reductions in freshwater inflows from the Sacramento and San Joaquin Rivers during the spring, which will allow more time for saltwater intrusion. A recent study found that saltwater intrusion into the Delta could reduce the amount of freshwater for drinking and irrigation by up to one-quarter by the century’s end.38
FOOTNOTES
33 The Sacramento Valley region includes: Trinity, Shasta, Tehama, Glenn, Butte, Colusa, Sutter, Yuba, Yolo, Placer, El Dorado, Sacramento.El Dorado and Placer are large counties that encompass valley, foothill, and mountainous terrain, including Lake Tahoe and portions of the Sierra Nevada. For the sake of this analysis, we did not divide counties.
34 California Department of Food and Agriculture (CDFA), “California Agricultural Statistics Review 2013-2014,” (2014), available at http://www.cdfa.ca.gov/Statistics/.
35 J. Melillo et al, “Climate Change Impacts in the United States: The Third National Climate Assessment”; California Climate Change Center, “Economic Impacts of Delta Levy Failure due to Climate Change: A Scenario Analysis, “ (2006) CEC-500-2006-004-SD, available at: http://ccrm.berkeley.edu/pdfs_papers/delta_levee_failure.pdf.
36 Department of Water Resources, “Pumping Continues at Jones Tract” (2004), available at: http://www.water.ca.gov/news/newsreleases/2004/071604flood.pdf.
37 Bay Delta Conservation Plan, “Appendix 1A: Primer on the Delta and California Water Delivery Systems,” (November 2013), available at http://baydeltaconservationplan.com/Libraries/Dynamic_Document_Library/Public_Draft_BDCP_EIR-EIS_Appendix_1A_-_Primer_on_the_Delta_and_California_Water_Delivery_Systems.sflb.ashx.
38 National Research Council, “Sustainable Water and Environmental Management in the California Bay-Delta” (2012), available at http://dels.nas.edu/Report/Sustainable-Water-Environment/13394.
