Droughts in California

There have been several severe droughts in California history. As the most populous state in the U.S. and a major agricultural producer, drought in California can have a severe economic as well as environmental impact. Drought may be due solely or in combination to weather conditions; economic or political actions; or population and farming.

A dry riverbed in California, 2009

Causes

Water in California is very closely managed, with an extensive pipeline network to serve the most populated and dry areas of the state. Precipitation is limited, with the vast majority of rain and snowfall occurring in the winter months, in the northern part of the state. This delicate balance means that a dry rainy season can have lasting consequences.

Lack of new infrastructure

Not much water infrastructure has been built since 1979, despite a doubling of the population since that year. ^{[1] [2]}

Leaky distribution systems

In Water Year 2015 (October 2014-September 2015) 9.4 Million acre-feet was dumped into the San Joaquin Delta, but only 1.9 Million of these acre-feet were recovered into water distribution systems.^[3]

Reservoir capacity reserved for flood control

Due to limited spillway flow design, reservoirs cannot be quickly drained in anticipation of major storms. This limits how much of a reservoir's capacity can be used for long-term storage.^[4]

Shasta Lake limited to 87 percent capacity

On March 18, 2016, during a period of increased rainfall due to El Nino weather conditions,^[5] the discharge rate at Shasta Lake (California's largest reservoir) was increased to 17,515 CFS, ^[6] or more than 3 times normal summer usage. This rate of discharge has not been seen since June 7, 2011. ^[7] This water is being dumped into the Pacific Ocean for flood control reasons (more rain predicted for the week of March 21, 2016) and the rate of release will increase to 20,000 CFS.^[8]

Lake Oroville limited to 85 percent capacity

On March 27, 2016, during a period of increased rainfall due to El Nino weather conditions,^[5] the rate of releases from Lake Oroville (California's second largest reservoir) were tripled to 7,000 CFS.^[9] Even though the water level was 46 feet from the top, this was enough to hit the flood control limit ^[10][11][12] and has led operators to open the spillway for the first time in 5 years.^[13]

Folsom Lake limited to 60 percent capacity

A flood risk exists when Folsom Lake is above 60 percent.^[14] On March 7, 2016, Folsom Lake was at 68% capacity.^[9] The excess 8% of capacity is not allowed to be used ^[15] and had to be released to avoid potential property damage.^[16]

A spillway improvement is scheduled to be completed in 2017. This will allow short-term weather forecasts to be taken into consideration rather than using the crude 60% rule. This is possible because the river below the dam is wide enough to handle large releases on short notice. ^[17]

The spillway improvement at Folsom lake is still under construction.^[18] Because the improvement is still under construction, 8000 acre-feet had to be released from Folsom Lake on March 7, 2016 to meet the US Army Corp of Engineers rule mandating a maximum 60 percent capacity during the winter.^[19]

On Tuesday, March 8, 2016, releases were scheduled to double from 8,000 CFS to 15,000 CFS.^[20] This resulted in 29,000 acre-feet in being released.

From March 7 to March 19, a cumulative 280,000 acre-feet of water was released into the Pacific Ocean via the Folsom Dam spillway.^[21]

Missing precipitation

According to the NOAA, a rainy year does not end the drought.^[22] Academic articles tend to define drought as missing precipitation (or dry years), while news and politics tends to focus on water shortage.

Weather cycles

The 2012–15 North American Drought was caused by conditions of the Arctic oscillation and North Atlantic oscillation which removed winter storms from the U.S. the winter of 2011–2012.

Climate change

Climate change causes more dry years.

Water rights complexity

Without changes in water use, it would take about 6 dry years to deplete the state's reservoirs. ^[23]

Large water consumers

Approximately 2.7 trillion gallons are effectively exported from California every year in cattle feed. ^[24] This is more than California's annual urban water consumption, which is only 2.3 trillion gallons. ^[25] California's annual cattle feed production is worth only $1.3 billion. ^[26]

Also, from 2008–2015, 1.4 trillion gallons were dumped into the ocean to save 36 Delta smelt. ^[27] An alternative, salinity barriers, is being installed.^[28]

Supply and Demand

Water is not a free good. ^[29] In fact, it's expensive. ^[30] These conditions lead to awareness of water management challenges. ^[31]

Effects

Irrigation restrictions in cities

Rules are imposed on local water agencies.^[32]

In response to the severe California drought, in April 2015, Governor Jerry Brown issued an executive order mandating statewide reductions in water use. The mandate aimed to reduce the amount of water consumed statewide in urban areas by 25% from 2013 levels. The State Water Resources Control Board (SWRCB) proposed regulatory instructions that grouped urban water utilities into nine tiers, with conservation standards ranging from 8% to 36%.^[33]

Increased water prices for farmers

Water costs have soared from $140 per acre-foot in 2013 to $1,100 per acre-foot in 2014. ^[34] This has a crippling effect on the industry. For example, dairy farmers are going out of business. ^[35]

Historic droughts

Since 1900, the following dry years have had significantly below-average precipitation.

• 1917–21
• 1922–26
• 1928–37
• 1943–51
• 1959–62
• 1976–77
• 1987–92
• 2007–09
• 2012–15

^[36][37]

Mono Lake in 2006 (left), and Mono Lake in August 2014

1929–1934

The Central Valley Project was started in the 1930s in response to drought.^[38]

1950s

The 1950s drought contributed to the creation of the State Water Project.^[38]

1976–77

1977 had been the driest year in state history to date.^[39] According to the LA Times, "Drought in the 1970s spurred efforts at urban conservation and the state's Drought Emergency Water Bank came out of drought in the 1980s."^[38]

1986–1992

California endured one of its longest droughts ever observed from late 1986 through early 1992. Drought worsened in 1988 as much of the United States also suffered from severe drought. In California, the six-year drought ended in late 1992 as a significant El Niño event in the Pacific Ocean (and the eruption of Mount Pinatubo in June 1991) most likely caused unusual persistent heavy rains.^[40]

2007–2009

2007–2009 saw three years of drought conditions, the 12th worst drought period in the state's history, and the first drought for which a statewide proclamation of emergency was issued. The drought of 2007–2009 also saw greatly reduced water diversions from the state water project. The summer of 2007 saw some of the worst wildfires in Southern California history.^[41]

2011–2016

Progression of the drought from December 2013 to July 2014

The period between late 2011 and 2014 has been the driest in California history since record-keeping began.^[42] In May 2015, one state resident poll conducted by Field Poll found that two out of three respondents agreed that it should be mandated for water agencies to reduce water consumption by 25%.^[43]

The 2015 prediction of El Niño to bring rains to California raised hopes of ending the drought. In the spring of 2015, the National Oceanic and Atmospheric Administration named the probability of the presence of El Niño conditions until the end of 2015 at 80%. Historically, sixteen winters between 1951 and 2015 have created El Niño. Six of those have had below-average rainfall, five had average rainfall, and five had above-average rainfall. However, as of May 2015, drought conditions have worsened and above average ocean temperatures have not created large storms.^[44]

The drought led to Governor Jerry Brown's instituting mandatory 25 percent water restrictions in June 2015.^[45]

Many millions of California trees have died from the drought -- approximately 12 million in Southern California by one June 2015 estimate.^[46] That estimate increased to 102 million according to a November 2016 U.S. Forest Service announcement based on aerial surveys, including 62 million in 2016 alone.^[47]

Mitigation

Plastic balls floated on reservoirs prevent evaporative losses.^[48]

Long-Term Mitigation

Voters' approval of the Proposition 1 water bond in 2014 has been interpreted as an eagerness to add flexibility to California's water system.^[49]

In early 2016, Los Angeles County began a proactive cloud-seeding program.^[50]

See also

• Land surface effects on climate
• California drought manipulation conspiracy theory

References

External links

• State of California: drought
• United States drought monitor for California
• USGS: California Water Science Center, Drought
• Department of Water Resources: California Data Exchange Center, and CDEC daily drought summary
• historical Palmer Drought Index maps