Off the Top of My Head by Russ Steele
It was a drought that is responsible for my interest in long term climate trends. In the 1970s my oldest daughter took an interest in the Anasazi cliff dwellings when we lived in Holbrook, Arizona for a year. The Strategic Air Command Radar Bomb Scoring Unit in Holbrook was my assignment upon my graduation from Air Command and Staff College in 1973. Not an auspicious assignment out of Command and Staff College, but I digress. Our year in Holbrook allowed us to take many family trips to the cliff dwellings scattered throughout Arizona and New Mexico, and eventually Colorado. But, Colorado is another story.
As we visited the cliff dwellings, one of the questions that kept coming up in our discussion was, why did this sophisticated community abandon their fields and dwellings and then vanish? The Internet was not yet a universal research tool, so we visited the local library and started researching possible causes: warfare, weather, famine, etc. We discovered there had been a long period of drought in the mid-11th and 12th centuries which may have contributed to the Anasazi cultural collapse.
Research by paleoclimatologists has confirmed that temperatures rose in the western U.S. from about A.D. 800-1300, known as the Medieval Warm Period, which translated into a series of droughts. The most devastating of these occurred in the mid-11th and 12th centuries, when dry conditions persisted for several decades. As I recall from our research, the longest we found was 27 years.
Paleoclimate data from tree rings and other sources also suggest that the mechanism driving drought during this Medieval Warm Period was eastern Pacific Ocean cooling. Much like a widespread extended La Niña event with cool sea surface temperatures strengthening a persistent moisture-blocking system of high-pressure off the West coast, nudging storm tracks north. This year the blocking is lower down the coast, creating droughts in New Mexico and Texas. We are fortunate that the La Niña this year resulted in a record-breaking snowfall. However, this has not always been the case.
During the Dalton Minimum there was a 13-year drought in coastal California according to Church Mission records. This was also a period when a deep La Niña weather pattern dominated the Pacific. The La Niña weather patterns have been associated with drought throughout climate history We are entering a period of low sun spot activity similar to the Dalton Minimum. The Pacific has entered a cool phase, which promotes more La Niña weather patterns. We could be on the cusp of some long-term periods of drought if history is an indicator.
How will we deal with these extended droughts? How do we store enough water for our needs? The environmentalists want to tear down existing dams and prevent the development of new dams to store the Sierra run-off, making it available for future use, especially during the drought periods yet to come. Droughts which will parch the fields in the Central Valley and shrivel costal and foothill vineyards, unless we store all the available run-off.
There are four dams to be decommissioned in 2020 on the Klamath River to increase the salmon run, without regard to the historical flows in the river under extended drought conditions. The Auburn Dam has been put on hold for an earth- quake scare, even thought the dam was redesigned to withstand any projected earthquakes.
A new "gravity style” dam was designed to replace the high thin arch dam originally proposed. The arch dam’s strength depended on anchoring itself into the walls of the canyon. This “gravity style” dam will be located at the same site, however, this new cement dam will be oriented straight across the canyon, and will depend on its inherent weight and strength for safety.
With respect to the fault that concerned everybody as a result of the quake at Oroville Dam in 1975, the Corps of Engineers reported: "the dam's present alignment is outside the trace of fault F-1 in the footprint of the original arch dam." Former Secretary of the Interior, Cecil Andrus, announced that: "a safe dam could be constructed on the North Fork of the American River."
Using the Auburn Dam for flood control would permit Folsom Lake to be used to store water, rather than flood control. The water volume in Folsom Reservoir could remain at 600,000 acre-feet during the winter, rather than being drawn down below 400,000 acre-feet, as is now done to help with spring flood control.
The difference in water levels would ensure availability of surplus surface water from Folsom during the winter to offset ground water pumping and provide more water for human consumption during extended droughts.
In addition to the Auburn Dam's capability to stabilize the Folsom Reservoir, water diversions from the Auburn Dam Reservoir could also be used to support the growing needs of Placer, El Dorado and San Joaquin Counties. Those opposed to the Auburn Dam claim there is plenty of water in the Sacramento region, no need to dam the American River. While that may be true now, it will not be true during a sustained drought. Basing long-term water needs on near-term history is an illusion.
According to the California Drought Contingency Plan, which worries a lot about global warming and does not address any long-term cold-driven droughts like those in the long-term climate history:
Droughts exceeding three years in California’s measured hydrologic record have been relatively rare in Northern California, which is where the majority source of the State’swater supply originates. Historical multi-year droughts include: 1912-13, 1918-20, 1923-24, 1929-34, 1947-50, 1959-61, 1976-77, 1987-92, and most recently the current drought which began in 2007. The 1929-34 Drought established the criteria commonly used in designing storage capacity and yield of large Northern California reservoirs.
The Drought Contingency Plan does not discuss building more dams, only the expansion of existing facilities, some off-river storages and better management of existing water resources. There are no action plans, only investigations. Those investigations are only based on solving the short-term droughts like those in 1929-34 and 1987-92, not the historical droughts in the paleoclimatology records. Short-term thinking avoids the need to build storage facilities like the Auburn Dam, which is not even mentioned in the Contingency Plan.
There are no new sources of water for the valley and foothills. The region will double in population between now and 2030. The needs of those millions of new people must be addressed in the future water resource planning. Unless we start now, there will not be enough water for those toilet flushers in the future, especially under long-term drought conditions.
It is time to start building more of those damn dams. The cold Pacific droughts are just around the corner, and it takes ten years to build a dam as large as the Auburn Dam. Waiting for the droughts to happen before taking action is not an option!
Russ Steele is freelance writer and blogs on issues at NC Media Watch.