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Blog of the California Institute for Water Resources | Univ of California | Ag & Natural Resources
by Vincent F. Lazaneo
on October 26, 2015 at 11:55 AM
109%: Another Perspective on the California Drought and Landscape Water Use  
By Vincent Lazaneo, Urban Horticulture Advisor Emeritus  
I understand the desire to defend urban landscapes and justify the amount of water we use to maintain them. But I think the focus of the article 9%: Perspective on the California drought and landscape water use by Dennis Pittinger and Don Hodel is short-sighted. The discussion of issues raised in the article would, I believe, benefit from a broader perspective. It should take into account both the historic record of drought in the region and the profound changes caused by global warming that have begun and are predicted to accelerate as the century progresses.  
The historic record of our region’s climate over the past 2,000 years has been scientifically reconstructed using proxy data. Researchers have studied the growth rings of long-lived trees and ancient stumps at the bottom of Mono Lake, geological records that reveal the previous levels of Mono Lake and analysis of deposits deep under San Francisco Bay which collects sediment from a large water shed. The research and its implications are presented in a 20-minute long PowerPoint talk “Climate Change and Paleoclimatology: 2013/2014 in Perspective” by Lynn Ingram, professor of Earth and Planetary Sciences at UC Berkeley. It is available on-line at: I recommend viewing this presentation.  
We have experienced some of the warmest years on record since the turn of the century. According to Ingram, the paleoclimate record shows that past periods of warming were associated with drier conditions in California. We have difficulty coping with recent droughts that last less than a decade but during the medieval warm period there were two dry periods with century-long droughts that had 60-70% of average precipitation. The proxy data shows that our climate is influenced by cyclical patterns and Ingram states that “we see wet/dry cycles over the past 2,000 years with periods of 30, 65, 90 and 200 years”. She also states that “the past 150 years have been unusually wet when viewed over the past 2,000 year period. The 20th century was a wetter century and this is when all our water development population growth and agricultural industry were established.”  
Ingram concludes “it’s possible the climate may now be shifting to a drier regime. We have already seen the impact of warming that’s been occurring since 1960. We are seeing a reduced snowpack that will continue into the future, and a drier climate with increased evaporation rates, so we’ll have drier soils, more frequent wild fires and increased dust levels.” It is also predicted that we will have a more extreme climate…that will produce larger floods and deeper droughts in the future.  
Considering the data and its implications, it’s difficult to justify maintaining the status quo with respect to the use of water for landscape irrigation. Our water pie is not as large as we thought it was and it will need to serve more people in the future as our population continues to increase. We will pay more for water and have less to use although this may be alleviated somewhat by desalinization and reclaiming water from the waste stream. (The city of San Diego plans to raise water rates by 41% over the next five years. It also has a large desalinization plant under construction and is considering claiming potable water from sewage water. The latter is already being done in Orange County.)  
The amount of water we can obtain from precipitation is limited and the use of water for any purpose reduces the amount available for other purposes. A large amount of the water from precipitation (about 50% I have heard) is devoted to environmental purposes such as maintaining lake levels, river flows, wetlands, etc. The percentage of total water used for this purpose could increase during a drought since there’s a minimum threshold for the amount of water needed. Providing enough water for environmental needs would leave less water for other sectors including agriculture, industry and urban.  
Potable water has been plentiful and cheap for several decades and we don’t consider it a valuable resource. This attitude has begun to change during the drought. This is good because future conditions will require us to use water more efficiently and curtail wasteful practices. I believe it would be beneficial for the urban landscape sector to be proactive in this effort. We should lead by example and do what is needed to create sustainable water-wise landscapes that are less dependent on supplemental irrigation with potable water.  
Using as much water as you desire and can afford and applying more potable water on a landscape than a sight normally would receive from annual precipitation is not a sustainable practice. Realistic limits should be set on the amount of potable water used for landscape irrigation. We should encourage the creation of landscapes that require little or no supplemental irrigation. The current drought has provided an opportunity to reevaluate our landscapes and the lessons we are learning on how to have functional landscapes with less water should not be forgotten if an El Nino temporarily refills reservoirs. About 19% of the state’s total energy is currently used to transport and process water. Reducing the amount of water used on landscapes would reduce the need to generate electricity from fossil fuels and help decrease carbon emissions into the atmosphere.
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