California’s Drought: Will a “Monster El Niño” Save Us?
Joseph Reichenberger, a professor of civil engineering in the Frank R. Seaver College of Science and Engineering, specializes in water quality management and wastewater treatment system design. He has worked and consulted extensively on local water issues and policy. Prior to joining the LMU faculty, he served as vice president and regional manager for Parsons Engineering Science, Inc. in Pasadena. Reichenberger also serves as a director of the San Gabriel Valley Municipal Water District and formerly was a commissioner on the San Gabriel Basin Water Quality Authority. Editor Joseph Wakelee-Lynch interviewed him in August 2015 about the possibility of California experiencing an El Niño year in 2015–16 and other matters related to the current drought in the state.
Predictions are lining up for a big El Niño year in the coming fall and winter. Let’s assume we get the same amount of rain as in the most recent El Nino year, 1997–98. Will that resolve the state’s crisis?
Unfortunately, the drought is a statewide issue and we in Southern California and Los Angeles depend heavily on imported water from Northern California. Certainly a “wet” south and a “dry” north or vice versa would be better than what we have now, but it would be good if El Niño also impacted Northern California and the Sierra Nevada Mountains and delivered a massive snowpack. There has been some discussion from the experts, and I’m certainly no climate expert, that the developing El Niño might not impact Northern California as much as Southern California. But let’s hope for the best.
By looking at rainfall records for Los Angeles, which should be representative of Southern California, one sees that from 2011 through June 30, 2015, (4 years), we received a total of 30.7 inches of rainfall. Considering our average is 14.8 inches per year, over the four-year period we should have received 59.2 inches, so we are “short” 28.5 inches.
In 1997–98, Los Angeles received 31.0 inches of rainfall, 16.2 inches above normal. But even with that, we would still be 12.3 inches “short.” In order to get back on the “plus” side, we would need 43.3 inches of rainfall. Well, it’s possible! But not likely. The maximum amount Los Angeles received in any one year, over the last 138 years, was 38.2 inches. So maybe we can hope for a two-year period, maybe an extended El Niño.
To get back to even, we need to have 58.1 inches over a two-year period. Well, that has not happened either. The most we received over a two-year period was 54.1 inches (1888–90). For the period 1996–98, we received 43.4 inches over the two-year period. There have been several periods with more than 50 inches. So it is possible we will be “close” and with a good wet winter this year and next we should be close to getting back to normal — but not quite.
I am more concerned about Northern California, however. The National Weather Service indicates the Sierra Nevada Mountains have a one- to two-year precipitation deficit — not unlike Los Angeles. So it will take more than a single wet year to catch up. We’ll need two good years.
In summary, while El Niño may be coming, we still have a long way to go, and we need to be mindful of our water use and use it wisely and efficiently.
When a heavy rainy season follows several years of severe drought, is it difficult to capture and make use of a sudden abundance of precipitation?
Several “things” are at work here. First, the soil mantle is dried out to substantial depth due to the extended dry periods. Before we get significant runoff volumes, the ground will have be saturated; so some of the initial rainfall will go to making up for the soil moisture “deficit.” But the extent to which this occurs depends on how intense the rainfall is. Intense storms will cause a lot of runoff since there is not enough time for the soil to take up the moisture.
These first storms will also bring substantial erosion. After years of drought, the plants and their root systems are almost non-existent on the hillsides, and the rainfall, instead of hitting a good stand of plants and trees, will directly impact the soil and create substantial erosion from the impact which will fill up our reservoirs with debris.
Also, years of dry weather makes some soils less able to take on water. I’m sure you’ve had some potted plants that had the soil dried out and you put water on the soil only to find that it formed “water globs” on the surface and did not penetrate. This phenomenon also occurs in some soils in the mountains and the first rain can result in large amounts of runoff because the water will not penetrate the soil.
Intense storms with large amounts of runoff bring huge sediment loads. In Southern California, we have a number of flood control and water conservation reservoirs in the mountains designed to capture this runoff and hold it till summer when we can release it to percolation basins and recharge the groundwater. Unfortunately, many dams and reservoirs are heavily silted up and have lost substantial capacity to store water. So when these reservoirs fill up from heavy rains, the water will “spill” over the dams and discharge to the storm channels. Much of this water will be lost to the ocean. It would be nice to clean out the debris and sediment to make room for water, but it is not easy to do so. Desilting reservoirs is a very expensive and complex process.
Ideally, we would like to get the precipitation in the form of frequent gentle storms. That would result in the greatest opportunity for rainfall infiltration into the soil and groundwater recharge and reduce the volume of runoff so that we can accommodate it in our reservoirs. But even so, we may not have enough capacity because of the siltation.
Los Angeles has responded well to calls for water conservation during the past year, but can the county reduce consumption by the same amount in the coming year? Does agriculture account for a significant amount of water consumption within L.A. County?
Right now most, if not all, of the people in Los Angeles are mindful of the drought and are trying to do their best to use water wisely and efficiently. Conservation is certainly in our mindset. After a drought ends, there has always been a lingering drought effect, at least for a few years. But I think this drought has affected us more than previous droughts. People are aware this might be the new “normal.” People have spent money replacing lawns, transforming gardens, improving irrigation systems, installing low water-using appliances, etc. This will have a long-lasting impact. The state has come out with a new model water efficient landscape ordinance, which replaced the one issued in 2009, that is said to reduce landscape water use by another 20 percent. The state is requiring all municipalities to adopt it or a similar ordinance. This will impact all landscaping projects of 500 square feet or larger. So this will have a long-term impact. In my opinion, the water conservation and water efficiency mindset will continue on — maybe not to the “brown lawn” degree, but certainly water use will continue to be reduced on an individual basis. But overall water use will increase due to growth in population.
Decades ago, agriculture was a major industry in Los Angeles, and it still is to some degree. We don’t think of Los Angeles with fields of corn and wheat, or maybe even rows and rows of carrots and tomatoes. But there is a huge nursery and plant and tree industry in Los Angeles with over $100 million in annual value. Just look under any of the electrical tower rights-of-way. But they are able to pay the cost for water.
According to the Metropolitan Water District of Southern California’s 2013 Annual Report (the latest one published), agricultural water deliveries to all of its member agencies was 23,300 acre feet in 2013. Their total delivery of water was almost 1.7 million acre feet. So agricultural deliveries were only about 1.3 percent or so of the total. This is for all of their service area, which includes significant agricultural areas in the Inland Empire, Ventura County and San Diego County. So, from a practical standpoint, agricultural water use in Southern California, and Los Angeles in particular, is not significant.
California’s drought problem seems to be turning into a western U.S. problem. Are some states in worse shape than California, or better shape?
According to the latest data from the National Drought Mitigation Center in Lincoln, Nebraska, more than 58 million people are affected by the drought in the western U.S. Exceptional and extreme drought conditions exist for California, Nevada, Oregon, Idaho, western Montana and Washington. California is probably in the worst shape. But western Oregon and Washington, where there are significant fires going on, are also impacted. It is interesting that the Colorado River Watershed states of Colorado and Wyoming are not substantially impacted, so it is possible that we, in Southern California, may get some relief in terms of water supply.
In the Seattle area, the drought is extreme. This should be a concern for the residents there who rely heavily on surface water supplies. In the Los Angeles area, we are fortunate because we have groundwater reservoirs we can draw on during extended droughts.
Go to LMU Magazine to read previous interviews with Joseph Reichenberger about California’s water crisis.