“Everything depends on the manipulation of water – on capturing it behind dams, storing it, and rerouting it in concrete rivers over distances of hundreds of miles. Were it not for a century and a half of messianic effort toward that end, the West as we know it would not exist.”
In his book “Cadillac Desert,” Mark Reisner describes the unlikely rise of desert metropolises across the Western United States, often centering on the greater Los Angeles area, and details how their entire existence is predicated on the possibility of moving massive amounts of water from far away regions. This system of importing water over great distances has recently become increasingly susceptible to failure from climate change, drought, and earthquakes. These vulnerabilities for both Angelenos and the ecosystems from which the water is imported show that Los Angeles needs to establish a local water portfolio.
Currently, imported water consists of 63% of total usage in LA County, with the water coming from Owens Valley, Mono Lake, the Sacramento-San Joaquin Delta, and the Colorado River. The construction of the first Los Angeles aqueduct finished in 1913 under William Mulholland who used deceptive and nepotistic techniques to acquire the legal rights to the Owens Valley water. The original aqueduct erased a small but thriving community in the Owens Valley dependent on that water, and began the process of ecological failure. Subsequent extensions connected nearby Mono Lake to the exportation pipeline. Over the last century, spring and seeps have dried up, the lakes have experienced extreme salinization, groundwater-dependent vegetation have died, migrating bird populations have been eliminated, and dust storms have increased in both quantity and size. Exporting water from the Colorado River and the Sacramento-San Joaquin Delta has resulted in similar ecological damage, becoming especially dire in the Delta, where 2/3 of California’s water supply passes through.
Experts studying plate tectonic movements anticipate “the big one” along the San Andreas Fault in the next 100 years. A major earthquake could result in significant structural damage to water transportation devices, many of which are made of century-old concrete. A situation in which an earthquake damages any or all of the three major aqueducts transporting water to Los Angeles would quickly collapse into a humanitarian disaster dwarfing that of Hurricane Katrina.
It is evident that between the ecocide and danger of earthquake associated with water importation, a diverse and local water portfolio must be established by Los Angeles – and quickly. The question then becomes, how does Los Angeles transition from water-dependent to independent while population booms and climate change further exacerbates California’s aridity?
UCLA researchers working on the “Sustainable LA Grand Challenge” created a two-pronged approach to reaching zero imported water, tackling both the supply and demand sides of water. They took into account the expected 1.5 million population increase in Los Angeles county and two to three times as many heat waves, and created a plan to achieve 100% local water by 2050.
The first step to achieving a 100% local water portfolio is decreasing demand. Currently, Los Angeles has an average consumption rate of 98 gallons of water, per capita, per day. If consumption rates in residential spaces lowered about 25% to 75 gallons, which is a common rate in many cities across Western Europe, Southeast Asia, and Australia, the overall demand for water could decrease by 10%, ending the importation of 2 million acre-feet of water. Incentivizing the installation of water-efficient dish washers, washing machines, and smart trackers that track consumption in residential spaces, and mandating the installation of water-efficient cooling in commercial spaces could decrease consumption. Xeriscaping – or landscaping to minimize water usage – can be used to reduce single-family household water consumption, of which 54% goes to outdoor irrigation. Removing water-inefficient turf and replacing it with native, climate-appropriate plants, could be incentivized to achieve this goal as well.
Transitioning the city’s supply to completely local water is the main task at hand, and requires upgrading the city’s recycled water, storm water, and groundwater infrastructure.
Currently, recycled water fills only 1-2% of Los Angeles’s needs. Current studies estimate that number could eventually increase to 40%. To do this, the LA Department of Water and Power needs to upgrade three of its treatment plants (the Tillman, Glendale, and Hyperion plants), to recycle all of its water. Paired with the establishment of regulations for direct potable wastewater use, the highly treated wastewater could be pumped into LA’s basins and aquifers, then to one of the LADWP’s water filtration plants, and eventually to residents. As ambitious as this sounds, the similarly arid Israel currently recycles 85% of its water.
Implementing green stormwater infrastructure practices also would increase LA’s water supply of water, and could catch water that would otherwise runoff into the ocean or evaporate off of impermeable pavement. Installing roadside bioretention sties, stormwater cisterns, permeable pavements, and de-paving old/unnecessary roads and sidewalks would do a lot to provide new sources of water for the city as well as contribute to healthier groundwater systems. The “Grand Challenge” team estimates improving stormwater collection practices could supply an additional 10% of water needs for every inch of rainwater collected (LA has an average annual rainfall of 15 inches).
Improving the quality of local aquifers and groundwater basins is the final step in transitioning Los Angeles to a 100% local water supply by 2050. Los Angeles should build new groundwater filtration infrastructure including green streets made of semipermeable materials, biofilters, infiltration basins, and more to begin to replace local groundwater supplies that have been depleted. Remediation and restoration efforts are also required for previously-polluted groundwater sources, including LA’s primary local aquifer, the San Fernando Valley aquifer, which is currently being treated after contamination from industrial chemicals. The LADWP estimates that restored groundwater sources could supply 20% of the local water supply.
Mark Gold, Gavin Newsom’s Deputy Secretary for Oceans and Coastal Policy, in an op-ed for the LA Times states that going 100% local “won’t be easy and it won’t be cheap, but it can be done.” After all, the city that engineered their way out of a desert a century ago can certainly engineer their way into a greener world today.