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Episode released on December 12, 2024
Episode recorded on July 24, 2024
Newsha Ajami is the Chief Development Officer for Research in Earth and Environmental Services Area at Lawrence Berkeley National Lab in California. She is also the Mayoral appointee to the San Francisco Public Utilities Commission.
Highlights | Transcript
Per capita water use has been declining in urban areas in California: Los Angeles and San Francisco doubled their populations in last 40 years while water use remained stable, essentially halving per capita water use. California population doubled between 1967 and 2016 but water use only rose 13%: Cooley et al., 2022.
Consumption change detection applied to Costa Mesa in California: 2012 – 2016 drought, 75% of customers reduced water use, coinciding with state policies and media coverage (Bolorinos et al., WRR, 2020).
Decoupling population growth and water demand (Richter et al., 2020, Water).
Reductions in per capita water use linked to policy shifts in the energy sector focused on energy efficiency, with increasing efficiency in appliances (most high efficiency [HE] dishwashers, washing machines, showers, and low flush toilets).
Outdoor watering, irrigating gardens, serving no purpose, accounts for ~50% of residential water use in California. High irrigation water use linked to energy use because it is mostly treated water that is used for irrigation.
Public awareness during droughts, such as 2012 – 2016 drought in California, played a huge role in reducing water use, more than many drought policies (Quesnel and Ajami, 2017, Science Advances).
Public pressure and social norms played a big role in reducing water use during drought in California (Quesnel and Ajami, 2018, WRR).
Temporary versus permanent changes in water use during drought: Ajami found that ~ 30-40% of water use did not rebound in 8 years (Bolorinos et al., ERL, 2022).
Water utilities: provide high quality water out of the tap to 90% of US population. No real relationship between utilities and customers beyond receiving and paying bills (Ajami et al., 2014, The Brookings Institute).
Water charges reflect costs of services, not actual water costs.
Water utility costs: 60 – 80% fixed cost for operating and maintaining the system and 20 – 40% variable costs.
If conservation, efficiency programs, and decentralized reuse systems are not implemented in low-income housing, rental units and socially vulnerable communities, these groups may end up bearing a larger share of utilities' centralized costs in the future (Quesnel et al., 2020, ERL).
During droughts, people asked to conserve water, but water bills may increase because of the high fixed costs regardless of the water volume used.
Water utilities: Heavily depend on centralized and linear large infrastructure systems. Their business model reflects that reality (Ajami et al., 2014, The Brookings Institute).
Centralized wastewater recycling: high energy requirements to treat the water and move upstream for distribution, recycled water mostly used for flushing toilets and outdoor watering.
Digital era now: smart systems, can track water use (Daniel et al., 2023, npj Clean Water).
Decentralized recycling of water: showers and toilets each account for ~30% of total water use in homes. If shower water could be used for toilet flushing, this decentralized reuse would reduce water use by ~ 30%. Other opportunities also exist.
San Francisco, centralized recycling plant difficult to build because of lack of space. San Francisco put policy in place that commercial buildings ≥100,000 ft2 needs to recycle their wastewater onsite.
City of Austin: ordinance: developments ≥250,000 ft2 needs onsite water reuse system if not within 500 ft of centralized reclaimed water line.
Moving water from agriculture to urban areas: California, dry year contracts, land fallowed, water temporarily transferred to urban areas, like San Diego. Cannot permanently transfer water rights.
Colorado River Allocations, set in the 1920s according to the Law of the River, wet period, river overallocated. Ajami suggests water allocations proportional to water availability during dry and wet years.
Imperial Irrigation District in California, a small number of farmers, transferred 200,000 acre feet of water to San Diego County Water Authority under 2003 Quantification Settlement Agreement for up to 75 years.
Study in San Quintín, Baja, Mexico using desalinated water to grow berries for export to US. This industry developed because land and labor are cheap and energy is subsidized. However, desalinated water is only available for agrobusinesses and not for workforce. Development in these areas with policy vacuums can harm the environment and local communities and permanently alter a landscape, such as depleting groundwater and disposal practices for brine concentrate. (Smith et al., Env. Sci. & Policy, 2020).
Many of these issues need a systems perspective because we need to consider the interconnected implications for energy, food, water, and the ecosystem. If we develop solutions for water, we need to consider tradeoffs across systems.
There are a lot of parallels between water and energy, in terms of decentralization, prosumers (producer and consumer) of water and energy, and public awareness on where water comes from and goes to.
There are a lot of opportunities to adapt to climate extremes in the new digital age that will affect utilities and consumers in the future.
Adopted from Gonzales and Ajami, 2017, SCS and Gonzales and Ajami, 2015, HESS
Figure 2: Cluster water use and conservation. Cycle plot of average water use per cluster over the 10-year time period (Source: Quesnel et al, 2020, ERL)
