NIMBY dogma claims that California shouldn't allow any growth due to a water shortage. The Bay Area is currently in an extreme/exceptional drought. Under these conditions, it's not unreasonable to ask if California has enough water to keep growing.
The short answer is yes, but only if we grow correctly.
How is water used in California?
Before we can answer if California can grow, we must first understand how we currently use our water.
According to the Public Policy Institute of California, "statewide, average water use is roughly 50% environmental, 40% agricultural, and 10% urban." Environmental water use "refers to water in rivers to protect “Wild and Scenic”, instream flows to maintain habitat, water to manage wetlands, and water to maintain urban and agricultural water quality."1
For the purposes of governmental policy influencing growth, we can more-or-less consider environmental uses untouchable. The usage varies by year, fluctuating with rainfall, and that water goes largely unconsumed by any human activity (with the exception of some water that seeps into aquifers or flows to streams used for irrigation). The state has pretty good reasons for ensuring this water remains untouched -- it's vital to many habitats and the continued health of our wildlife. That leaves us with 80% of water used by humans sent to agriculture, and 20% sent to cities and towns.
So this kind of gives away the game immediately: humans are only using 50% of all easily available water, and most of it goes to growing water-intensive crops in an arid valley. That's silly, but government policy up until the 1980s encouraged situating farms in the central valley due to underpriced water. Starting in the early 1980s, California grew a robust water market where the price of water could actually respond to supply and demand. The market has been a remarkable success, and despite growing population and higher intensity farming, total water usage by the agricultural sector actually declined by 0.33% between 2000 and 2015 [1]. This reduction in usage was driven by conservation and technological innovation spurred by the rising price of water (neoliberalism wins again, you might say).
Here's how California's water market has responded to drought conditions between 2009 and 2018 (all prices are per acre-foot, in real 2009 dollars using the CPI—All Urban Consumers Average from the BLS) [1]
The reduction in water usage was not limited to the agricultural sector. Indeed, despite California's population growing from 34 million in 2001 to 39 million in 2015, urban sector water usage declined by 1%, "primarily due to efficiency and conservation measures." [1] And municipalities comprise roughly 55% of the demand-side market share in the water market.
Can California grow without using more water?
Based on the performance of the water market, conservation efforts, and technological innovation the answer is a clear yes. But we will have to change how we grow our urban centers and where growth is located to make that growth sustainable.
Urban water usage is primarily affected by two things: climate and density. San Francisco, with the coolest climate and highest density in the state, uses the least water -- a paltry 44 gallons of water per person per day. Sacramento, with its hot and dry climate and sprawling land use patterns uses over 100 gallons per person per day. For every one person that moves to Sacramento, two could have moved to San Francisco and still have used less water! Even Los Angeles is better than Sacramento, clocking in at 72 gallons per person per day.
Growth of low-density homes in rural and suburban areas is the worst way California can grow, but is tragically one of easiest ways to build -- both in cost & complexity of construction and ease of permitting. The California Environmental Quality Act (CEQA) ironically makes sprawling, car-dependent development easy, and dense infill development incredibly difficult and expensive. California must reform CEQA to match the reality we now live in: suburban sprawl both consumes far too much water and causes literal tons of extra CO2 emissions from cars.
Facilitating this growth will mean surmounting NIMBY opposition based on water shortage fear mongering. The Burlingame Voice, a blog purporting to be a newspaper, showcases the typical talking points, both in their blog posts:
Someone other than me asked [Senator Scott] Weiner where all the water will come from? He responded that “we have a structural deficiency” on water infrastructure and then made the ridiculous claim that “building housing doesn’t drive population growth” or water consumption. He really said that. After the obligatory comments on low-flow toilets and water reuse (“we are way behind Australia and Israel”), one was left to wonder how he would keep the middle-class in California without consuming more water. It must be nice to live in the fairyland of the state senate and not have to worry about fixing “structural deficiencies” before plunging ahead with massive growth laws.
https://www.burlingamevoice.com/2019/06/scott-weiner-comes-to-burlingame.html#comments
And in their comment sections:
I was invited to attended a zoom water meeting today by our State Senator Josh Becker. I responded and asked this question, "Why are there still state mandated housing requirements, if there is not enough water for current residents?"
- User "Paloma Ave" in the Burlingame Voice comments section
This kind of thinking is widespread among the old-guard anti-growth environmentalists that control California Democratic politics. It's a rejection of basic facts in favor of aesthetic pastoralism that only allows the most wasteful urban development patterns.
Landscaping "makes up roughly half of all urban water use", which is one reason that dense infill development uses water so much more parsimoniously. A house on a quarter acre with a lawn in Sacramento uses more water to keep some plants alive than a single human being uses for all of their needs in San Francisco.
In order to grow California, we have to move beyond suburbs and faux-environmentalism that calls sprawling, remote, luxurious mansions "sustainable" just because they look rustic. The most sustainable development is a brand new apartment in a skyscraper outfitted with low-flow water fixtures and no yard that's near high quality public transit and within walking or biking distance to work, school, and recreation.
California has plenty of water to grow, but we lack the political will to make it possible.
Schwabe K, Nemati M, Landry C, Zimmerman G. Water Markets in the Western United States: Trends and Opportunities. Water. 2020; 12(1):233. https://doi.org/10.3390/w12010233