For 100 Years, Humans Made Southern California Green. Now, the Drought Is Returning Our Landscape to Its Rightful Color Palette.
The following article is written by Dr. Pincetl and posted on Zócalo Public Square.
Droughts in California are always seen as exceptional, even though they are common events, part of our natural climate pattern. So will our state really be changed by the current drought? And if so, what will our familiar landscapes look like as a result?
The answer may be that we are going back to our drier, browner–and more colorful–past.
I have spent the past few decades studying California and how humans have transformed its landscapes, including the state’s water resources. I have been analyzing water use in the city of Los Angeles with Terri Hogue, a hydrologist at the Colorado School of Mines, and Diane Pataki, an urban ecologist at the University of Utah. We map residential water use and focus on what’s called the “water balance” of L.A. County: how much native water exists in L.A. County, and how we use the water we import.
Today, we may be emerging from a relatively wet period, a mild century in terms of droughts. During this period, California also built an extraordinary water infrastructure. The California State Water Project moves water north to south and east to west. L.A.’s water comes from Oroville Dam (over 400 miles away, conveyed through the Delta), the Colorado River another 400 miles away, and the Owens Valley. The result: In the last 100 years, humans have made California’s landscape much greener.
These multiple sources of water seemed like good insurance but unfortunately, except for parts of the Colorado River watershed, each one is suffering from drought. In fact, the Metropolitan Water District of Southern California projects that the existing water supplies it stores in its Diamond Lake reservoir will only last Southern California for a year–and only if water restrictions are put in place.
Of course, water restrictions are not new. After the drought in the 1970s, the Los Angeles Department of Water and Power (LADWP) launched a major effort to reduce citywide water usage. Today, L.A. has 1 million more people than it did 40 years ago but does not use more overall water. This was accomplished largely through low-flush toilet replacement, from 8 gallons a flush to 2.5 gallons a flush. The 2009 drought also ushered in mandatory outdoor watering restrictions to two days a week, resulting in a 23 percent water use reduction, but these were relaxed after the state received better rainfall.
Today, per capita residential water usage is about 130 gallons per day in L.A. If there is no rain by January, each household may get a water budget, and outdoor watering may be limited to just one day a week. In that case, the smart choice for Angelenos will be to water trees and bushes, but not lawns or annuals. This would be a dramatic and drastic first step toward shifting to a more climate-appropriate landscaping in L.A., where outdoor residential irrigation accounts for over 50 percent of residential water use.
Another year or two of drought will greatly accelerate the change to a browner landscape. This shift should have occurred in the decades since the drought in the ’70s, but people are reluctant to give up their lawns and lush outdoor landscaping. The mandatory outdoor watering restrictions put in place during the 2009 drought did not actually impact greenness, as my colleagues and I discovered using satellite imagery. In non-restrictive periods, too much water is applied to the landscape, resulting in runoff and sustaining vegetation better suited to places with year-round precipitation, like Seattle. We also found that, as soon as the restrictions were lifted, people went right back to over-watering.
If we dramatically reduced our outdoor water use, it would allow us to make our scarce resources last through another year or so of drought. This is especially critical in wealthier neighborhoods, which use up to three times more water than less affluent neighborhoods. Yes, they have big lots, and that is the point. Less water used on those big lots means more indoor water for everyone, and for a longer period of time going forward.
Thanks to the drought, the subtle range of browns, blonds, and gray-greens that once characterized the region’s seasonal shift into late summer and fall will return and link us more closely to the place where we live–a water-short region in which even a sprinkle of winter rain can awaken new growth. In years when there is no rain, the plants hunker down and shrink, waiting patiently for a better year. Seeds wait for the rains to return to germinate, some of which are able to wait for years.
Before long, the drought will bring that brown back after a hiatus of about 100 years of human transformation of California’s landscape. Those broad swaths of lawn in traffic medians–think Beverly Hills and Pacific Palisades–will be replaced by decomposed granite, oaks, olive trees, yellow flowering Palo Verdes, and pink flowering Redbuds. Yes, the state will be more colorful. Drought-resistant and drought-tolerant shrubs, flowering bushes, bulbs, and tubers will provide an extraordinary new palette of colors, shapes, and textures.
Rural areas could change along with cities. The drought will force us to ask hard questions like: Are urban dwellers entitled to a full 20 percent of the state’s water when agriculture uses 80 percent? Currently neither cities nor farmers get the full amount they are allotted, and there is wasteful behavior in both urban and agricultural uses. But agriculture produces our food, and importing what we eat from somewhere else has consequences, too.
We need to be thoughtful about our water and to remember our interdependence. There is enough of it to meet our needs, but we can no longer be wasteful. And we can no longer segregate water into categories like freshwater and wastewater. There is just one category of water, and recapturing our wastewater increases our available resources, ensuring the fullest use of what we have locally and what we import.