As Californians slog their way through a third year of drought, they are being told to reduce their use of water.
In June, tough new state emergency drought rules were implemented. They prohibit the use of drinking water for irrigating “nonfunctional turf” at commercial, industrial and institutional properties. “Nonfunctional” means solely ornamental and not regularly used for recreational purposes, or community events.
This increase in water-use restrictions comes after state officials last summer imposed a voluntary plan to reduce Californian’s water use by 15 percent. Those voluntary efforts have widely missed the mark. Statewide water savings through March amounted to just 3.7 percent less than a 2020 baseline. And in March — an especially dry, warm month — use in cities and towns actually increased by nearly 19 percent.
“Every water agency across the state needs to take more aggressive actions to communicate about the drought emergency and implement conservation measures,” Gov. Gavin Newsom said in May during a meeting of local and state water officials.
He warned that if localized and voluntary conservation approaches do not result in a significant reduction in water use statewide this summer, the state could be forced to enact mandatory restrictions.
The city of Bakersfield and California Water Service, the area’s two major water providers, already limit the days and hours customers can water their outdoor landscaping. City customers with odd-numbered addresses are allowed to water outdoor landscaping from 6 to 9 pm on Tuesdays, Thursdays and Saturdays. Even-numbered addresses may water on Wednesdays, Fridays and Sundays.
Cal Water customers with odd-numbered addresses may water from 6 pm to 8 am on Tuesdays and Fridays, while even-numbered addresses may water on Wednesdays and Sundays.
The tougher new state emergency rules do not apply to yards at individual homes. Sports fields, grassy areas where people gather and watering to keep trees healthy are exempt.
The public’s potential overreaction to these new restrictions and the potential harm that could be caused to trees have arborists concerned.
Even with watering days and hours restricted, local landscapers insist landscaping can be adequately maintained if sprinklers are properly adjusted and irrigation is done in short durations that allow water to soak into the ground. But improperly or inadequately watering can permanently damage and even destroy trees.
“Trees need water for moving nutrients to leaves and for metabolic processes,” explained John Karlik, environmental horticulture adviser with the University of California’s cooperative extension in Kern County. “Trees have limited capacity to adjust to prolonged dry conditions. In other words, trees cannot ‘acclimate’ to prolonged drought, and the larger the tree, the more water it needs.
“Lack of water will predispose trees to attack from boring insects — Pacific flatheaded borer, carpenter moth, or others depending on the tree species. Leaf fall and brown margins of leaves can indicate water stress.
“Fortunately, trees can draw water from a large soil volume,” he said. “Roots typically extend to the canopy dripline and often beyond, but most roots are found in the upper three feet of soil, with the greatest percentage in the upper foot. Periodic (two to four weeks) deep irrigations for shade trees can be helpful.”
“A lot of people think trees are going to be real water users. They actually are not, if you plant the right ones,” said Lindsay Ono, a professor of ornamental horticulture and plant sciences at Bakersfield College.
Local landscapers can recommend appropriate trees for Bakersfield’s arid and often hot climate. For example, Monji Landscaping company posts a listing, with explanation, of its top six Bakersfield shade trees on its website monjilandscape.com. These trees, starting with the company’s number one choice, include Chinese Flame, California Pepper, California Sycamore, Flowering Pear, Cork Oak and Palo Verde.
But some California “native plants,” including trees, may not work well in Bakersfield, said Karlik.
“Note that Coast Redwoods are native in Mendocino County and Santa Cruz area. But these trees are poorly adapted in Bakersfield. ‘Friends don’t let friends plant Redwoods’ is my saying,” he said. “All plants are native somewhere. But how that area compares to our local conditions is to be considered.” he said.
“Trees that cool the house can save energy,” Ono noted. “If they are strategically located in the yard, they will cool the soil down and you can conserve water in that fashion, as well. Trees are very important.”
The California Urban Forest Council at caufc.org advises to water landscaping early in the morning, or after the sun has set, when plants and trees replace the water lost during the day. The timing also reduces evaporation. The organization offers the following watering tips:
Year 1 and 2: Five gallons of water, one time a week. Water the area under the dripline — the area under the farthest reaches of the branches.
Year 3: 10 gallons, one time every two weeks.
If the weather is hot and the soil dry, give the tree an extra five gallons.
Mature trees, after 3 years: Water deeply within the dripline, when the top six inches of soil around the tree has dried out.
Avoid planting water-loving groundcovers. Mulching around trees and other plants reduces water evaporation and makes for an attractive water-wise groundcover.