First the good news: Palo Alto has done a great job in its water conservation efforts, and through its diligence, the community has cut water usage more than 33 percent compared to 2013 levels. Now the not so great news: all that water conservation may be impacting the City's trees, which are showing signs of stress. While property owners are required to reduce water consumption, it is important to maintain the health of our urban canopy. Trees are the most valuable element of the community’s green infrastructure, long-lived and beneficial for health, climate change and overall quality of life. During times of drought, smart tree watering is a good investment.
It’s important to know what to look for to determine if a tree is stressed for water. Trees may be more prone to branch failure, root dieback and insect or disease problems. Check trees for symptoms of stress such as early browning or dropping of leaves, excessive branch drop (noticeably more than usual), wilting and cracks in the bark.
There are a number of ways to maximize the impact of watering trees while minimizing water waste. First, different trees have different water needs so it’s important to determine how much and how often to water them. That can be done by looking at the tree species, age, health and conditions of where it is planted. When watering, it is best to hand-water or use drip irrigation to establish young trees. Avoid sprinklers and spray irrigation, as these methods are least likely to deliver water where the trees can best use it, and can waste water through overspray, evaporation and misting. Water gradually and deeply, applying water slowly and evenly to the tree’s root zone. Mature trees can be watered once a month or when the soil is dry at 12 inches below the surface. Mulch with wood chips two to four inches deep to insulate the tree roots from extreme temperatures.
The City provides many helpful resources, including a Save our Water and Our Trees brochure, free workshops on tree care during a drought, links to other information and expert advice on the City’s Water and Drought webpage. Canopy has a great online Tree Library to help you select drought resistant trees before planting. Visit their website for watering instructions, tree care guides, and more.
More assistance is available on a special limited time basis. Contact Palo Alto’s Urban Forestry Section through PaloAlto311, email Public Works Public Services at email@example.com, or call (650) 496-5953 to submit a tree care request for a free health screening of any publicly-owned street tree or park tree, request one-time watering, or addition of mulch.
Palo Alto must reach a cumulative 24 percent water use reduction for the period of June 1, 2015 through February 28, 2016. Right now, the City is on track to meet this target, but is reminding residents and businesses that conservation efforts must continue through the winter to enable the City to meet its state-mandated goal. For more about current drought conditions and Palo Alto’s water use restrictions, visit cityofpaloalto.org/water.