Planting Trees to Save Water

After graduate school, I wanted to explore the world beyond water. So last summer, I interned at Urban Releaf, a tree-planting nonprofit - only to wander right back into the water world. A project I was involved in would demonstrate how street trees in urban areas can play a part in conserving water in the current drought in California, and filter pollutants in storm water before it enters the Bay. (Big asterisk here, read on to read why.) Working with a water scientist from UC Davis, Urban Releaf designed a "green street" pilot project in a West Oakland neighborhood.

This is the block in question, on 31st Street and Market. As you can see, there are no trees, all concrete. And somehow, both rows of houses have high fencing. Kemba Shakur knows the neighborhood, and said one side is almost completely African-American, the other Asian-American. This is the second time she's here when the cops are here. What is the role of trees in creating a socially harmonious environment?

















The purpose of the project would be to plant trees, first and foremost. After all, everyone deserves nice trees where they live. Scientists say trees bring psychological benefits, and just being able to see trees out the window can calm us down. Looking at an aerial photo of West Oakland (below left) - that area by the port bounded by the 580, 980, and 880 freeways - tree canopy cover is a dearth compared to other neighborhoods. For example, here's my neighborhood in Berkeley (below right).

















This is an example of environmental injustice, and Kemba and Urban Releaf is working hard to address that by planting trees in urban areas that have disproportionately fewer trees. These are not only usually lower-income communities, but also communities of color.

The project won a 2-year grant from the Department of Water Resources to help urban areas adapt to drought conditions in California. Not only would the trees provide shade and make walking more comfortable for residents of this street, they would also need less watering thanks to specially designed tree wells. The wells capture rain water, which the trees in turn use for growth.

Another way the trees and tree wells would save water is by reducing pollution in the Bay. Think about what happens under normal urban circumstances - when it rains, water flows into the storm drain, carrying with it leaves, plastic bottles, food wrappers, and other trash, as well as the grime our cars leave behind on streets, before making its way to the Bay through our cities' networks of creeks and underground storm drains.

In a more natural environment like a forest or a park, with less of the surface covered by hard pavement, water soaks into the soil, which in turn filters out pollutants from the water before it joins a creek or storm drain. Capturing storm water in tree wells mimics this filtering out process so the water entering the Bay is a little bit cleaner.

Green streets are part of a suite of Low-Impact Design techniques that have seen rising popularity in cities like San Francisco and Portland. Low-Impact Design minimizes the negative impacts of our paved, urban world on our waters. It slows down the flow of urban runoff, puts less pressure on our cities' storm drain systems, and reduces the amount of pollutants entering our Bay.

Just how effective are trees and low-impact design in saving water? An integral part of Urban Releaf's green street project is keeping tabs on the numbers. Urban Releaf staff, Jaimini Parekh, and Jamal and Hakim Davis, helped UC Davis scientist Qingfu Xiao install a water meter in the storm drain at the corner of 31st and Market. After picking out the trash that has collected there - trash that would have found its way into the Bay, in goes the meter. The meter would measure how much water ends up in the storm drain, before and after the trees are planted. That way, we would know how much water is captured in the special tree wells.




















































If you noticed the tone of this entry is rather tentative. The project is facing uncertainties. With the economic crisis, the state ordered people to stop work on water projects that are funded by bonds, including from Propositions 50 and 84 which funded this project. Many of our colleagues in the water world are feeling the effects of this stop-work order and have had to lay off their workers or fold completely. Some nonprofits doing awesome environmental work, like Urban Releaf, survive on state funding. Read more and sign an online petition here.