Oct. 1, 2013
The Ojai Valley stands to lose one to five percent of its trees if the valley’s water issues aren’t addressed very soon, according to one local arborist.
One of the critical issues, however, is not within anyone’s ability to control — we need rain.
“I’m telling everyone to pray for rain,” noted landscape architect and arborist Tom Bostrom. “Our oak trees are dying. They are severely stressed. We need rain desperately.”
Two other factors that are within human control are how valley residents irrigate their landscape and how many wells can tap the Ojai basin’s ground water and how much water those well owners should be allowed to extract.
“These two drought periods we have gone through recently and having more straws sucking the water out of the ground have changed the hydrology of the valley,” Bostrom explained.
Lake Casitas is currently at 63.5 percent of its capacity and has become the primary source of water for the entire valley as local water companies have all seen their wells run dry and are now buying much of their water from the Casitas Municipal Water District (CMWD).
Bostrom said the rapidly falling water table and lack of rain means trees in the valley, including its signature oaks, will likely need some help.
“People often hear ‘don’t water oak trees,’ well yeah, don’t water oak trees around their base, but right now many of them need water desperately,” said Bostrom. “When they are severally stressed like this, water is only thing that is going to help.”
But Bostrom’s advice comes with a caveat. “People look at the leaves on a tree and figure if they’re turning brown then it must need water,” he noted. This is not always the case.
“The first thing people need to do is to get to know the ground,” he explained. “Poke around under the drip line and see if the ground is wet. Maybe it’s getting too much water.”
He said this can happen when trees are too close to landscaped areas, such as lawns that are watered regularly.
Bostrom uses the valley oak at Montgomery Street and Grand Avenue as one example. Surrounded by asphalt and sidewalk to its base, the tree’s roots would appear to have a limited capacity to absorb water. He said the tree’s structural roots are located within the top 2 or 3 feet of soil closest to the base, but the roots that collect a mature tree’s water are typically closer to the edge of the canopy. Which is why, he said, this tree is doing moderately well during the current drought — it is receiving moisture from nearby lawns.
If the ground truly is dry, he recommends placing a soaker hose nearer to the drip line of the tree (the farthest edge of the canopy) and slowly, so there is no runoff, soaking the ground until it is wet to a depth of about six to 12 inches. Then, he said, don’t water the tree again until the ground in that area has dried again completely. Keeping the soil wet under a tree’s dripline constantly encourages organisms to attack the structural roots and invites decay.
Some trees, including the valley’s sycamores, are turning brown as part of their natural winter cycle. While cold usually triggers this seasonal change, he said the lack of moisture is likely hurrying the process this year. He recommends using the same dry soil watering guidelines when determining whether this type of tree needs supplemental watering.
Bostrom said education is key to conserving water until enough rain returns to the area to recharge the basin. Alongside that, he noted, governmental regulations will likely increase.
One example, he said, is the state-mandated landscape ordinance the city is currently working to implement. Under the ordinance, which has still not been adopted by Ventura County officials, commercial and residential property owners proposing landscape projects of 2,500 square feet or larger, will be required to submit landscape architect-approved plans showing details of the proposal, including how much water it is expected to consume, the type of irrigation system and the types and numbers of plants.
Additionally, he said, a discussion will likely have to be posed regarding the number of wells residents are allowed to sink into the Ojai Basin and how much water they are allowed to extract.
Currently, the Ojai Basin Groundwater Management Agency, a group comprised of a representative from the city of Ojai, CMWD, Golden State Water Company, the Ojai Water Conservation District and Mutual Water Companies, is tasked with protecting the groundwater in the Ojai Basin. Although it requires that all wells within the basin be registered and that owners report their extraction amounts, enforcement of these guidelines have been difficult due to limited staff and resources.
Editor’s note: This story was modified on Oct. 3 at 2:38 p.m.