Public Works Begins Revegetating Process to Compensate for Bulldozed Trees

By Jim E. Winburn

The County of Los Angeles Department of Public Works is currently involved in a revegetation project for the Santa Anita Dam flood control facility to create an oak woodland habitat as part of a mitigation process for removing 11 acres of trees a year and a half ago.
Since cutting down nearly 180 coastal oaks and 70 sycamores from the flood control facility in Arcadia on Jan. 12, 2011, Public Works has removed approximately 330,000 cubic yards of sediment from the dam. The removal of material from behind the dam and the storage of this sediment on placement sites downstream has all been part of the 1927 dam’s riser modification and seismic upgrade process to meet state standards.
According to Public Works representative Keith Lilley, the bulldozing of the woodland area in the middle sediment placement site was necessary for the current projects underway. “Without this Middle SPS, there would not be the capacity for future sediment placement from either emergency or planned sediment removal projects from the facilities served by the Santa Anita SPS,” Lilley explained.
The mitigation process, which obligates the county to restore portions of nearby property for flood control projects that impact local habitats, will provide planting, irrigation and biological monitoring for the Lower SPS. The cost for developing this oak woodland habitat is $650,000, according to Lilley.
To develop the revegetation plan for the Lower SPS and conduct the required seed collection, the county has contracted with Pasadena-based BonTerra Consulting, a team of biologists that includes environmental planners, botanists and arborists.
BonTerra already has conducted two years of native seed collection within the Santa Anita watershed, and this seed will be propagated this year in anticipation of plantings starting in fall 2013, Lilley said. In addition, the county is currently coordinating with the California Department of Fish and Game on final revegetation criteria, while working to secure a restoration contractor in spring 2013.
Michele Chimienti, a civil engineer for Public Works’ Water Resources Division, said that details down to the particular insects native to this area will be used to create a balanced ecosystem, demonstrating just how conscientious the state’s mitigation process is.
“And that’s what Fish and Game wanted,” Chimienti said. “They wanted to make sure that everything we’re planting here was from this local watershed; so we have our biological consultants that are collecting seeds from nearby.”
Lilley said the planting of the Lower SPS will begin in fall 2013, but the majority of plantings will be in fall 2014 after the seeds have grown into small plants suitable for transplanting on site. In the interim, the site will be planted with grasses to prevent erosion.
The plantings will be monitored closely by biologists per the revegetation plan for the next 7-10 years to ensure all criteria is met, according to Lilley. And after that the site will be preserved as an oak woodland habitat.
Lilley also noted that, as an additional project, the county has already purchased and permanently protected with a conservation easement 4.9 acres of mature oak woodland habitat in the tributary watershed adjacent to the project site.
In the meantime, the county anticipates that the sediment contractor, who is removing the final dirt from behind the dam, will finish up within the first week of October. Storm season normally begins Oct. 15, and flood control personnel are preparing for the upcoming 2012-13 El Nino storm season.

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