LOS ANGELES–The U.S. Army Corps of Engineers Los Angeles District issued a $1.47 million task order Sept. 1 under an existing contract to BJD Services of Santa Clarita, California, for strategic in-channel, non-native vegetation, trash and debris removal in the Los Angeles River in the area downstream of the Ventura Freeway Bridge in Glendale to Shoredale Avenue in Elysian Valley.
The Corps conducted a review of existing conditions of the flood risk management systems it oversees last fall. In total, 11 dams, one debris basin and more than 55 miles of channel within the Southern California region were evaluated.
The review resulted in the placement of interim risk reduction measures, specifically temporary barriers, to establish a consistent flow rate, or conveyance capacity, along Corps operated and maintained reaches of the Los Angeles River. The Corps has identified measures for channelized areas along the Los Angeles River from approximately Griffith Park to Elysian Valley, including the Glendale Narrows area, which pose the greatest risk of flooding to adjacent communities during large storm events. A combination of factors, including design capacity and the presence of vegetation growth and sediment accumulation, contributes to reduced water flow in these areas.
“A team of experts in several different disciplines determined that there is a need to remove non-native vegetation and debris to reduce the risk of potential outbreak,” said Lillian Doherty, Chief of Operations. “Limited federal resources for routine maintenance has resulted in overgrowth of vegetation and sediment accumulation that increases the risk of localized flooding.”
Non-native vegetation removal will take place in the areas identified to have the largest contingent of contiguous non-native vegetation growth. Passive recruitment will provide opportunities for native plants to re-establish and incidentally benefit the environment.
Work is anticipated to begin the week of Sept. 19.
An onsite biologist will identify non-native vegetation to be removed via cutting and/or managed via Environmental Protection Agency-approved foliar herbicide application treatments, as appropriate. Prior to any work occurring, the onsite biologist will identify the non-native vegetation targeted for removal.
The non-native plant cover in the project area is dominated by giant reed (Arundo donax), castor bean (Ricinus communis), and various palm tree species (Washingtonia robusta, Phoenix canariensis, etc.). These species, in addition to other identified non-native vegetation, will be specifically targeted for removal and follow-on treatment.
Nesting season vegetation removal would be limited to Arundo donax, Ricinus communis, and Washingtonia filifera, which are species that are fast-growing and could rapidly re-infest the channel and create additional flood hazards if year-round maintenance is not conducted.
No trees (except palm saplings) would be cut down during the nesting season, and potential nesting habitat would be delineated and avoided during the nesting season.
Cutting of non-native vegetation will be done using hand tools. Cutting of non-native species will not involve any soil disturbance. All root wads will be left in place. All cut non-native vegetation will be removed by hand from the channel.
Pick-up trucks or other rubber tired equipment will be used to haul loads of cut non-native vegetation to the nearest dumpster. All driving routes will be along the concrete toe or on top of the levee.
Dumpsters will be placed on top of the levee on barren ground or on the levee maintenance road. No cut vegetation or equipment will remain in the channel overnight.
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