September 20, 2021

Roadside Committee Moves Forward with Mapping


The Topanga Canyon Boulevard Roadside Committee (TCBRC) presented detailed maps and identified vegetation along the boulevard as it moved forward on Dec. 12 in an effort to eliminate the use of any herbicides along Topanga Canyon Boulevard. The Committee is committed to maintaining the integrity of the ecological diversity that thrives along the roadside from wet habitat, wildlife trails, native plants and a spring that runs alongside the boulevard and supports stream orchids.


To further strengthen the abatement plan, Rosi Dagit, Senior Conservation Biologist for the Resource Conservation District, suggested during the summer that the group map sensitive roadside areas along the northern portion of Topanga Canyon Boulevard to determine best use practices for mechanical brush clearance and weed abatement.

According to Dagit, the purpose of the mapping is to identify all the “constituents” within the scope of the defined roadway—types of vegetation; proximity to natural waterways (creeks, streams, drainage culverts); geographical terrain/conditions (downslope, upslope, wide shoulder, narrow shoulder, no shoulder, straight, curvy, uphill, downhill); distances; locations; utilities; types of infrastructure (guardrails, road signage, hydrants, turnouts)—that are in the State’s/Caltrans’ right-of-way, as well as within their eight-foot area of responsibility to maintain and keep roadsides clear.

By virtue of Federal Executive Order, there is a variety of safety and environmental reasons, among them vegetation management that rids the roadsides of invasive plants in order to support the health of the native environment.

Contributing to the mapping was Irina Irvine, Ph.D., Restoration Ecologist for the Santa Monica Mountains National Recreation Area and the National Park Service plant team who conducted a preliminary mapping in early December to provide a starting point and an up-to-date idea of what kinds of vegetation are found in the section of the boulevard from the town center north to Mulholland Drive.

During the meeting, the Mapping Subcommittee’s Roger Pugliese of TASC and Ed Siribohdi of CalTrans, presented the mapping results in a PowerPoint presentation.

Members of the Roadside committee were impressed with how detailed the maps were and how they “drilled down” to the basic elements of what is actually on the roadside.

“We are going to have to identify the best practices for every section of the roadside,” said Susan Nissman, Senior Deputy to L.A. Supervisor Zev Yaroslavsky. “That will lead us to developing a living, sustainable plan to manage the roadside vegetation without the use of herbicides.”

Overall, Nissman expressed approval that the maps “narrowed” down the roadside weed, fire hazard and abatement issues to a manageable level.


After the mapping presentation, Caltrans presented a roadside vegetation list of 47 plants identified as Native, Alien, Invasive and Flammable. The list broke out the native plants that would be saved from removal versus the non-natives that would be identified for manual roadside clearance.

While some on the committee felt it would be more helpful to focus on the specific plants that cause major problems along the roadside, regardless of their status, Dagit explained that “This is to focus on the big, bad boys, the ones that spread and do bad things,” Dagit said.


The ad hoc committee consists of community leaders from local organizations, including the Topanga Creek Watershed Committee (TCWC), the Topanga Association for a Scenic Community (TASC), Topanga Chamber of Commerce (TCOC), Topanga Canyon Town Council (TCTC) and the Topanga Coalition for Emergency Preparedness (T-CEP) along with the Resource Conservation District of the Santa Monica Mountains (RCDSMM), the Los Angeles County Fire Department/Fire Prevention Division and the State Department of Transportation (Caltrans) that owns and operates State Route 27.

The TCBRC has agreed to an April 2013 deadline for a definitive plan with Caltrans.