Stormwater Engineering Projects

Picture of Big Tujunga Wash Mitigation Area



Please be aware that maintenance activities will be conducted throughout the Big Tujunga Wash Mitigation Area (Mitigation Area) through December 2024. This work is being performed by Chambers Group, an environmental consulting firm, under supervision of Los Angeles County Public Works (Public Works). To protect native habitat that supports threatened, endangered, and special status species on site and to promote public safety and enjoyment of Big T, work crews will be conducting trails clearing and maintenance, invasive wildlife maintenance, and invasive plant removal.

Invasive plants will be removed using mechanical methods (such as hand-pulling, digging, and weed-whacking) and County-approved herbicides. This integrated approach will allow for more effective removal, particularly when it comes to controlling invasive grasses (that can increase fire danger) and deep-rooted perennials that continue to resprout unless the full root structure is removed. Hand removal of these invasive perennial plants is labor intensive and often less effective than targeted herbicide treatments. All herbicide treatments will be conducted under the supervision and guidance of licensed biologists and restoration technicians, who are trained to use herbicides in a safe manner with respect for the environment, wildlife, and human health. Only select California-approved herbicides that are known to be safe for the environment will be used. Only California aquatically approved herbicides will be used within 15 feet of waterways. No herbicides will be used during high winds or rain to prevent herbicide drift and runoff. Glyphosate (Roundup®) will not be used during maintenance efforts.

Vegetation trimming and removal will continue as necessary in the southern portions of the Mitigation Area to improve public safety.

Crews will respond, as needed, to any trail issues that may arise. Crews generally will work between 7 a.m. and 4 p.m., Monday through Friday. No work will be conducted on the weekends.

Please be aware that planned maintenance activities at the Tujunga Ponds may involve the use of small (non-mechanized) boats, fishing nets, rods and reels and other equipment that is not authorized for public use within the Mitigation Area. This equipment is authorized by Public Works to help facilitate specific maintenance tasks. Work crews will also conduct invasive wildlife maintenance within Haines Canyon Creek. If you are uncertain whether observed activities in the Creek or Ponds are authorized maintenance, please contact Public Works. No fishing, swimming, wading, damming of the Creek or other disturbances are permitted in the Mitigation Area.

Trapping of the parasitic brown-headed cowbird will be conducted between April 1 and June 30. During this period, you may see the brown-headed cowbird traps onsite. Please, do not approach or tamper with the traps. The traps are maintained and serviced daily to provide fresh food and water to any birds inside. Brown-headed cowbird trapping is critical to help protect sensitive songbird species such as the least Bell’s vireo.

Least Bell’s vireo, a federal- and state-listed endangered species, were observed nesting in the Mitigation Area in 2020 and were detected in the Mitigation Area in 2021, 2022, and 2023; this was the first time least Bell’s vireo has been documented onsite and nesting since the inception of the Mitigation Area. Please help protect the least Bell’s vireo and other sensitive species by staying on authorized trails and keeping companion animals leashed so that they do not wander into habitat areas where birds may be nesting.

There will be bilingual Chambers Group biologists onsite during peak-use weekends this summer. Onsite biologists are happy to provide educational information and answer questions about the Mitigation Area. The biologists value user ideas and concerns and would love to hear from you!

Please be watchful when riding horses or hiking where maintenance crews are working. It is recommended to avoid active work areas whenever possible, but if you do come upon a crew, please call out to them if they do not see you so they can stop their equipment and allow you to pass by safely.

The Community Advisory Committee (CAC) meeting is tentatively planned for Spring 2024 and will be held virtually. Further details will be posted and distributed when available.

The Annual Trail Cleanup Day is tentatively planned to occur in Fall 2024.

Experts at Chambers Group monitor all maintenance activities to ensure that sensitive biological resources are not negatively impacted during maintenance activities. If you have any questions regarding planned maintenance activities, please contact Public Works at


The Big Tujunga Wash Mitigation Area was purchased by the Los Angeles County Flood Control District in 1998 to compensate for habitat loss from other projects. The site encompasses approximately 210 acres of land located in the City of Los Angeles-Sunland area.

For nearly two decades the Mitigation Area's native alluvial scrub, cottonwood-willow riparian, and oak-sycamore woodland plant communities accommodated miles of winding equestrian and hiking trails and provided suitable or potential habitat for a number of endangered, threatened, and sensitive plant and wildlife species including Davidson's bushmallow, Plummer's mariposa lily, slender-horned spineflower, San Diego horned lizard, black-crowned night heron, great blue heron, Cooper's hawk, loggerhead shrike, southwestern willow flycatcher, least Bell's vireo, and Santa Ana sucker.

In December of 2017, the Creek Fire burned through the Mitigation Area, leaving these plant communities severely fire-damaged or destroyed. While goals for the Mitigation Area ultimately remain the same, the plans to reach those goals were revised in 2018, shifting from a highly maintenance-based approach to one of restoration and maintenance.

The Creek Fire, while devastating to the Mitigation Area, has provided a wealth of opportunity to reestablish trails and restore habitat function that is essential for sensitive wildlife species to thrive. During the Mitigation Area's recovery process, implementation efforts will focus heavily on invasive plant and wildlife removal in order to support the return of native habitat and wildlife to the Mitigation Area.

Big Tujunga Wash Mitigation Area



For more information on the project or to report minor incident, please contact or phone the LA County Sheriff at (800) 834-0064.

Updated on: 02/08/2024