The Santa Margarita River is one of the last free flowing rivers in Southern California. The river drains an arid region at the southern end of the Santa Ana Mountains, flowing 29 miles through natural riparian vegetation, eventually passing through the U.S. Marine Corps base at Camp Pendleton and thence to the Pacific Ocean. The Santa Margarita River historically supported large runs of Southern steelhead (Oncorhynchus mykiss). However, due to urbanization and fish passage barriers, steelhead have been prevented from accessing the upper river reaches that contain prime spawning and rearing habitat.
After years of design, construction is now underway to remove the last remaining barrier to endangered Southern steelhead migration in the Santa Margarita River. This project led by CalTrout will remove the aging and flood-prone crossing at Sandia Creek Drive (left panel below) and replace it with a new 574 ft. steel bridge just downstream. The existing bridge—in the middle of a scenic wildlife corridor and the popular Santa Margarita Trail Preserve, owned and managed by the Wildlands Conservancy—also presents a safety issue for commuters traveling on Sandia Creek Drive during heavy rains when the bridge becomes completely submerged (right panel below).
CalTrout raised $18 million in grant funding over the past two years from state agencies including the California Department of Fish and Wildlife, Wildlife Conservation Board, California Natural Resources Agency, and State Coastal Conservancy to support the fish passage removal project and enhance this critical wildlife corridor. Our most recent award for $3.2 million came from the National Oceanic and Atmospheric Administration (NOAA) which will help fund construction tasks, and also the development of a locally trained and employed Climate Crew to maintain the lands of this pristine watershed in Southern California as restoration and construction goes on. The new bridge, designed with coastal resilience in mind, will allow 100- year flood flows to pass beneath it and will improve traffic flow and safety for trail users.
As one of the few perennial rivers in Southern California, restoration of the Santa Margarita River offers a prime opportunity to recover the endangered, yet resilient Southern steelhead. The river still has natural channel characteristics necessary for migration and propagation of the species and has been designated as high priority for recovery as outlined in the National Marine Fisheries Service (part of NOAA) federal recovery plan for Southern steelhead. Thus clearing the vegetation for construction has been carefully mapped out to minimize impacts. In the image below it is not visible from an upper trail.
But behind those trees just downstream of the existing box culvert crossing is the fully cleared path for the new 574 ft steel bridge, looking from the north (below left panel) and south (below right panel) sides of the river channel.
This takes some strong horse power from big machinery to clear the path, but the revegetation plan is already in place to restore vegetation in this sensitive riverine corridor once the new bridge is completed.
The Santa Margarita River-Sandia Creek Drive Bridge Replacement Project will eliminate the last remaining barrier to migrating anadromous fish, restore the natural hydrology of the river, and provide safer vehicle access across the river during large winter storms. During construction it is our priority to provide safe passage for trail users. To assist with public safety, new crossing lights for the connector trail system have been installed (below left panel), and the California Conservation Corps (CCC) constructed a by-pass trail (below right panel) to be used while the new bridge crossing the Santa Margarita River is being built.
This is a unique opportunity to restore fish passage from ocean to headwaters in a Southern California river. The bridge will be completed in May 2024, at which time the existing river crossing box culvert will be removed. The County of San Diego reviewed the plans and will own the bridge after construction.
Partners: The Wildlands Conservancy (landowner), County of San Diego, Pechanga Band of Indians, Fallbrook Trails Council.
Project Team: Granite Construction (General Contractor), Stinger Bridge and Iron (Steel Fabricators/Erectors), Gannett Fleming (Construction Manager), KPFF (bridge designer), River Focus (hydraulic engineering), Leighton (Geotechnical engineering), Dudek (permitting), The Pechanga Cultural Division (Tribal Monitoring)
We thank the Fallbrook Community for Input During this Process. CalTrout gave many presentations and publications as information on upcoming events:
Village News, Jan. 30, 2023, "Sandia Creek Drive bridge construction starts over the Santa Margarita River"
Fallbrook Planning Group, Jan. 26, 2023, Facebook post
County of San Diego, Jan. 6, 2022, Sandia Creek Drive Bridge Replacement and Fish Passage Project - CEQA and public comment notice
EverythingFallbrook.org, Oct. 20, 2021, "New bridge on Sandia Creek Drive — coming next Fall"
Village News, Feb. 21, 2020, "California Trout receives new grants to support recovery of steelhead and native trout in Southern California"
Village News, Feb. 15, 2019, "Preliminary work for new Sandia Creek Drive bridge is starting"