MALIBU CREEK ECOSYSTEM RESTORATION

The U.S. Army Corps of Engineers (USACE) and the California Department of Parks and Recreation (DPR) are jointly proposing a project to restore the Malibu Creek Ecosystem to a healthy, connected watershed that would improve beach nourishment and shoreline protection, and improve public safety.

 

This effort includes a detailed scientific study to determine the ecosystem restoration opportunities within the lower Malibu Creek watershed. The process will generate alternatives for ecosystem restoration, which consider removal of Rindge Dam and additional human-made structures located upstream within the Malibu Creek watershed.

Rindge Dam is located on Malibu Creek in Malibu Creek State Park, three miles upstream from Surfrider Beach and the city of Malibu. This large dam is the “keystone” barrier within Malibu Creek, stopping the movement of endangered steelhead trout and other fish and wildlife species that require uninhibited movement through the watershed. Additionally, an estimated 780,000 cubic yards of sediment is trapped behind the dam, resulting in four miles of impaired waterways.

USACE, DPR, and more than 33 groups involved with the Technical Advisory Committee considered several dozen possible alternatives for the restoration of the Malibu Creek Ecosystem and removal of Rindge Dam as a barrier to fish and wildlife.

The entities had two key goals when considering alternatives: 1) none would result in any increase in downstream flooding, and 2) materials behind the dam would be reused (recycled) as much as possible for the public benefit.

From this decade long effort, four feasible project alternatives have been identified. Public feedback will be solicited during the public review period to help identify the best alternative and options for future implementation. The proposed alternatives include:

Alternative 1 – No Project

Alternative 2 – Would remove the dam in approximately 20-foot lifts and truck the impounded sediment to the final disposal locations. Roughly 2/3 of the impounded sediment would be disposed of at the Calabasas Landfill, while 1/3 of the material that is beach compatible would be reused near the Malibu Pier, a historic receiving site. This alterative is anticipated to take 7-8 years to complete.

Alternative 3 – Would remove the dam in 5-foot lifts and allow the impounded sediment to wash downstream with natural storm cycles. This alternative would take 40-100 years and would require construction of downstream floodwalls in Malibu Lagoon State Beach.

Alternative 4 – The alternative is a hybrid of Alternatives 2 and 3. It would remove the dam in approximately 20-foot lifts and truck the impounded sediment as outlined in Alternative 2. It would also lower the dam five-feet at the end of each year to allow some natural transport of material during winter storms. This alternative would take 7-8 years and would require construction of downstream floodwalls in Malibu Lagoon State Beach.

Detailed information on the proposed project can be found online on USACE’s website.

The public is encouraged to provide comment on the Draft Integrated Feasibility Report. All comments must be received by March 27, 2017. Please address your comments to:

Eduardo T. Demesa
Chief, Planning Division
U.S. Army Corps of Engineers, Los Angeles District
ATTN: Mr. Jesse Ray (CESPL-PDR-L)
915 Wilshire Blvd., Suite 930
Los Angeles, California 90017

Phone: 213.452.3811 | Fax: 213.452.4204 | Email: Malibu.Creek@usace.army.mil

Documents are available on USACE’s website as well as at the following locations:

California Department of Parks and Recreation, Angeles District
1925 Las Virgenes Road, Calabasas, CA 91302-1909

Calabasas Library
200 Civic Center Way, Calabasas, CA 91302

Malibu Library
23519 West Civic Center Way, Malibu, CA 90265

A public hearing is scheduled Wednesday, March 1, 2017 from 6 to 8 p.m. at the Las Virgenes Municipal Water District located at 4232 Las Virgenes Road, Calabasas, CA 91302.

There are three key reasons why removing Rindge Dam and other smaller “in-stream” barriers is listed in the study as the preferred alternative to restore the ecosystem health of Malibu Creek watershed, quality of life for area residents and regional economy.

^{Southern steelhead trout (left) have access to only three miles of their 60+ miles of historic habitat in Malibu Creek watershed. Habitat for western pond turtle (right) and other species is impacted. (Courtesy of the Resource Conservation District of the Santa Monica Mountains)}

1. 1. Reconnecting Natural Waterways and Protecting Wildlife Corridors and Habitat
   Waterways are the life-blood of natural ecosystems. The study indicates that removal of in-stream barriers would reconnect the Malibu Creek corridor and restore riparian (creek/lagoon) habitat benefitting sensitive aquatic animals such as the endangered southern California steelhead trout, and protect animal movement corridors. By restoring Malibu Creek’s natural hydrology, the preferred alternative would protect the rare biological diversity present, and improve the related aesthetic, recreational and economic values.

   Additionally, Malibu Creek is a key wildlife linkage within the Santa Monica Mountains. Other important sensitive species use Malibu Creek for habitat and wildlife movement corridors. These include the least Bell’s vireo, western pond turtle, California red-legged frog, two-striped garter snake, Pacific tree frog, and mountain lion, among others.

^{Visualization of the dam halfway removed. Topography of the area behind the dam is currently artificially elevated 100 feet above the natural grade.
Roughly 780,000 cubic yards of material are trapped behind the dam, material that otherwise would move downstream to replenish beaches and surf breaks.
The impounded sediment extends almost one mile upstream (roughly to the roadway in the background). (Courtesy California State Parks, 2016).}

1. 2. Sand for Beaches, Stone for Surf Breaks
   Dams block natural sediment from moving downstream. Removing man-made barriers restores this natural cycle for beaches and nearshore habitats, and maximizes local reuse of sediments trapped behind the dam.

   An estimated 780,000 cubic yards of sediment is trapped behind the dam, resulting in unnatural creek morphology extending almost one mile upstream behind the dam. The harm on areas downstream of the dam extends three miles to the beach and beyond. The natural sediment cycle of boulders, cobble, and ultimately sand and silt moving downstream and onto area beaches and surf zones, has been blocked.

   Sediment starved beaches are shrinking as sand is carried away by surf and not replenished. This reduces natural barriers and protections for beachfront properties such as the historic Adamson House. The retreating sand requires costly artificial barriers, seawalls and repairs to protect beachfront property.

   Surfrider Beach, in particular, has been designated as a Beach Erosion Concern Area (BECA, 2010) for its lack of width/elevation to serve recreational demand and protect upland facilities. There are three simultaneous surf breaks at the world-famous Surfrider Beach, which receives an estimated 2.5 million visitors per year. Cobble, sand and other material washing downstream from Malibu Creek to form underwater bars are key to the area’s surf and the recreation it provides.

   The study outlines how removal of Rindge Dam would restore a more natural sediment cycle in the lower Malibu Creek watershed. Natural sediment flow benefits beaches, surf, and offshore environments, as well as the associated regional economy.

^{Eroding beach at Broad Beach (left) and repairing storm damage at the historic Adamson House (right) at the Surfrider Beach, 2012. Surfrider Beach, in particular, has been designated as a Beach Erosion Concern Area (BECA, 2010) for its lack of width/elevation to serve recreational demand and protect upland facilities. (Courtesy California State Parks, 2016)}

1. 3. Improve Public Safety
   The dam is an attractive nuisance for those who seek to jump from, climb on, or vandalize the dam. Despite the area being posted off-limits - enforceable by fines - and patrolled, thrill seekers still find their way to the dam. There is concern from responsible agencies about the recent rise in unsafe activities at the dam site.

   In recent years there have been a number of serious injuries and fatalities associated with this dangerous behavior at the dam. This also results in rescue operations that are dangerous for first responders and costly for local agencies. Human activities in the area of the dam also create environmental damage including illegal trails and discarded trash and waste.

^{Recreational divers at Rindge Dam pose a significant safety concern. Photos courtesy of Jeff Edwards, Otis College of Art and Design, Los Angeles (left).}