First Horizontal Levee to Become Operational
Volunteers plant native wetlands vegetation in the Oro Loma Horizontal Levee sea level rise barrier.
Measure AA Passage Could Aid Projects Bay-WideOn Thursday, May 12, prominent figures from throughout the Bay Area came together for a briefing about the first Horizontal Levee Coastal storm-surge barrier ever built. The event, hosted at the San Jose headquarters of the Santa Clara Valley Water District, brought together representatives of Congressman Eric Swalwell, Fremont Senator Bob Wieckowski, and Chair of the Santa Clara Valley Water District Barbara Keegan, among other elected officials.
The Oro Loma project is located on the San Lorenzo shoreline just south of the Oakland Airport. It is designed to test the concept of using restored natural marshes as a defense against sea level rise, as well as to clean pollutants from wastewater that is discharged from Alameda County’s East Bay collection network. A team of scientists and engineers from the Oro Loma Sanitary District presented project details at the briefing.
One of the most significant potential benefits of the Horizontal Levee concept is the restoration of vast tracts of tidal wetlands in San Francisco Bay. John Bourgeois, Executive Project Manager of the South Bay Salt Pond Restoration project, spoke to the audience about the potential to employ it as a restoration method along several miles of shoreline within that 15,000-acre project’s boundary—
“The series of wastewater treatment plants along the East Bay shoreline is a potential source of fresh water for marsh enhancement. We are looking specifically at the Union Sanitary treatment plant as a source of recycled fresh water to create brackish marshes that we know existed along the East Bay shoreline 200 years ago. That natural gradient of marsh types has since been eliminated from most parts of the Bay. Restoration of this type would increase biodiversity, as well as help the marshes' ability to keep pace with sea level rise. We are excited about the possibility of using this type of Horizontal Levee concept as a regional strategy as part of the South Bay Salt Pond Restoration Project.”
The Bay Institute published a study in 2013 describing the Horizontal Levee coastal storm surge barrier and analyzing its economic benefits. We calculated that it would be almost half the cost of traditional levees, while providing exactly the same level of flood protection. http://thebayinstitute.org/the-horizontal-levee
A major feature of the Oro Loma Horizontal Levee Project is an experiment to test the structure’s ability to remove nitrogen from wastewater. Nitrogen is a pollutant of increasing concern that can cause blooms of algae that harm fish and other Bay wildlife. The biggest source of nitrogen in San Francisco Bay is from treatment plants discharging wastewater collected from millions of homes and businesses.
Wetland plants remove nitrogen from wastewater naturally, essentially using it as fertilizer. The Oro Loma project is testing the efficacy of the Horizontal Levee barrier at cleansing the harmful pollutant from discharges of treatment plants. The innovative, gently-sloping levee at Oro Loma has been sown with native wetland plants that will absorb nitrogen through their roots, thereby removing it from water that would otherwise carry the pollutant into the Bay.
The Oro Loma project is the type of wetland restoration that Measure AA, on the June 7 ballot, is intended to promote throughout San Francisco Bay. In addition to the environmental benefits that are provided by restoring large tracts of the Bay’s original wetlands, these projects would help reduce flood damage resulting from rising sea level. The Bay Institute believes that Measure AA is a cost-effective way to accomplish these two urgent goals.
Stay tuned for more updates as the Oro Loma project progresses. Construction will soon be complete and the first rains of this fall will signal the beginning of operations at the site. And remember to vote on June 7.