If current predictions hold, the entire Palo Alto Baylands could be submerged by the middle of the century because of sea level rise, a destructive predicament that would threaten both the sensitive habitat and the critical infrastructure in the nature preserve.
To prepare for rising tides, the city is moving ahead with the creation of a new Sea Level Adaptation Plan, a document that will consider upgrades to vulnerable infrastructure, a risk assessment of all structures near flood-prone areas and strategies that new developments would have to adopt as they adapt to a wetter reality. It is also pushing forward with plans on a levee project that would use treated wastewater from the nearby treatment plant to support a newly created nature habitat in the transition zone between the tidal area and the terrestrial uplands area.
Palo Alto officials plan to provide an update on both efforts this Wednesday, Sept. 9, when the city hosts a webinar on sea level rise. The event will go from 3 to 4 p.m. and will include staff presentations from the city and Santa Clara Valley Water District, which will discuss the agency's own long-term planning efforts around sea level rise.
According to Palo Alto's recently adopted sea level policy, the city also intends to undertake new partnerships with surrounding cities, including East Palo Alto and Mountain View, for joint planning efforts and projects such as levees to address the rising tides.
Palo Alto has already partnered with the San Francisco Estuary Partnership to create a concept plan for a "horizontal levee," a structure that aims to both boost the city's flood protection and protect habitat that would be threatened by sea level rise. Unlike traditional levees, which tend to be steeper and composed of rocks (known as rip rap), the proposed levee would be a gentle berm with "green" infrastructure that can support a brackish marsh in the transition zone close to the Palo Alto Airport and Baylands Golf Links golf course.
Samantha Engelage, senior engineer in the city's Public Works Department, said the current flood-control levees near the Baylands don't meet standards set by the Federal Emergency Management Agency and at times experience overtopping, particularly when king tides coincide with storm events. In a February update to the city's Parks and Recreation Commission, Engelage said the levees need improvement "to secure Palo Alto and the key infrastructure that is in the Baylands," including the airport, the golf course and the Regional Water Quality Control Plant.
The project has already received two grants, from the Environmental Protection Agency and California State Coastal Conservancy, which funded the planning effort. Engelage noted that throughout the Bay Area, transition zones between marshlands and upland areas have been "decimated" by development. As such, regional agencies have made these transitional areas "a high restoration priority."
"The regional perspective is, 'How can we now take advantage of all this money and effort to address flood control, while also addressing this type of ecosystem that has been decimated throughout the area,'" Engelage told the commission at the Feb. 25 meeting.
As part of Palo Alto's recently adopted plan for sea level rise, the city will be conducting a "vulnerability assessment" that will identify critical infrastructure that could be at risk and estimate the economic impact of vulnerability for both public and private properties. The city also plans to create a multiyear implementation plan that could include zone changes near the Baylands, new permitting requirements for projects in at-risk areas and triggers for relocating facilities away from the area, according to Palo Alto's policy on sea level rise.
The policy, which the city adopted in March 2019, notes that if the Palo Alto Baylands is submerged by mid-century, as predicted, they would lose their ability to serve as buffers during flood events, to attenuate storm surge or to sequester carbon. Sea level rise would also have a disruptive and potentially devastating impact on local habitats, as well as on the recreational offerings throughout the preserve.
"The encroachment of Bay water may alter or eliminate habitat for endanger species that reside in Palo Alto Baylands and the millions of birds that use the Palo Alto segment of the Pacific Flyway for seasonal migration," the policy states. "The recreational and inspirational services of the Palo Alto shoreline could change if Baylands trails, playing fields, and golf course are surrendered to encroachment of San Francisco Bay."
To register for the Wednesday webinar, visit eventbrite.com.