Mountain View’s salt pond restoration project set to begin next year

A massive undertaking to restore wetlands along Mountain View’s coastline will finally begin construction in 2022, with plans to shore up levees and build out new trails to accommodate the return of the coastal marshlands.

City officials are working with state and regional agencies to support a decadeslong effort to convert more than 15,000 acres of salt ponds back to native habitat. The restoration project is the largest of its kind on the West Coast, and seeks to erase a legacy of industrial salt production by the global conglomerate Cargill.

Though restoration efforts began in 2008, the latest phase now seeks to restore marshlands next door to Mountain View, specifically ponds “A1” and “A2W” that sit just north of Shoreline Regional Park and Stevens Creek. Breaking down the barriers surrounding the ponds will allow for water to flow into both, bringing with it silt that will eventually allow marsh plants to establish, according to city staff.

The project not only brings back coastal habitats that have been destroyed going back to the 1850s, but it also safeguards against sea level rise. Between the open waters and the city’s shoreline will be a gradual slope of soil called a “habitat transition zone,” a buffer that will reduce flooding by mitigating the effects of waves hitting the coast.

The project also includes over a mile of new trails along the eastern edge of pond A2W, giving the public a chance to travel farther into San Francisco Bay to observe wildlife and habitats, according to city staff.

Breaching the levees is no easy task, however, and it does come with some side effects that the city needs to deal with. The higher water levels will result in tides encroaching on the city’s landfill levee, potentially causing erosion. City officials say a protective surface — likely a retaining wall of rocks or concrete blocks — will be needed to keep the levee from being damaged.

The restored tidal flows also threaten to flood a portion of the Bay Trail near Stevens Creek, and city officials say the trail will need to be elevated to avoid being inundated during the high tides.

Though the California State Coastal Conservancy finished its draft plan for the project in November, the city-side planning for erosion protection and trail improvements is still underway. The early estimates show Mountain View’s projects are going to cost about $3 million, though the state Coastal Conservancy is expected to share some of the costs. The city has already committed just shy of $5 million to the Salt Pond Restoration Project.

The Mountain View City Council voted last week to approve the city’s role in the restoration effort, which includes the design and construction of the trail and erosion protection along the landfill levee north of Shoreline Park.