Going Big: Building an experimental habitat for a better Bay

Horizontal Levee
A “Horizontal Levee” is under development at Oro Loma. Rendering courtesy The Bay Institute.

This spring, Save The Bay’s Habitat Restoration team laid the groundwork of an enormous and unprecedented effort to create new habitat at a sewage treatment plant in San Lorenzo.

The 10-acre project at the Oro Loma wastewater treatment plant will eventually include a manmade wetland basin and a new type of levee. It’s all part of a giant experiment to mimic historic wetlands and address three crises that loom over San Francisco Bay’s shorelines: declining water quality, threats to wildlife habitat on the Bay, and destructive flooding caused by rising seas and increasingly powerful storm surges.

Braving long days in the hot sun at the treatment plant, our native plant specialists have already constructed the site’s giant outdoor nursery. With help from an army of our amazing corporate and community volunteers, we have already begun to propagate the 70,000 native seedlings needed to establish this new ecosystem. The site will double as an outdoor laboratory for researchers who will conduct field tests to better understand how treated wastewater and this new kind of levee can address critical issues facing the Bay.

We’re proud to be part of a diverse partnership on this complex undertaking, which includes The Bay Institute, San Francisco Estuary Partnership, the Oro Loma and Castro Valley sanitary districts, and others.

The Oro Loma Horizontal Levee project creates a new model for harnessing natural processes to protect shoreline infrastructure from three major problems:

Flooding due to climate change

Shoreline communities and infrastructure are threatened by hazardous storms, which will be worsened in coming years as storms become more hazardous and more frequent as sea level continues to rises. The Oro Loma project offers one solution in the concept of a Horizontal Levee.” Unlike the earthen sea walls of a traditional levee, the horizontal levee has a wide, gentle slope that mimics a historic wetland habitat. As in nature, this man-made tidal wetland will trap and redistribute eroded sediment, bulking up with plant matter and biomass, which can dramatically slow down and decrease the force of rushing water. Healthy wetlands can also counteract storm surges by acting as a natural sponge, each acre holding hundreds of thousands of gallons of water that can threaten shoreline communities.

Water quality

Plants chosen for this project can remove nutrient pollution from treated wastewater, yielding water pure enough to connect with outlying marshes and the Bay. That would help reduce serious water quality problems such as harmful algae blooms, which steal oxygen from the water, suffocate fish, and cause toxic effects in fish, invertebrates, and mammals, including humans.

Wildlife habitat

Our region’s severe drought poses a crisis for wildlife habitat as well as for humans, and competing needs for fresh water put even more pressure on Bay ecosystems. If successful, the Oro Loma experiment will suggest that treated wastewater can be a reliable source of fresh water for habitat areas in an era of increasing water scarcity.

With so many benefits, the potential for this experiment is incredible. Today, the Bay Area has 570 miles of levees and 22 wastewater treatment plants. Even if only 25 percent of these areas prove to be suitable sites for horizontal-levees, the horizontal-levee approach could provide flood control and new habitat on up to 5,000 acres of San Francisco Bay shoreline. That could mean a whole new approach to saving the Bay.

Establishing 70,000 native plants is no small undertaking. If you want to help us make this project a success, please email Rachelle Cardona to join our volunteer waiting list.