Palo Alto’s 500-foot horizontal levee reuses wastewater to restore marshes and test sea-rise defence

Palo Alto’s 500-foot living levee reuses treated wastewater to restore marsh habitat and fight seas (Image Credit: City of Palo Alto) A shoreline defence can be more than a wall. In Palo Alto, California, engineers have built a broad, gently sloping landscape designed to protect the coast while functioning like a living ecosystem. The project sits along Harbor Marsh in the Palo Alto Baylands and combines native vegetation, treated wastewater and a nature-based approach to sea-level rise. Unlike a conventional concrete or steep-sided levee, the new structure is designed to provide habitat as well as help reduce the effects of waves and rising water.According to the City of Palo Alto, the completed project is a 500-foot-long horizontal levee and the first of its kind on the San Francisco Bay shoreline to use treated wastewater from the city's Regional Water Quality Control Plant to irrigate native plantings. The project was completed in September 2026 after construction began in 2025.What is a horizontal levee?A traditional levee typically creates a relatively steep barrier between a community and the water. A horizontal levee takes a different approach. Instead of relying primarily ...