Completed in 2017, the Oro Loma Horizontal Levee near Hayward, California was the first of its kind and informed the design of the Palo Alto project, and others. A sign explains the horizontal levee pilot project to visitors at the Baylands Nature Preserve. Charlotte BurksBy mimicking the natural world, the horizontal levee also provides the conditions native species need to thrive. By design, the horizontal levee will restore the vegetation and habitat that salties and other estuary wildlife rely on. The results could help justify the higher costs often associated with green infrastructure projects like the horizontal levee, explained Engelage.