By Ted Trautman, Bay Nature
“Everything we’re doing here is illegal, infeasible, and unfundable,” Jeremy Lowe tells me with a rakish grin, as we watch a couple dozen volunteers, including several small children in galoshes, planting grasses in the mud. They’re working on an experimental levee near the bay’s edge in San Lorenzo, just west of Hayward, innocently enough. Lowe soon confesses that he and his colleagues aren’t outlaws after all. But this prototype levee, situated a half-mile from the bay, is so innovative that building it on the shoreline is prohibited, even though it could help mitigate a looming environmental crisis: the rising sea levels brought on by global climate change.
Most levees are basically just walls separating water and land. (Indeed, the word levee comes from the French verb lever, “to raise.”) In contrast, we’re standing on a relatively rare horizontal levee, very wide and almost flat, dropping just 5 feet in elevation as one walks its 150-foot width. This small prototype stretches 700 feet along the “shoreline” (in this case, a trench), while a grown-up one might span as much as 14 miles. Lowe, a geomorphologist at the San Francisco Estuary Institute and one of the project’s chief architects, compares it to a layer cake: Underneath the loam we’re standing on is a layer of sand and wood chips where microbes break down nitrogen-containing waste, and beneath that a stratum of dense clay and a hardpan that keeps the water used in this experiment from seeping into the bay. But since this layer cake sits on land owned by the Oro Loma Sanitary District, next door to its wastewater treatment plant and downwind of its aromas, I wish we’d talk about something other than food.
Read the complete story at Bay Nature. To learn more about the issue of rising seas, read the San Francisco Public Press special report on sea level rise.
