Recent storms in southern Santa Barbara County have delivered some of the highest rainfall rates in years. With the heavy rain, local debris basins refill with coarse gravels and rocks once again. When this occurs, we face an important decision about where that material should go. The answer is straightforward: It belongs on the coast, where, before the debris basin installations, it arrived naturally.
Santa Barbara’s beaches depend not just on wave energy but on the type of sediment they receive. Historically, major storm events delivered fresh, angular cobble from the mountains — material that interlocks, resists movement, and forms a natural and durable upper‑beach armor. But for over five decades, debris basins such as the Santa Monica Basin have trapped this younger sediment upstream, where it has been then trucked to upland disposal sites. What remains on the beach today is mostly older, rounded cobble that has been repeatedly tumbled by waves.
This distinction matters. Rounded cobble is the product of long-term abrasion; its smooth surfaces roll easily under storm surge and are quickly swept offshore or down‑coast. Unless we restore the steady supply of younger, angular material to replenish and stabilize the beach, the remaining rounded cobble becomes increasingly mobile and increasingly scarce. The shoreline is left with little more than sand to face winter storms — an erosion scenario we are now seeing play out year after year…