Landslides

The Big Sur coastline along the central coast of California is unparalleled in natural beauty, an incredible mix of high cliffs, rugged canyons, and crashing surf. This stretch of coastal wilderness is an international treasure and a special place for residents and visitors alike. Big Sur is also a unique and special area in the sanctuary, where the continental shelf is narrow and hugs the coastline, with several deep, submarine canyons close to shore. Deep, cold, nutrient-rich waters are upwelled at Point Sur, supporting plankton blooms and providing the foundation for a rich diversity of marine life, including algae, invertebrates, kelp forests, rockfishes, seabirds, sea otters, sea lions, and migrating marine mammals. Onshore, a relatively thin series of coastal watersheds drain the coastal terrain, connecting land and sea through steep canyons of oak woodlands or towering redwoods.

Prior to the designation of Monterey Bay National Marine Sanctuary, California Department of Transportation maintenance practices during landslide repair work on Highway 1 often involved moving landslide and road repair debris into the adjacent marine environment. Maintenance and catastrophic road repair activities often deviated considerably from the natural patterns of slide movement and sediment transport in marine systems. The disposal of landslide debris affects marine habitats and biological communities by direct burial, sediment scour, and turbidity plumes of fine suspended sediment.

The storms of 1998 led to the development of the Coast Highway Management Plan in which the California Department of Transportation now makes a significant effort to identify land disposal sites as a proactive approach to deal with side-casting of the land-slide materials (e.g., soil, rocks, vegetation placed downslope of the highway) and requires a permit from Monterey Bay National Marine Sanctuary. Studies were conducted in order to better understand the sensitivity of the shoreline habitats to existing disposal practices, and effectively minimize the negative effects of landslide material deposition or redistribution on or near the shoreline. The Marine Resources Survey in Big Sur, and subsequently the Big Sur Nearshore Characterization, were among the first comprehensive studies to accurately characterize selected intertidal and subtidal communities of fishes, invertebrates, and algae that are potentially impacted by natural landslides and subsequent disposal management practices. Many of the results have been aggregated by sanctuary staff in a geographic information system (GIS) database initiated by the Coast Highway Management Plan. The resulting GIS project contains over 100 spatial data sets including shoreline types, aerial photos, geological data, and Highway 1 postmiles. Sanctuary staff use this database to inform permitting processes and update it as new information becomes available (e.g., added abalone critical habitat data).