Resource Protection Issues: Landslide Disposal

The Big Sur Coastline
Adjacent to the sanctuary, the Big Sur coastline along the central coast of California is characterized as a meeting of land and ocean that is unparalleled in natural beauty with high cliffs, rugged canyons and crashing surf. This is a unique stretch of coastline and wilderness valued as an international treasure and a special place for those who live there and all who visit the area. This is also a unique and special area in the sanctuary where the continental shelf hugs the coastline and several deep offshore canyons define a special component of the sanctuary marine ecosystem. An upwelling of deep, cold, nutrient-rich waters at Pt. Sur supports a blooming of phytoplankton, providing the foundation for marine life rich in marine invertebrates, kelp forests, rockfish, seabirds, sea otters, sea lions and migrating whales. Onshore, a relatively thin series of coastal watersheds drain the coastal terrain toward the ocean through steep canyons of open oak woodlands and towering redwood forests. This special region offers a unique opportunity for agency partnerships in protection and management.

Highway 1 along the Big Sur coastline was constructed through this geologically diverse landscape in the 1930's and opened in 1937. Parts of the highway north of Big Sur follow the Old Coast Road, completed from Monterey to Big Sur by Monterey County in the 1880's. Construction of the highway involved extensive excavations that utilized steam shovels and blasting. Fill was placed in minor canyons and bridges constructed across major canyons. The highway has a long history of landslides that have both landed on the highway and undermined the road bed. Road closures have been common, with long-term closure mainly due to large landslides in years of heavy rainfall.

Landslide management
In conducting landslide repair work on Highway 1 prior to the designation of the sanctuary, maintenance practices of the California Department of Transportation (Caltrans) 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 dispersion in marine systems. The disposal of landslide debris affects marine habitats and biological communities by direct burial, sand scour and plumes of fine suspended sediment. Sanctuary regulations prohibit the discharge of material within its boundaries, and secondly, prohibit the disposal of material outside the sanctuary boundaries that subsequently enters the sanctuary and harms resources.

The severity of winter storms in 1998 closed Highway 1 along the Big Sur coast for several months, and subsequent landslide and road repairs resulted in approximately 1 million cubic yards of excess material. The sanctuary's regulations prohibited direct disposal of material into the Sanctuary, but allowed the disposal of some material between the highway and mean high tide line at specific sites, with specific criteria such as compaction of fill and revegetation.

As a result of the storms of 1998, Cantrans moved forward on the development of a management plan for Highway 1 long the Big Sur coastline, from Carmel River in the north to San Carpoforo Creek in the south. This entire area is adjacent to sanctuary waters. The development of the Coast Highway Management Plan (CHMP) was led by Caltrans, in conjunction with other regulatory agencies including the sanctuary, and congressional and community representattives. As a result, Caltrans made a significant effort to identify land disposal sites as a proactive approach to deal with future landslides. However, the amount of cubic yards that these sites can accomodate is limited, and therefore Caltrans asked the sanctuary to consider ocean disposal in the future.

The sanctuary and the CHMP lacked a survey of marine resources along typical landslide areas and sites where Caltrans may seek to dispose of rock and soil debris onto the shoreline and into the ocean. Highway 1 management and repair strategies, even with objectives to minimize earthwork impacts and overall disturbances, continue to require sutiable locations for depositing excess material. The handling of materal at a landslide site or exporting to a suitable disposal site continues to raise concern about the potential for impacts to shoreline habitats. Evaluating shoreline habitats for sensitivity to these activities was an essential component to determining the effects of landslide material being depositied or redistributed on or near the shoreline. thus, the sanctuary conducted a survey of the marine resources and an evaluation of sensitive habitats to enable decision-makers to avoid disposal at critical, valuable areas and to identify areas with low resource value that may be suitable for ocean disposal of rock and soil by Caltrans. This marine resources survey and assessment has provided resource managers with over 100 spatial data sets as well as additional detailed data, an established method for continuing to collect and analyze data, improved response protocols, and a common understanding of the value of Big Sur's marine and terrestrial resources and the road which supports our communities and visitors.