The coastal wetlands of Southern California form a thin rim along the steep coastal mountain and geologically active zones of North America. The geomorphology of these wetlands are affected by the rise of sealevel following the last ice age. Some twenty thousand years age, the sea level was about 130 m below the present shoreline. Over thousand of years, many deep canyons and wide valleys were carved by numerous creeks and rivers. Following the ice age and the rise of sea levels, most of the drowned valleys and canyons became bays or lagoons. The piling up of sands and sediments from creeks created a vast area of beaches, mud flats and marshes. However, with increasing population, less than 10% of the historic wetlands from Mexican border northward to Southern California remain. Over the past century, considerable alteration has occurred and greatly changed the local landscape.

Initially the land is cleared for agriculture. Frequently, farm lands and orchards leave the soil unprotected. Wetland deterioration were accelerated by the poor drainage and artificial fertilization. These cause eutrophication and filling of stream channels in the lower wetlands. In recent years the extensive housing development and harbor construction completely alter the dynamic nature of the wetland system. The most dramatic change is the construction of coastal highways and railways. Many roads run through the entrance of the wetlands and restrict the tidal exchange. Eventually the equilibrium between land and sea of the wetland is upset. The change in the environment has caused alarm to the local residents. Many projects trying to restore the wetlands have gained momentum and generated support from communities.

In the present study of the geomorphology of the coastal wetlands of Southern California, we would provide some current examples and case history of several wetland restoration projects. The cost and the benefit of these projects were evaluated. Their feasibility and applicability to the developing