The successful enhancement and restoration of coastal lagoons requires a comprehensive understanding of the physical and biological conditions in each lagoon and the processes that influence the lagoon's performance. Since lagoons differ substantially from one location to another, the problems that affect lagoon performance differ as well. Coastal lagoons in Southern California (Figure 1) tend to be small with surface areas of a few hundred hectares or less and mean water depths of less than 2m. Careful monitoring studies of lagoons, together with historical reviews and data from previous studies, enable wetland scientists to recommend successful, cost-effective, environmentally sound plans for enhancement and restoration of Southern California lagoons.

Recent understanding of the settings and physical processes controlling lagoon performance will enable us to produce improved schemes to enhance these systems. Usually the biological performance of a wetland depends on improvement of the physical parameters, such as tidal flushing, water quality, freshwater flow reduction, and channel and basin sedimentation. Other factors that should be taken into consideration are the impacts of the wetland on adjacent beaches, the response of the wetland to dry and wet periods, any possible or expected future climate changes, and biodiversity management.

This paper discusses cases of environmental impacts on selected Southern California lagoons, together with proposed or existing projects to reduce or mitigate these impacts.