The Newport Bay/San Diego Creek Watershed has undergone many changes since the first Spanish settlers arrived, but none more obvious than the impacts related to decades of urban growth. Since the end of World War 11, commercial and residential development has replaced open space and agricultural lands. By the late 1960's, development had significantly altered the landscape, increasing the size and number of channels that drained into Newport Bay. The impacts of construction and the new storm flow drainage systems were not widely recognized until the storms of 1969 deposited tremendous volumes of sediment in Newport Bay. Business joined government in seeking potential solutions to the newly evident problems of sediment scour and deposition. Basins were constructed in foothills, channels, and the bay to control sedimentation.

The urbanization of the watershed continues today, with more growth planned for the forseeable future. Once stable channels have significantly eroded. More severe winter storm seasons, such as the El Niño winter of 1997-98, have tested the stability of the channels in the watershed. In that year alone, several hundred thousand cubic yards of material deposited in the bay and watershed channel basins were filled to capacity. Channel erosion, including incising and loss of bank slopes, were clearly evident along Serrano Creek another tributaries to the bay.

For years, there have also been concerns about the declining water quality in the watershed and bay. Regulatory agencies such as the Environmental Protection Agency (EPA), the Corps, and the California Regional Water Quality Control Board (RWQCB) are more actively enforcing water quality standards in the watershed and bay. EPA and the RWQCB have implemented phased Total Maximum Daily Loads (TMDL's) for the watershed and bay. Local governments are finding it more difficult and expensive to try to independently comply with multiple-agency water quality requirements. Private property owners and cities are also adversely affected by upstream and downstream construction. Large developments have increased surface runoff, and improved channels carry storm flows at much higher velocities, resulting in greater downstream channel scour and erosion. Habitats for many species are also disappearing and remaining habitats are being isolated because new construction has cut off long-used wildlife corridors. Many times residents are not aware of new projects until too late, because developers and regulatory agencies do not effectively notify the public.

The public has become increasingly vocal about the dwindling natural resources in the Newport Bay/San Diego Creek Watershed, and they want a say in future watershed issues before it is too late. Progress has been made in the preservation of open space for sensitive species or habitats. Committees, organizations and small groups have been formed to address multiple watershed and bay problems. Hundreds of studies have been completed since the 1960's to address a variety of problems in the watershed and bay. The projects constructed according to some of these study recommendations have had varying degrees of success because urban growth has continued so rapidly.

The Corps has been actively involved in a two-phased, cost-shared study effort at Newport Bay since the early 1990's. The current ecosystem restoration feasibility study is nearing completion, and will address restoration measures for the Upper Bay. In 1998, the Corps was requested to prepare a reconnaissance report for the Newport Bay/San Diego Creek watershed. This Project Study Plan (PSP) is a product of that study, and is the plan of action for a more detailed, cost-shared feasibility study. The Corps will work with the study sponsor, Orange County Public Facilities and Resources Department (OCPFRD), in preparing products that compliment ongoing watershed study efforts. The purpose of the watershed feasibility study will be to develop an integrated "watershed management plan" (the PLAN) to maintain, restore and enhance activities that contribute to a healthy watershed and bay. The Corps will work with the Newport Bay Watershed Executive Committee (NBWEC) and Management Committee (NBWMC) to coordinate study activities. Both committees are represented by resource managers, regulators, political entities, developers, and the public. The NBWMC will be used as the "umbrella" organization for this study and other watershed affairs to provide open communication and coordination for all members and to avoid duplication of efforts. The PSP is a living document and will be revised based on changed conditions and results of other study efforts.

The Corps will provide comprehensive tools to assist managers in making decisions that affect the future of the watershed and bay. It is intended that these tools benefit the decision-makers long after the completion of the study. Models will be developed to address hydrologic, hydraulic and sediment transport functions in the watershed. These models will be linked to Orange County's Geographic Information System (GIS) so that they can be used to look at different restoration measures, or at impacts resulting from proposed future land use changes. Several preliminary sites have been selected to investigate the potential for site specific restoration projects. These "spin-off" studies will be investigated at a reconnaissance level for this study. If there is strong interest in pursuing any of these measures, and a willing cost-sharing partner is identified, a separate site-specific PSP will be developed and implemented. Current channel and basin maintenance activities will be reviewed to recommend potential improvements in current activities, from a comprehensive watershed approach, to optimize trapping and erosion control activities near the source of the problems.

Environmental surveys will be conducted to map remaining riparian habitats along stream corridors and to support restoration measures. A comprehensive, joint programmatic Environmental Impact Statement/Environmental Impact Report (EIS/EIR) will be developed to provide information for use in deciding on future restoration or development activities. The models being developed will indirectly assist in addressing some of the TMDL objectives by identifying how effective the current sediment control facilities are, and what may happen in the future if new structural or non-structural facilities are constructed, or if maintenance activities are modified. Spin-off studies, such as constructed wetlands, will also address potential benefits that will assist in meeting the TMDL objectives. Information on surface water quality and ground water quality, and the interaction of surface water and groundwater will be investigated for this study.

The study area includes the entire watershed and bay, but study efforts will focus on the watershed since the Corps' Newport Bay feasibility study is nearing completion. Recommendations and analyses in this watershed study will address any impacts to sediment transport, water quality, or operations and maintenance activities within the bay. This cost-shared study is estimated to take 29 months to complete at a total cost of $2,340,500. Some of the costs will be offset by the contribution of in-kind services from Orange County.