Habitat Alteration

Southern California represents one of the most dense urban settings in the nation, and estuarine habitats and adjacent lands have been heavily modified by human activities.  The situation for habitats associated with the Tijuana River Reserve are particularly acute, as the Reserve occupies a portion of land on the International Border with Mexico.

Hydrological and biological inventories and assessments were conducted and a Geographic Information System database was developed as a foundation for restoration planning. A long-range plan for restoring the estuary’s tidal prism and intertidal wetlands was developed, and the plan was reviewed in a programmatic EIR/EIS approved and adopted by the Fish and Wildlife Service and the Coastal Conservancy.

The original Tijuana Estuary Tidal Restoration Program (TETRP) called for approximately 500 acres of intertidal wetland restoration to be undertaken in increments using an adaptive management design process with monitoring and evaluation of projects to influence design decisions for subsequent phases. The first project of the program, a 1,200-foot channel connecting the northern end of Oneonta Slough and the tidal ponds southeast of the visitor center, was constructed in winter 1997.  Subsequently, final engineering plans for a 20-acre intertidal wetland restoration were prepared as a first module of the 500-acre south arm component of the TETRP.  This 20-acre Friendship Marsh (Model Marsh), which emphasizes tidal creeks and the marsh plain, was constructed in 2000-2001.  Excavated materials were used on-site to restore a degraded piece of upland habitat that was once a sand-mining operation.  Monitoring for regulatory compliance and research purposes is ongoing.

Since completing the Model Marsh, project leaders and hired consultants have adjusted the acreage of land to be included in the restoration program to approximately 200-250, largely due to sedimentation risks and/or degradation in the most southerly areas of the original 500 acres.  Through a project facilitated by the Southwest Wetlands Interpretive Association and funded by the State Coastal Conservancy, a feasibility report was completed for a 250-acre restoration project in the south end of the Reserve. The Stewardship Program plays a role in large projects such as these by engaging in the planning and implementation process and through assistance with regulatory agency communications and environmental review.

This area also faces disturbance pressures associated with border infrastructure and security and undocumented immigration activity. A new Border Infrastructure Project has been a major focus of the U.S. Department of Homeland Security. Elements of this project for the local region have been under construction for years. In the summer of 2008, following the transfer of nearly 50 acres of land from the Reserve to U.S. Department of Homeland Security, major construction for the Border Infrastructure Project was initiated in this region.

A significant focus of this project is to develop a fortified barrier and patrol road system that stops illegal crossings and allows for rapid Border Patrol Agent response along the length of the International Border. Adjacent to the Reserve and in closely associated regions, project construction has resulted in the movement of major volumes of earth, cutting mesa tops and filling canyons in an effort to level the topography of the area and facilitate a linear road and fence corridor. The Stewardship Program works to conserve natural resources threatened by this condition. Some of the regular activities include: work with Border Patrol agents to communicate our resource objectives and develop an understanding of U.S. Homeland Security needs; attempt to minimize disturbance and effects from patrol infrastructure impacts; and monitor conditions.