San Diego Bay is the largest estuary in San Diego County and has been extensively developed as a port.  It covers 10,532 acres of water and 4,419 acres of tidelands.  Only 17 to 18% of the original Bay floor remains undisturbed by dredge or fill.  Ninety percent of the original salt marshes and fifty percent of the original mudflats have been filled or dredged for development.   Extensive development on the San Diego Bay waterfront has created the need to protect the natural resources that are found within this rare water body.  In particular the protection of eelgrass as well as endangered species is especially important.  Endangered species found in the vicinity of San Diego Bay are:   the California Least Tern, Light-footed Clapper Rail, Brown Pelican, Peregrine Falcon, Western Snowy Plover, Beldings Savannah Sparrow, Green Sea Turtle and the Salt Marsh Bird's Beak. 

Eelgrass

Eelgrass is vital to aquatic ecosystems, and must be protected in San Diego Bay.  Eelgrass habitats harbor a diverse assemblage of invertebrate and vertebrate fauna, and are considered essential fish habitat because they form valuable nursery areas for a variety of ecologically and commercially important species.  Eelgrass degradation and loss has increased worldwide, chiefly in response to increases in coastal development, boating, and fishing in shallow near shore waters.  To manage these increasing impacts, policies requiring mitigation for loss of eelgrass through in-kind and out-of-kind restoration of eelgrass habitat have been mandated.

California Least Tern

The California Least Tern was once considered abundant, but has suffered dramatic declines due to human encroachment and destruction of its nesting habitat.  Formerly the terns regularly nested on sandy beaches and mudflats near the ocean, but human disturbance related to dredging and development projects have drastically reduced nesting habitat.  The construction of the Pacific Coast Highway in the early 20th century destroyed nesting beaches as well as making these areas more accessible to human encroachment. Today, the construction of housing developments continues to reduce suitable breeding grounds, and many remaining tern populations choose to nest on mudflats away from the
ocean and man-made landfill instead.  These more terrestrial sites have made the nesting terns and their chicks increasingly vulnerable to dogs, cats and raccoons.  The tern's fishing grounds have also been severely impacted by dredging, development and pollution. 

Many artificial nesting habitats have been developed to help mitigate the habitat loss, particularly around San Diego Bay.  There are currently seven nesting sites around the bay: three on land that belongs to the military, three on land governed by the San Diego Unified Port District, and one that is on a US Fish and Wildlife (USFW) preserve.
 

Green Sea Turtle

The East Pacific green sea turtle (Chelonian mydas) is an endangered species and resident of the San Diego Bay.  It is estimated that the resident population in approximately 30 to 60 sea turtles.  The turtles migrate from their nesting beaches in Mexico, to the warm and shallow water of South Bay near  the discharge channel of the South Bay power plant.  South Bay provides a safe habitat where the turtles can forage in the eelgrass beds.  One of the main factors that has caused the sharp decline in the sea turtle population has been poaching and illegal harvesting.  San Diego Bay provides one of the few protected habitats where the turtles do not face these threats.  It is also a prime study area for researchers.
Currently, efforts to restore the green sea turtle population focus on public education and tracking the migratory patterns of the turtle.  There has been a strong focus on public education in Mexico where traditionally, turtles have been harvested for food and other consumer items.  Other factors such as boat collisions and entanglement in trash and fishing line have also been identified as threats to the turtle populations.

San Diego Bay Natural Resource Management Plan

An extensive management plan has been established to protect the natural resources of San Diego Bay.  This plan can provide you with further information on the extensive efforts surrounding the protection of San Diego Bay's natural resources.