Many ask, "What is an estuary?" The simplest answer is, "A place where fresh water and salt water meet." The tidal mouth of any river is an estuary. Local residents are lucky to have in their midst the largest remaining natural estuary in Southern California, the Back Bay, which stretches from Pacific Coast Highway to Jamboree Road near the Corona del Mar (73) Freeway. Many people come to enjoy the beautiful scenery, but few realize its ecological importance and the threats posed to it by human activities in the watershed.
The Back Bay is an important rest stop and/or winter home for birds migrating from Canada and Alaska, and a nesting area for summer migrants and year-round residents. The bay is also a spawning ground and nursery for many commercial and sports fish, including halibut and bass. The Back Bay, or Upper Bay, additionally plays a huge part in protecting the recreational boating infrastructure of the Lower Bay and the beaches of Newport Beach.