What Is a Lagoon?

There is an ongoing scientific debate over how to precisely define a wetland.

One authoritative source often quoted, the state Coastal Act, defines wetlands as “lands within the coastal zone which may be covered periodically or permanently with shallow water.”

A lagoon is a type of wetland, as is an estuary. On the Southern California coast, both lagoons and estuaries are usually framed by a salt marsh. Among the habitats that can be distinguished at wetlands are: salt marsh, salt flats, eel grass beds, tidal creeks, intertidal sands and mud flats.

Lagoons come in many shapes, sizes, depths and varieties, ranging from fresh water to salt water to brackish, which means a combination of both. North County has all three varieties.

The origin of the lagoons dates back 25,000 years to the Ice Age, when melting glaciers caused the sea level to rise and flood coastal valleys. At one time many North County lagoons were deep embayments that probably extended eastward as far as El Camino Real.