California Department of Fish and Wildlife is responsible for the management of over 1.1 million acres of fish and wildlife habitat spanning over 700 properties statewide.  These properties provide habitat for a rich diversity of fish, wildlife, and plant species and comprise habitats from every major ecosystem in the state.  One of these properties is Upper Newport Bay which is an Ecological Reserve.  The purpose of Ecological Reserves are to conserve threatened or endangered plants and/or animals, and/or specialized habitat types, provide opportunities for the public to observe native plants and wildlife, and provide opportunities for environmental research.  Upper Newport Bay Ecological Reserve is a 752-acre property consisting of salt marsh, mudflat, and marine habitat.  Large mudflats with suitable loafing areas above high tide are extremely desirable for migrating shorebirds and waterfowl.  Sheltered waters provide foraging, spawning, and nursery habitat for marine fishes.

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Upper Newport Bay is a type of Marine Protected Area (MPA) known as a State Marine Conservation Area.  One of the goals for Upper Newport Bay State Marine Conservation Area is to protect the largest remaining estuary in Southern California.  The conservation area contains a mix of marshland and tidal flat habitats.  A variety of marine fish species may be found in the estuary, including California halibut, spotted bay bass, and croaker, whose young use it as a nursery area.  Invertebrates such as medusa worms and jackknife clams bury themselves in the mud, where they filter plankton from the silty water.  Because of its large size and location, close to 30,000 birds at a time may use the conservation area during winter migration.  The estuary also provides critical habitat and refuge for endangered bird species such as the California least tern.

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The California Department of Fish and Wildlife contains detailed information about Upper Newport Bay Ecological Reserve and Upper Newport Bay State Marine Conservation Area.