Community Commentary:

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. Here, fertile soil washed down from the watershed is deposited, creating mudflat that is soon teeming with worms, clams and other invertebrates.

Cord grass sprouts in the higher, shallower areas, creating saltmarsh habitat. Constant mixing and flushing of the water through the action of the tide, shallow sheltered water that sunlight easily penetrates, and plenty of nutrients all contribute to the abundance of plankton and algae that form an important part of the food web for fish, birds and other wildlife.

Newport Beach residents are lucky to have in their midst the largest remaining natural estuary in Southern California.

The Back Bay, stretching from Pacific Coast Highway to Jamboree Road near the 73 Freeway, includes the Upper Newport Bay Ecological Reserve, which is home to nearly 200 species of bird and about 80 species of fish at one time of the year or another. Many people come to enjoy its beautiful scenery.

But few realize the ecological importance of it and other natural estuaries, and the threats posed to it by human activities in the watershed.

At the southern end of the Ecological Reserve sits the Back Bay Science Center — a 13,000-square-foot facility built through a partnership of the California Department of Fish and Game, the city of Newport Beach, the Orange County Health Care Agency and UCI.

The mission of the Back Bay Science Center is to provide a hands-on facility where students and the public can study and enjoy the estuarine ecology of Newport Bay and the marine ecology of the ocean; and to promote natural resource conservation and stewardship throughout the watershed. The facility includes the water quality lab responsible for bacterial analysis of water samples collected at the local beaches, and a teaching lab equipped for research-based science education for Grades seven through college.

Here junior and high school students will be able to work side-by-side with some of the region’s top scientists.

The Back Bay Science Center is normally only open to participants in school, scout and other organized programs. However, on Saturday it will be open to the public for its Estuary Awareness Day celebration.

This is a great opportunity to visit the teaching lab, observe plankton and other cool things under a microscope, see sharks, rays and other fish found in the bay and touch sea stars and other marine animals.

There will also be pontoon boat tours of the Back Bay. Educators from the various organizations that partner with the Department of Fish and Game will have exhibits set up to explain how estuaries function and how you can do your part at home to protect and preserve them.

The event runs from 10 a.m. to 4 p.m. There will be free parking, admission and activities. Refreshments will be available. For directions and more information, go to www.newportbay.org.

ROGER MALLETT is executive director of Newport Bay Naturalists & Friends