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20 years after restoration this marsh is a birder’s paradise

The San Joaquin Marsh has attracted more than 280 bird species since Irvine Company launched plans to restore Orange County’s largest coastal freshwater wetlands

IRVINE, Calif. (April 14, 2016) — Word recently spread among birders in Orange County of a rare sighting: a long-eared owl was roosting in Irvine.

It perched on a pine bough in a pristine oasis.

Nearby, tree swallows darted over bulrushes; blue-winged teal grazed in preparation for their flight to Alaska; and an osprey circled a series of ponds searching for carp.

A quarter-century ago, this was degraded marshland overrun by black mustard, cocklebur and artichoke thistle.

Now, thanks to restoration by Irvine Company and the Irvine Ranch Water District (IRWD), it encompasses 300 acres of coastal freshwater wetlands known as the San Joaquin Marsh and Wildlife Sanctuary.

The sanctuary is home to about 38,000 native trees, 24,000 native shrubs and more than 280 species of birds, including the endangered least Bell’s vireo, a chatty little thing (barely 5 inches long) that flies 2,000 miles north each spring just to summer here.

The wetland is a major stopping point for migratory birds. And each year it is a stopping point for about 40,000 people who seek respite in a thriving county of 3 million. Here, they can meander along 69 acres of ponds, sit and listen to songbirds, or hike 10 miles of trails through willow, sycamore and natural woodlands that provide solitude from city life.

“Thanks to a truly collaborative effort … the San Joaquin Marsh is once again a vital habitat for fish and birds,” former Secretary of the California Resources Agency Mary Nichols said in 2000 after the restoration. “These restoration activities are a wonderful example of how we really can reclaim California’s natural heritage.”

Today, 20 years after restoration began, the San Joaquin Marsh stands out as one of the most successful wetland-restorations in the nation. And it works as hard below the surface as above. For down there, in the mud, is where it purifies more than 6 million gallons of water a day flowing into Newport Bay.


The San Joaquin Marsh lies along the banks of the San Diego Creek, which descends 16 miles from the foothills of the Santa Ana Mountains into Upper Newport Bay.

As part of the original 93,000-acre Irvine Ranch, this parcel adjacent to UC Irvine stood as open floodplain for many years. By the early 1900s, it housed several hunt clubs that built small ponds to attract ducks. In the 1950s, it became farmland for lima beans, peppers and tomatoes.

When the last duck club closed in 1988, the old ponds dried up, and the surrounding fields went to seed, overrun by non-native vegetation.

A decade later, Irvine Company dedicated $12 million to restore the marsh, whose entrance is off of Campus Drive near University Drive. The company donated most of the land to the IRWD and formed a public-private partnership that was lauded as something to be emulated throughout the state.

The partnership included the IRWD, the City of Irvine, environmental groups and regulatory agencies, including the U.S. Fish and Wildlife Service. Together, they created more than a wildlife sanctuary. They created a natural filtering system to clean the San Diego Creek of nitrogen that came from urban runoff.

To do this, the IRWD built six large ponds, irregularly shaped with peninsulas and inlets like those in the wild. Some are deep-water to attract diving birds; others are shallow for wading birds; three feature islands for ground-nesting birds.

Each was surrounded by bulrushes and winding paths to provide visitors with a sense of solitude. At first glance, the bulrushes appear to serve merely as scenery. But they are instrumental in scrubbing clean the 6.5 million gallons of water diverted daily from the San Diego Creek.

“While IRWD continues to expand the number of natural treatment system sites throughout the region, the San Joaquin Marsh remains the most visible and successful example of how a natural environment can be used to treat urban runoff in order protect and improve local environmentally sensitive areas,” said Ian Swift, natural resources manager for IRWD.

It takes 20 days for this water to flow from pond to pond. As it does, bacteria in the bulrush roots and mud metabolize and remove nitrates that, left untreated, would trigger algae blooms harming marine life in the Upper Newport Bay Nature Preserve and Ecological Reserve about one mile away.

This natural filter eliminates 75 percent of the nitrogen (about 35,000 pounds a year) and 75 percent of the phosphorous (about 500 pounds a year) before the water empties back into the creek.

Today the IRWD maintains the 300-acre wetlands along with 23 other natural treatment systems it has created throughout the county to naturally clean urban runoff. As a result, Upper Newport Bay hasn’t seen a large-scale algae bloom in over a decade.

“This is an example of environmental planning that should be in textbooks for generations to come,” says Tom Mulroy, principal ecologist at Leidos, in Carpinteria, and former consultant to the project.

Since restoring the marsh, wetlands biologists have counted 121 species of plants and 282 species of birds. In 2014, they saw a phenomenon that hadn’t been witnessed in coastal Orange County for 110 years: They saw a yellow warbler nesting – right here in San Joaquin Marsh.


California has lost more than 95 percent of its coastal wetlands in the last century.

The San Joaquin Marsh remains a shining example of wetlands preservation, a hidden gem two-thirds the size of New York City’s Central Park, in the heart of Orange County.

“You can be here and feel like no one else is around,” says Trude Hurd, project director of education for the Sea & Sage Audubon Society, who has worked at the wetlands since 1992. “It’s like your own private wilderness area.”

As she walks, she points out tree swallows newly arrived from Mexico; Canada geese preparing to fly north; and the resident osprey adding twigs to its nest, which now holds eggs.

Twice, Trude and a friend have won first place in a national bird-watching competition for having seen the most bird species in a single day from a single location.

“Sea & Sage Audubon wants to protect birds,” she says. “And Irvine Company has done a good job of protecting this area for birds.”

With that, she joins a group of birders staring intently into a small grove of pine trees. Deep inside, on a bough near the trunk, sleeps a long-eared owl, a sight she’s seen only once in Orange County.

What makes this restored marsh special?

“That,” she says.

She is pointing at a rarely seen owl. But she could be pointing in any direction in this oasis, and still feel the same.