Turning Muck Into Marsh

What a sorry piece of earth is this patch of malodorous muck inside Mugu Lagoon near Oxnard. Beyond tender loving care, these 37 barren acres are in need of a total make-over.

A half century’s worth of sewage sludge dumped by the Navy festers in three big storage ponds. It is contaminated with heavy metals. Stench, like a stinky wet blanket, hangs in the air.

But scientists from UCLA and the Point Mugu naval base see an opportunity to help nature restore the site. They think it is the perfect spot to build a marsh for migratory birds and other wetland wildlife.

“When I first saw it, it was like scorched earth. It was a wasteland,” said Richard F. Ambrose, an ecologist at UCLA. “It was a cracked mass of mud and sewage. I could see what used to be there, and I saw it as an opportunity, but it’s a daunting task.”

In an unprecedented experiment, the scientists are testing native marshland plants to find which ones flourish in sludge. Using 2 acres, they recently planted nursery-raised seedlings into plots containing soil-sludge blends. The parcel resembles a big vegetable garden, with tiny sprigs of alkali heath, pickleweed and other plants poking out of the ground amid trestles and a man-made creek that connects the parcel to the ocean. It is the first time anyone has attempted to create a marsh from a sewage sludge pit in this manner.

If they find the right combination of plants and soil, fuzzy green marsh plants could spread over the sludge garden. And if that works--and the researchers emphasize that it is too early to tell--nearly the entire disposal area could be converted to marsh indistinguishable from the rest of Mugu Lagoon. Shorebirds and migratory waterfowl would follow, in which case California would have recovered a small but important piece of its diminishing wetlands.

“I see a new salt marsh and tidal creeks, birds feeding in mud flats, shorebirds feeding on invertebrates, and migratory birds breeding,” said Thomas W. Keeney, senior ecologist at the base, peering into a future of possibilities. “It’s critically important. We can put a lot of the ecosystem back together.”

Moreover, such a restoration has the potential to save millions of dollars in cleanup costs. Navy officials estimate the cost to reclaim the sludge pits at about $1 million, a fraction of what it would cost to dig up the muck and haul it away.

Marshes such as Mugu Lagoon, where Calleguas Creek empties into the Pacific, are increasingly rare in California. They are among the most biologically productive places on Earth, serving as breeding grounds and nurseries for fish, birds and insects, critical habitat for migratory waterfowl and giant nutrient sinks that capture sediments that form the foundation of rich and complex food chains.

Most marshes have been turned into golf courses, condominiums and marinas. California has lost about 93% of its original wetlands, more than any other state, according to scientists and government officials. Yet within the guarded confines of the Navy base, 2,000 acres of quality estuary make up the largest remaining saltwater marsh between San Francisco and the Mexico border.

Each year, tens of thousands of migratory birds, 312 species in all, pass through Mugu Lagoon on their sojourn along the Pacific Flyway. Ducks, terns and plovers are among the avian visitors. Ten threatened or endangered species depend on the lagoon.

“The whole Oxnard Plain used to be wetlands, but we turned it into farms,” said Reed Smith, former conservation chairman of the Ventura County Audubon Society. “Anything that can be converted back into wetlands is a good idea.”

Much of Mugu Lagoon was sacrificed to build the military base. As the base grew, a spot of land on a bend in the creek was cleared for waste-water disposal. The Navy’s sewage plant operated until 1991, when waste water was diverted to Oxnard for treatment. Sludge in the ponds sat for years until inspectors discovered that the pits were leaking about 100,000 gallons of waste water into the lagoon daily.

Tests showed that the sludge was contaminated with a variety of heavy metals, including chromium and lead, from industrial wastes flushed down the drain. The concentrations were sufficient to require action, but not enough to be considered an acute hazard.

Cleanup proceeded in fits and starts until March 1998, when the Los Angeles Regional Water Quality Control Board issued an order putting the cleanup on a fast track.

At first, authorities contemplated putting a dirt cover over the sludge or hauling it to a landfill at a cost of up to $50 million. Those costs were deemed too high, and the Navy began looking for another solution. Enter the UCLA researchers.

Ambrose and colleague Richard R. Vance were shopping the California coast in search of sites where they could study salt marsh ecology when they happened upon the naval base. Keeney told them about the sewage sludge problem, and the recovery project was born. “It was serendipity in science,” Ambrose recalled.

Of paramount concern was coming up with a strategy that leaves the sludge in the ground to minimize the risk of spreading pollution. Spreading sludge to the land like fertilizer was rejected when the researchers learned that when that approach was used at an East Coast marsh, it spread pollutants into waterways during storms.

“We don’t want to be responsible for causing an environmental disaster,” Ambrose said.

The research team decided to explore ways to grow the marsh plants directly on top of sludge mixed with soil. But there were three big hurdles to overcome.

First, they had to find out if native plants would take to sludge. A pilot test in 1997 with 280 potted plants showed they could grow, provided plenty of sand and soil were added.

Next, the scientists must figure out which blend of sludge, dirt and plants will produce optimum growth. And, finally, they must ensure that once plants begin growing in the sludge, the metals will stay put and not accumulate in the tissues of plants and animals living in the marsh. The experiment now underway should go far toward answering those questions.

Scientists finished planting 10,000 seedlings in a mix of soil types at the 2-acre study site in December. To their horror, hot Santa Ana winds late that month scorched the tiny, tender shoots poking out of the sludge. The Navy turned on fire hoses and kept the site moist until rains came.

For the rest of this year, and possibly next year, scientists will watch how the plants grow and test the soil for changes in metal concentrations. If the results are favorable, all of the sludge pits could be made ready for planting and a marsh could rise from the muck.

“Letting the wetland reclaim it is probably the best approach, but it’s not an overnight solution,” said John Geroch, manager of the project for the regional water quality control board.