Sedimental Journey : Dredging Could Protect Marshes of Newport Bay

It’s low tide along the northern shore of Upper Newport Bay and mounds of sediment form small islands that rise above the expanse of shimmering blue water.

This peaceful scene alarms environmentalists and marine officials alike, because it’s a graphic illustration of the problems caused by more than 300,000 cubic yards of silt, clay and sand that have accumulated in the scenic back bay over the last decade, transforming marshes into meadows and choking waterways.

In response, a group of county, state and local agencies have planned a major dredging project aimed at removing the sediment, as well as deepening a trap that catches materials as they flow into the bay from two storm channels.

But several obstacles stand in the way. The agencies have yet to secure funding for the $5-million dredging project. Moreover, officials remain uncertain whether they will be able to dump the silt and sediment at a site four miles off the coast of Newport Beach where previous dredging deposits were made.

Still, representatives from the county, Newport Beach and the state Department of Fish & Game say they remain committed to the project and warn of grave consequences if sediment is allowed to continue flowing to the bay unchecked.

The buildup threatens to fundamentally alter the local ecosystem, eventually turning portions of saltwater bay into freshwater prairie. Such a transformation would imperil much of the plant life, fish and rare birds that now inhabit the bay, including the endangered light-footed clapper rail.

“We’re going to lose the bay if we don’t do something,” said Robert G. Fisher, the county’s director of harbors, beaches and parks. “The upper bay is gradually turning into a meadow as it fills with more sediment.”

In many ways, the dredging project is a classic battle against the forces of Mother Nature. Experts said it’s perfectly natural for heavy storms to send sediment toward the ocean from mountains and flatlands.

“Every mountain is on its way to the ocean,” said John Wolter, a environmental consultant working on the project. “That’s the natural process.”

The process has been accelerated, however, because the tributaries flowing into Upper Newport Bay were converted decades ago into storm drains that carry larger amounts of runoff.

Despite the occasional cleanup costs, the public has long supported preservation of the 752-acre bay, as do nearby residents, some of whom enjoy sweeping views from the bluffs that surround the estuary.

“It’s an environmental issue . . . but it’s also an economic thing,” said Newport Beach Councilwoman Jean H. Watt, a veteran bay preservationist. “People, of course, bought homes around the bay. They don’t want to see it change.”

The last dredging took place in the mid-1980s, when officials also excavated two collecting basins designed to trap sediment as it flowed in from the San Diego Creek and Santa Ana-Delhi Channel.

But the traps are now full, and the record storms of 1995 have caused a variety of sediment problems around the back bay.

At the Newport Dunes marina, mounds of silt and sand blocked a channel, preventing some boaters from getting out of their docks during extremely low tides.

“People are very upset when they are not able to use their boats,” said Tim Quinn, general manager of the Newport Dunes Resort.

The county recently completed some emergency dredging that cleared the marina’s channels. But a more complete project is scheduled, said Larry Paul, manager of coastal facilities.

State, county and Newport Beach officials also want to move forward on a larger-scale dredging program that calls for the removal of sediment from the catch basins and the expansion of one of the sediment traps.

Supervisor Marian Bergeson, a longtime advocate of bay preservation, has been working with the state’s natural resources department to help find the $5 million needed to complete the project, and an additional $10 million to fund future dredging.

Two likely funding sources are the ports of Los Angeles and Long Beach, which could help with the Upper Newport Bay dredging in exchange for state permission to develop some of the wetlands near their harbors.

Even if money is found, officials still need to secure a place to dump the estimated 300,000 cubic yards of sediment. The county and the U.S. Geological Survey will soon conduct ocean-floor mapping at a dumping site four miles off the Newport Beach coast.

The site has been used to deposit debris from previous dredging efforts. But officials must first determine how more dumping would affect the sea life in the area. Paul said the sand and silt collected from the bay would probably not be suitable for use on beaches.

Despite the urgent need for action, officials said the sediment problem is actually improving because of the many collection traps they have installed inside channels and creeks that feed into the bay.

“We are going to have to do dredging from time to time,” Paul said. “But as the sediment trapping becomes more effective, we will do it less and less.”

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

Digging Deep

Upper Newport Bay will be dredged to deepen the basin holding silt that has washed down the San Diego Creek channel. Removing 700,000 cubic yards of sediment will increase the bay’s capacity to handle silt, reduce future clean-out frequency and restore habitat. There is no start date for the project.

*

Tidal Flow

The bay shoreline rises and falls with the tide, about 10 feet each day.

Restricted tidal flow

As sediment fills the basin, habitat requiring saltwater dries out. Species in those areas may die or be forced to relocate.

*

Normal tidal flow

Dredging the area will restore the original habitat.

*

Costs

The $5- million dredging project is one part of $127 million in proposed watershed improvements.

* Bay and San Diego Creek basin projects: $14,796,000.

* Upstream watershed projects: $112,270,000.

*

Fast Facts

How much is 700,000 cubic yards of silt? Some idea of the size:

* One cubic yard is equal to one ton.

* Enough to fill 35,000 dump trucks.

* Will take 350 barge trips from bay to ocean.

*

Removing Silt

1. As extended legs provide stability, a clam-shaped bucket drags along bottom, gathering silt. When filled, the bucket is raised by deck winches and emptied into barge.

2. Loaded barge is towed four miles southwest of Newport Beach; exact dump location is pinpointed via satellite.

Sources: John M. Tettemer & Associates, LTD. and World Book Encyclopedia; Researched by APRIL JACKSON / Los Angeles Times