Packard Grant Will Help Solve Elkhorn Slough Erosion Problems

December 15, 2005

Packard grant will help solve Elkhorn Slough erosion problems

BY BRIAN SEALS SENTINEL STAFF WRITER

MOSS LANDING — This really is a million-dollar question.

As waves roll into Elkhorn Slough they are deepening the main channel, eating away at the banks of inland waterways in the area and reducing marshlands.

During the past 75 years, marsh vegetation has declined by almost 50 percent, much of it accelerated by the opening of the Moss Landing Harbor in 1947. During the same time, tidal creek width has enlarged from an average of 8 feet wide to an average of 40 feet in length.

The problem is how to halt that trend without causing unintended effects.

"This is a tremendously vexing problem," said Mark Silberstein, executive director of the Elkhorn Slough Foundation. "It's hard to solve."

A consortium of groups has been awarded $1.2 million from the David and Lucile Packard Foundation and from the Resources Legacy Fund to study the problem during the next three years and find remedies for the slough system, which begins at the mouth of the Moss Landing Harbor and winds behind the area of PG&E's power plant in Moss Landing.

"This gives us the opportunity to tackle the problem in a holistic way," Silberstein said.

In a search for solutions, the foundation will be joined by the Elkhorn Slough National Estuarine Reserve, Cal State Monterey Bay an the Monterey Bay Aquarium Research Institute.

Part of the mission is environmental — researchers want to preserve an ecosystem that features more than 340 bird species, 100 species of fish and is California's second-largest tidal salt marsh.

Another part of the effort is aimed at preserving infrastructure like the rail line that runs across the slough and a wheelchair accessible ramp at Kirby Park that is threatened by erosion.

Just what the actual fix will be remains to be seen. Once the research teams develop a plan, it would have to pass muster with a string of regulatory agencies.

At one time a solution was floated that would have placed a large rock sill at the entrance of the harbor, Silberstein said. Again, that raised questions about water quality, and such a structure could have interrupted fish migration in and out of the slough.

Finding a solution will be as complex as the slough ecosystem itself. Researchers will look into detailed models of water-flow patterns, chemistry and the social and economic effects of any measures that may be taken.

The erosion was accelerated by construction of the Moss Landing Harbor in 1947.

"Opening the harbor basically reset the clock for Elkhorn Slough," Silberstein said.

However, a series of human interactions has contributed to the loss of marsh lands. Beginning in the 1870s and through the 1950s, levees and dykes were built that restricted natural water flow.

In 1908, the Salinas River was diverted away from the slough, taking with it an infusion of freshwater that formerly flowed into the slough. And when the harbor was built, the opening allowed ocean water to rush in; formerly the mouth of the slough was slightly north of what is now the harbor entrance and that provided a bit of a shock absorber to waves from Monterey Bay.

If left unattended, the slough's main channel and creeks would continue to widen and diappaer over the next 50 years, a team of scientist convened in 2004 concluded.

"Our goal is to develop and implement an approach that will protect Elkhorn Slough for the long run," said Barb Peichel, project coordinator with the Elkhorn Slough National Estuarine Research Reserve. "It needs to be based on sound science, needs to be economically feasible and needs to be supported by the community."

For more information, visit www.elkhornslough.org.

Contact Brian Seals at [email protected].