Aquatic weed threatens Discovery Bay

November 9, 2010 7:23:41 PM PST
What was once simply a popular aquarium plant has now become an invasive aquatic weed that is so pervasive it is threatening to choke off parts of the delta.

It litters the otherwise pristine bays of Discovery Bay, its long mangy tentacles rising to the surface, fouling the water at nearly every turn. Called egeria densa or "brazilian waterweed," it is an invasive weed that many fear could someday take over the delta.

"Egeria is basically an aquarium plant that was probably released via accidental aquarium dumping or someone trying to release their aquarium pets to try to kind of save them and put them in the wild and they don't realize the impacts to the environment," San Francisco Estuary Partnership spokesperson Karen McDowell said.

Now, with stems rooted as deep as 20 feet, egeria is not just a nuisance; it has become a danger to delta boaters, swimmers and the fish and wildlife that depend on the waterways.

"It totally changes the fish habitat," McDowell said. "Some of it is so crowded, the larger fish can't even swim into that area."

This past summer in parts of Discovery Bay, the egeria densa became so thick homeowners paid for a mechanical harvester to come in and cut back the plants. Then, they put up special buoys to try to keep it from coming back.

In other areas, homeowners have come up with their own methods for fighting back.

"This is the first year that we've seen it like this, to where now it's really starting to come up at low tide, you just see it," resident Richard Clark said.

Egeria densa is so hearty, so pervasive and insidious, that the efforts of individual homeowners provide only temporary relief.

"I'm afraid when it gets so bad, it's going to be like the Wild West Show; they're going to do whatever they want, they're going to throw chemicals in, bleach in, gas in," Reclamation District 800 spokesperson Jeff Conway said.

That is why Contra Costa County officials have joined with other local and state agencies to form an invasive weed task force.

"We need to keep the agencies at the table, we need to work very hard on advocacy, on legislative intent and language to give the Department of Boating and Waterways the power and authority to work more comprehensively on the issue," Contra Costa Supervisor Mary Piepho said. "And funding, funding's critical."

Lenora Clark is a longtime Discovery Bay resident who serves as a commissioner for the California Department of Boating and Waterways. She says this year is the worst she has seen.

"The plan going forward is going to be a combination of trying to harvest a lot of it in the very beginning in April and then apply a herbicide that has been approved for the area and won't damage the water and the environment," she said.

It is a plan that will require at least $2-$3 million in funding from a state that may not have it to give.

A solution cannot come soon enough for those most impacted by the insidious plant. In Cabrillo Bay in Discovery Bay, the weeds have grown so thick that in some places, folks have a hard time getting their boats out of their slips.


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