Wednesday, April 23, 2014

Tahoe clam control begins

Photo 1 - Barrier Deployment ec

A SCUBA DIVER covers clams with a fancy wet blanket in a 2010 pilot project at Marla Bay in Lake Tahoe. The blanket smothers the clams. File photo courtesy Tahoe Regional Planning Agency

From page A1 | October 31, 2012 | 4 Comments

On Tuesday, scientists from UC Davis and the University of Nevada along with officials from different state agencies and planning agencies, gathered to view the largest Asian clam control project in the history of Lake Tahoe.

The goal of the project is to rid the lake of the clams before they spread. The clams live on a shallow, gravel sill roughly 15 feet below the surface that partially separates Emerald Bay from Lake Tahoe.

The program includes treating an area of up to 5 acres at the mouth of Emerald Bay by covering the infested lake bottom with thin rubber barriers, augmented with organic material made of Aspen fiber, to reduce the available oxygen and smother the clams.

Valves are built into the barrier material and serve as a port, allowing divers to insert a syringe and collect water samples from under the mat without disturbing the project.

Kristi Boosman, who is the public information officer for the Tahoe Regional Planning Agency said it will take four to six weeks to lay the barriers, which will remain in place for a year. The barriers are being laid now because boat traffic on the lake is lower this time of the season.

According to UC Davis, controlling the Asian clam population at Lake Tahoe is critical because of their negative impact in creating greater calcium concentrations, which increase the potential for other species like quagga mussels to live in Lake Tahoe. They promote the growth of algae that impacts the scenic beauty of the shoreline by changing the water color, reducing water quality, and washing rotting materials onto the beaches. They also compete with native animals for habitat and food.

“Emerald Bay is an iconic location and currently is one of the most photographed areas of the world,” said Boosman.

Funds for the $810,000 clam removal project came from the Lahontan Regional Water Quality Control Board, U.S. Forest Service, U.S. Fish and Wildlife, and the Southern Nevada Public Land Management Act.

Boaters are warned to stay 200 feet away from the dive flags and barge at the mouth of Emerald Bay to avoid endangering the divers. Work is primarily being done during early morning and on weekdays, with no work occurring on the weekends or holidays in order to reduce boater inconvenience. A TRPA boat will be on hand to help direct boat traffic in and out of Emerald Bay during the installation.

Scientists from UC Davis and the University of Nevada, Reno, first devised and tested the concept of using rubber barriers to smother Asian clams in 2009-2010, when they placed an acre of the barriers on the lake bottom at Marla Bay and Lakeside. The first-of-its-kind method killed 100 percent of the clams.

The success of those efforts and additional research led to the project currently under way, which involves a team of 40 interagency partners including federal, state and local jurisdictions, research partners, public utility districts, and private marinas.

TRPA estimates there are 100 acres of clams in the lake. Boosman said they are developing a long-term strategy for treating the lake and raising additional funds to complete the project.

The clams were first discovered in 2002 but it wasn’t until 2008 that different agencies recognized the problem and came together to solve it. Boosman said they suspect that the clams were unintentionally introduced into the lake by a boat that brought them in from another water body. The introduction of the clams and other harmful species into the lake has led to stepped up boat inspections at Tahoe.

Contact Dawn Hodson at 530-344-5071 or Follow @DHodsonMtDemo on Twitter.


Discussion | 4 comments

  • cookie65October 31, 2012 - 3:29 am

    Is there a plan to remove the dead clams or to just let them decompose creating a negative effect on water clarity which will be blamed on human activity in order to secure even more taxpayer money?

    Reply | Report abusive comment
  • Phillip VeerkampOctober 31, 2012 - 11:00 am

    cookie65 - The actual mass of decomposing organic clam flesh represents a miniscule portion of naturally occurring fish feces dead and decomposing fish, frogs, turtles, ducks and geese. Fear not, cookie.

    Reply | Report abusive comment
  • cookie65October 31, 2012 - 8:01 pm

    Phil, how many millions have those "miniscule portions" and "natural occurances" cost us so far? The leftist agenda is not based on reason, logic or science. My only fear is people who don't understand that simple truth. They have the power to elect people like obama.

    Reply | Report abusive comment
  • Phil VeerkampOctober 31, 2012 - 11:56 pm

    OK, Cookie. I'll . . . . . . . . . . . . clam up.

    Reply | Report abusive comment


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