Boaters Alerted of Asian Clam Control Project in Emerald Bay

Lake Tahoe, CA – Boaters heading to Lake Tahoe in the next 6 weeks may experience a short delay
when entering Emerald Bay due to an Asian clam control project that will be taking place there.

The Asian clam control project is being implemented by a team of partners from the Lake Tahoe
Aquatic Invasive Species Program, with plans to treat an area of up to 5 acres at the mouth of
Emerald Bay. Treatment will be accomplished by covering the infested lake bottom with thin
rubber barriers, augmented with organic material, that reduce the available oxygen and smother
the clams. It will be the largest project of its type in the history of Lake Tahoe.

The Asian clam control project is scheduled to begin on October 17 (weather permitting) and the
deployment of bottom barriers will take from 4 to 6 weeks to complete. A TRPA boat will be on
hand to help direct boat traffic in and out of Emerald Bay during the installation.

Boaters are advised to use extra caution when entering Emerald Bay during this period and to avoid
endangering members of the dive team. Blue and white or red and white dive flags will be used by
agency personnel to indicate that divers are in the water, at which point boaters are required to
stay at least 200 feet away from the dive and project area. Boats entering or exiting Emerald Bay
between the hours of 5 a.m. and 11 a.m. may be subject to short delays in order to ensure safe
passage for the divers and control vessels.

“This is a physically demanding undertaking. The project team is laying down over 4 miles of
barriers, in very cold water at the mouth of Emerald Bay where water currents are known to
fluctuate rapidly,” said Dr. Geoffrey Schladow, Director of the UC Davis Tahoe Environmental
Research Center. “Boaters are urged to help the effort by keeping a safe distance and following the
directions of the guide boat.”

The barriers will be left in place for approximately one year in order to achieve clam mortality.
Crews will return for three weeks in the fall of 2013 to remove the barriers. Work will primarily
occur during early morning and on weekdays, with no work occurring on the weekends or holidays
in order to reduce boater inconvenience.

Currently, the clams live on a shallow, gravel sill approximately 15 feet below the surface that
partially separates Emerald Bay from Lake Tahoe. The Asian clam infestation at Emerald Bay is in
the early stages of invasion and currently small enough to manage through an effective prevention
and control program. Recent scientific research has shown that the use of bottom barriers is
effective at controlling Asian clam infestations in Lake Tahoe. Without treatment, the population
can grow rapidly and become extremely difficult and expensive to control.

“The Tahoe Resource Conservation District is proud to be a part of this broad collaborative effort
and do our part in preserving the beauty and majesty of Emerald Bay,” said Jim Brockett, AIS
Control Project Coordinator with the Tahoe Resource Conservation District. “We urge boaters to
be safe and observant as our divers deploy the clam-killing barriers that will help protect Lake
Tahoe from this invasive species.”

Controlling the Asian clam population in Lake Tahoe is critical as the clams have a variety of
negative impacts. The clams could increase the potential for other species such as quagga mussels
to establish in Lake Tahoe by increasing localized calcium concentrations. They also promote the
growth of algae by releasing highly concentrated nutrients. Increases in algae impact the scenic
beauty of the shoreline by changing the water color, reducing water quality, and washing rotting
materials onto the beaches. Perhaps most significant, Asian clams compete with native animals for
habitat and food, which causes a disruption in the food web. By treating the Emerald Bay
infestation in the early stage, these impacts can be minimized or avoided. The treatment will also
help prevent the spread of these invasive clams to other areas of Lake Tahoe.

“Preserving the exceptional boating and recreation opportunities in Emerald Bay State Park is
important to us,” said Dan Shaw, Environmental Scientist for the California Department of Parks
and Recreation. “We are asking the boating community to exercise caution and a little patience
when enjoying Emerald Bay for the next month.”

The Lahontan Regional Water Quality Control Board, U.S. Fish and Wildlife Service, California
Department of Parks and Recreation, and the Tahoe Regional Planning Agency are leading the
charge to control Asian clams in Emerald Bay. The U.S. Forest Service, Pacific Southwest Research
Station is funding continued research on the invasive clam infestation to monitor the effectiveness
of this control effort. The team of partners working on this project also includes staff from the
Tahoe Resource Conservation District, California State Lands Commission, Nevada Division of State
Lands, and researchers from the University of California Davis Tahoe Environmental Research
Center and the University of Nevada Reno.

The Lake Tahoe Aquatic Invasive Species Program consists of 40 public and private partner
organizations including federal, state and local jurisdictions, research partners, public utility
districts, and private marinas. This Program provides leadership, direction and resources to fulfill its
mission of prevention, detection and control of aquatic invasive species in the Lake Tahoe Basin.
For additional information, contact Kristi Boosman of TRPA at (775) 589-5230 or
kboosman@trpa.org.