LAKE TAHOE, Calif.—Scientists are planning to lay reinforced butyl rubber mats weighing more than 32 metric tons on the bed of Lake Tahoe in an effort to control the spread of Asian clams. The invasive clams threaten the lake's health and famed clarity, scientists said.
The barriers will be trucked to Lake Tahoe and, beginning Oct. 22 weather permitting, will be placed by divers onto a five-acre area on the floor of the lake's Emerald Bay.
Scientists, staff and students from the University of California, Davis are in the final stages of assembling the mats and enhancing them with rebar, brass grommets and valves that will hold the barriers in place underwater and enable scientific analysis of the project.
UC Davis, the University of Nevada, Reno, and a team of inter-agency partners first tested the concept of using rubber barriers to smother Asian clams in 2010, when scientists placed an acre of the barriers on the lake bottom. The project killed 100 percent of the clams. The success of those efforts and additional research led to this bigger project.
The technique is to lay organic material on the affected areas of lake bed, then place the mats on top and finally weigh them down with reinforcing steel bars. The aim is to deprive the clams of oxygen. As the organic material decomposes, it absorbs oxygen which cannot be replaced because of the impermeable nature of the mats. This kills the clams.
Each roll of rubber mat is 100 feet long, weighs 136 kg and is made from butyl rubber. There are 238 rolls altogether, held together with a total of 16,000 grommets.