My Turn: Asian clam threat to Lake Tahoe
Special to the Sun
The image conjured by Sen. Dianne Feinstein’s observation at the recent Lake Tahoe Summit that and#8220;If you organized all the Asian clams currently in the lake end to end, it would stretch 3.5 miles long,and#8221; was both humorous and foreboding, and it raised the questions of just how much of a threat Asian clams are to the lake and how effective current and planned control efforts will be.
A single-file, three and a half mile long column of clams would assuredly be an amusing sight, but since the nickel-sized clams would only cover a total area less than half of that of a tennis court they would not present an imposing sight. And this may explain the misbegotten belief that they will be easy to eliminate or to control and#8212; after all how hard can it be to eliminate 1,500 square feet of clams?
Since first discovered more than 70 years ago in Washington’s Columbia River, Asian clams have spread to 38 states with the greatest concentrations found in the warm, nutrient-rich water of the Southeast. After once being introduced, there is no case of Asian clams being eradicated from any sizable body of water. In many areas the clams are thought of as a benign species. Indeed, the U.S. Geological Survey says that they are and#8220;consumed mainly by fish and crayfish and#8230; (and) results indicate that several local fish species have modified their diet to feed on invasive molluscan species such as C. fluminea (Asian clams).and#8221;
The USGS also reports and#8220;the most prominent (environmental) effect of the introduction of the Asian clam into the United States has been biofouling, especially of complex power plant and industrial water systems. It has also been documented to cause problems in irrigation canals and pipes and drinking water supplies. It also alters benthic substrates (the lake bottom), and competes with native species for limited resources.and#8221; Because Asian clams cover approximately 0.0000002 percent of the lake bottom, these environmental effects do not seem to be of even remote concern to Lake Tahoe.
A July 9, 2010, press release by the Tahoe Regional Planning Commission states that a and#8220;$1.4 million effort by a collaboration of federal, state and local agencies called the Lake Tahoe Asian Clam Working Group to eradicate the Asian Clam,and#8221; has been formed. And as part of the effort to control the clams first identified in the lake eight years ago, the Tahoe Resource Conservation District is managing a $648,000 project that and#8220;involves laying up to an acre of thin rubber matting on the lake’s bottom at two sites in the southeast region of Lake Tahoe in order to kill the clams by starving them of oxygen.and#8221;
In the same press release TRPA says, and#8220;Aquatic invasive species pose a serious threat to Lake Tahoe and this project is part of the multi-agency effort to protect the Lake’s delicate ecosystem and#8230; (and) this project is a crucial step in taking control of the Asian clam infestation that we have watched spread recently.and#8221;
The press release further stated that Asian clams and#8220;current known distribution (area ~1 million square meters (250 acres)) is patchy along the southeast shore from Zephyr Cove, Nevada to El Dorado Beach, California.and#8221; Assuming TRPA’s estimates are accurate, that the clams do not appreciably spread, that the current project is successful and works at depths greater than the 15 foot average depth of the initial project, and that the cost per acre to kill Asian clams remains constant, Lake Tahoe will be the first success story in controlling Asian clams and#8212; and at a cost of only $160 million.
It appears that along with Nevada Sens. Harry Reid and John Ensign, Sen. Feinstein’s life-long love and filmy memories of summers at Lake Tahoe as recently described by the Sierra Sun have clouded her good judgment of how her influence and of how federal money can best be used to preserve the ecology of the lake.
and#8212; Steve Urie is a Truckee resident.