Older jet skis dump gas into lake water
By Teresa Crawford, Outpost staff
Earlier studies by the USGS and Tahoe Research Group from University of California, Davis, in Lake Tahoe and nearby Donner Lake confirmed that marine engines shed fuel into the lakes. The experiment this year fingered the culprit responsible for most of the pollution: the carbureted 15-horsepower, two-stroke engine that powers small outboards and the Sea Doo, a zippy little machine with a great power to weight ratio.
"The two-stroke models are the absolute dirtiest," Miller, director of the Environmental Health and Sciences graduate program at University of Nevada, Reno, said.
Because of an open valve between the fuel intake and exhaust chambers, the engines inject almost 30 percent of their scalding gas into the water. Some of it puffs out the machines' tail pipes as black smoke.
"The most significant finding we had this summer is that the findings were unremarkable," Miller said. "It's just what you would expect."
He warned that the personal watercraft industry shouldn't take the news as an endorsement for any of their products, including the four-stroke engines that release much less gas.
"This is not a clean bill of health for personal watercraft," Miller said. "All it says is the newer ones are less polluting than the older ones."
The affable smile that Miller wears as comfortably as his knee-wrinkled suit disappeared when he was asked how these findings would affect the marine manufacturers' lawsuit against the Tahoe Regional Planning Agency for its June 1999 ban of two-stroke engines.
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The original suit was dismissed Oct. 2 in the U.S. District court in Sacramento, Calif. A new complaint filed Oct. 16 disputes the ban on grounds that it discriminates against users of two-stroke engines. The complaint also contends that the ban was based on opinion about pollution by the engines rather than environmental analysis, although preliminary word of Miller's findings was available.
"We can't get rid of the watercraft, but our data can help minimize the impact," Miller said. "The planning agency can make a decision based on what we've done. The results bolster their argument for a ban."
He said that the only real surprise of the research was that the team could not find any near-shore area free of the gasoline constituents they tested: toluene, xylene, benzene and MTBE.
Peaceful Kings Beach awaits a summer free of two stroke jet skis. Photo by Teresa Crawford |
"Maybe waters with no background levels of benzene and MTBE are out there, but every place we could run the boats already had some contamination," Miller said. "But gas in the lake is a time-limited issue. It mostly vaporizes out days or weeks after the boaters leave for the summer."
Miller said his work won't help with the research focused on slowing the lake's loss of clarity. Gasoline doesn't have much to do with the explosive overgrowth of algae that threatens to cloud the blue waters.
So what is the issue of gasoline in Lake Tahoe?
"It's a values issue," Miller said. "How much gas do you want in there? In some places, the benzene level is one part per million, California's threshold, although that's low.
"Some people, like my wife, think the noise issue is a stronger argument for regulating them. It really detracts from the pastoral experience."
Posted Oct. 27, 1998
Copyright 1998 Nevada Outpost
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