TRPA recommends ban on two-cycle engines | TahoeDailyTribune.com
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TRPA recommends ban on two-cycle engines

Patrick McCartney

The Tahoe Regional Planning Agency’s governing board recommended a ban from Lake Tahoe on all old-technology two-cycle engines by 1999 late Wednesday, but will prepare an ordinance and discuss it at its June meeting.

The action, if adopted in June, would go farther than regulating personal watercraft because of concern with fuel emissions from all two-cycle engines. The board is also considering adoption of no-wake zones that would keep watercraft farther from shore and minimize disruption from their noise.

The board listened to impassioned testimony from the owners of watercraft rental firms, environmentalists, residents – all who had something to say about the possible impact the popular but noisy water scooters have on Lake Tahoe. While much of the debate centered on the crafts’ alleged pollution of Lake Tahoe’s water, it was complaints over noise and safety that first made personal watercraft an issue for the agency.



The board had to sift through hours of often-conflicting testimony by experts recruited by both sides of the debate.

Proponents of a ban on personal watercraft had two transportation officials testify from Berne, Switzerland by satellite hookup. The pair explained the reasons why Switzerland prohibited the type of two-cycle engines that power personal watercraft from its lakes.



Gerhard Kratzenberg said studies showed more fuel emissions remained in the Alpine lakes than the industry claimed, and that laboratory tests reported high mortality rates of the type of zooplankton that live in Lake Tahoe.

John Giesy, a fisheries and wildlife professor from Michigan State University, described how the presence of ultraviolet light greatly increases the toxicity of certain engine emissions, a finding that could have repercussions at Lake Tahoe, which receives more ultraviolet light because of its altitude and the clarity of its water.

“To us, Lake Tahoe would be a worst-case scenario,” Giesy said.

But experts testifying for the marine manufacturing industry downplayed the problem of emissions from personal watercraft.

Ted Morgan, director of engineering for Mercury Marine for 29 years, disputed claims that a significant amount of unburned fuel is discharged into the water. According to a 1973 study, Morgan said just 1 percent of the fuel consumed by personal watercraft finds its way into the water, not the 25 percent or more that is part of the crafts’ exhaust.

“Only a fraction of the hydrocarbons remain in the water,” Morgan said.

Another industry witness, aquatic toxics expert Bill Stubblefield of Colorado State University, said much of the gasoline that enters the lake evaporates within a short period, based on studies of oil spills. Stubblefield added that no research exists that reveals whether or not a problem exists at Lake Tahoe.

And the industry also surveyed 10 water providers in the Tahoe Basin, none of which reported detectable levels of gasoline compounds in water drawn from the lake.

But Charles Goldman, head of the Tahoe Research Group, said the public should be concerned with the fuel that enters the lake, whether discharged directly into the water or into the atmosphere first.

“We have a lake with a small surface-to-volume ratio,” Goldman said. “What gets into the water doesn’t get exposed to much evaporative loss.”

Underlying the issue of watercraft emissions is the inefficiency of the two-cycle engines, said Gerald Rosenbluth, an Arizona consultant who is an expert on automobiles for that state’s attorney general’s office.

He described two-cycle engines as 1949 technology that has not been modernized. But a fuel-injection system that would reduce emissions by three-fourths has been available for 20 years, he added.


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