MTBE levels drop in Alpine County
The levels of MTBE in Alpine County’s Harvey Place Reservoir have decreased since the additive was first discovered there, and officials plan to release the water as usual this spring.
“We’re elated,” said Chris Gansberg, member of the Alpine County Board of Supervisors.
MTBE levels in the 100-acre irrigation reservoir were about 0.6 to 0.9 parts of the additive per billion parts water upon discovery in January. The South Tahoe Public Utility District received lab results this week from tests performed in the middle of March. MTBE levels ranged from 0.3 to 0.4 parts per billion.
“It’s about half of what it was when we discovered it,” said Bob Baer, general manager of STPUD. “If you cut that in half again, you probably won’t find any there.”
All of the levels were below California’s public health goal of 13 parts per billion.
“Even with how it was before, there wasn’t a real concern,” Gansberg said. “But if that would have stayed the same or gotten worse, then we would have been very concerned.”
STPUD – which provides sewer and water service to most of South Shore’s residents – transports its recycled water through a pipeline 26 miles to the reservoir, where the water is used to irrigate more than 2,000 acres of ranch land over the summer.
By state law, STPUD is not permitted to release any of its recycled water into the basin. It is high in nutrients that ultimately would lead to algal growth in Lake Tahoe.
Several South Shore gas stations have plumes of MTBE coming from their facilities. In their clean-up efforts, some stations pump contaminated water out of the ground, treat it with a carbon filtration system and pump the clean water into the sewer system. However, “breakthroughs” can occur, meaning MTBE contamination can slip through into the sewer system. That is how the contamination is believed to have reached the reservoir. Since then, STPUD has taken steps to ensure more breakthroughs don’t happen.
In recent summers, several researchers have found traces of MTBE at various levels in Lake Tahoe. Those levels decline and disappear in the fall. STPUD officials had hoped the results would be similar for Harvey Place, with the MTBE dissipating before summer when the ranchers use the water.
“That’s our hope, and it seems to be responding the way Lake Tahoe does,” Baer said.
Ranchers start using the water stored in the reservoir for irrigation sometime between April 15 and May 1. Baer said the water would be released at its usual rate this year.
MTBE – methyl tertiary butyl ether – is a fuel oxygenate comprising significant portions of California gasoline. It is classified by the U.S. Environmental Protection Agency as a possible cancer-causing agent, and last week California Gov. Gray Davis ordered that its use be phased out by 2002.
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