Thursday, Jan. 8, 1998 | 6:33 a.m.
The Southern Nevada Water Authority said December testing showed perchlorate levels of 16 parts per billion (ppb) in the raw water supply and 14 ppb in the finished water.
The state of California has established an advisory level of 18 ppb in drinking water because of concerns that high levels of perchlorate can interfere with the function of thyroid glands. There are no national or Nevada levels for perchlorate safety.
Water officials blame a seasonal turnover of Lake Mead water for the increase in levels from 11 ppb found in July testing of the water that is used in Las Vegas.
Until April 1997, laboratories were unable to test for perchlorate levels under 400 ppb. Officials said someone would have to consume 1,470 gallons of water a day before the levels would have any noticeable impact on thyroid function.
Two companies that have manufactured the rocket fuel oxidizer on a Clark County-owned island near Henderson for more than 40 years have submitted plans to clean up the perchlorate, and a report is anticipated in May on ways to rid the drinking water of perchlorate.
The companies are also expected to isolate sources of the contamination on their property.
Normally such environmental cleanup takes years, but the companies are cooperating with the state.
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