4/6/2016 - Perchlorate Information for PSA Customers

Montgomery County Public Service Authority (MCPSA) is committed to providing the highest quality water service to its customers and the citizens of Montgomery County. To illustrate this commitment, the MCPSA Board of Directors conducted perchlorate testing from the two MCPSA water systems currently supplied by wells; Woodview and Riner. This testing was in response to recent concerns raised by citizens based on possible releases from the Radford Arsenal.

The perchlorate test result for the single well supplying the Woodview water system was 0.53 micrograms per liter. The test results for the three wells supplying the Riner water system were below the detection level of 0.20, 0.42, and 0.67 micrograms per liter. Micrograms per liter are also expressed as parts per billion and, in perspective, one microgram per liter is the same as 1 inch in 16,000 miles.

There is a considerable amount of information available on perchlorate from numerous sources. The Environmental Protection Agency (EPA) and Agency for Toxic Substances and Disease Registry (ATSDR) appear to be the most comprehensive. The EPA Technical Fact Sheet – Perchlorate, dated January 2014, includes basic information on perchlorate while the ATSDR Toxicological Profile for Perchlorate, dated September 2008, studied health effects of perchlorate.

In the EPA Fact Sheet, the EPA established an Interim Lifetime Drinking Water Health Advisory of 15 micrograms per liter (µg/l), which is a concentration of perchlorate in drinking water that is not expected to cause any adverse non-carcinogenic effects for a lifetime of exposure. They also noted that numerous states have promulgated enforceable standards in drinking water and cited examples in Massachusetts (2µg/l) and California (6µg/l). In addition, at least 10 other states have also developed advisory levels or health-based goals ranging from 1 to 18µg/l for drinking water and 1 to 72µg/l for groundwater.

ATSDR issued a response to comments received during the recent RAAP permit reissuance process relative to perchlorate sampling of private wells (not affiliated with the most recent samples requested by the MCPSA) adjacent to the RAAP that yielded results of below detection level, 0.529, 0.285, 0.357 and 0.387µg/l. The ATSDR response included the text, “The recent detections of perchlorate in 4 of 5 offsite private wells are all very low (less than one microgram per liter). These detections are lower than ATSDR’s health based screening level for perchlorate in drinking water of 7 micrograms per liter… The source of the low levels of perchlorate in private wells is not known, but the concentration of perchlorate in these wells is within the range of perchlorate in a survey of “pristine” sites across the United States. Because the concentrations detected are below ATSDR’s health screening level, there is no public health basis for recommending additional testing.”

The finding of trace amounts of perchlorate in MCPSA wells required extensive evaluation of the issue to ensure the safety of public health and drinking water quality. The trace amounts found were below every health based advisory, goal, level or standard and, as such, does not pose a health concern.


Robert C. Fronk, PE
PSA Director


Montgomery County
Government Center
755 Roanoke St. Ste. 2I
Christiansburg, VA 24073

Phone: (540) 381-1997
Fax: (540) 382-5703
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