Arkansas Department of Health
Center for Local Public Health - Environmental Health Branch - Engineering Section

On January 16, 2000, the television news magazine 60 Minutes featured a report on the presence of MTBE in drinking water. This report has raised a number of questions about MTBE and Drinking Water in Arkansas. Those questions, and the Health Department's response, is below. Additional information may be found at EPA's web site, www.epa.gov/safewater/mtbe.html.

Is the presence of MTBE in Drinking Water considered a violation of drinking water standards?

 

No, the presence of MTBE does not constitute a violation of state drinking water standards. Arkansas uses the National Primary Drinking Water Standards for its state standards. These standards are developed by EPA, and the standards do not currently include MTBE. EPA is investigating MTBE as a possible candidate for regulation in a future round of regulations. There is insufficient health effects information for EPA to make a decision at this time.

Are public drinking water supplies in Arkansas being checked for MTBE?

No, at the present time there are no routine analyses of MTBE being conducted on public drinking water supplies in Arkansas. Because of the expanding evidence of widespread presence of MTBE in groundwater around the country, the Department has investigated the possibility of conducting such analyses as part of its routine monitoring of public water systems sources. Difficulties associated with performing the analyses prevent the Department from conducting MTBE analyses utilizing existing laboratory equipment and space. The Department is preparing a new analytical area that will allow for the analyses of MTBE. Once the facility and equipment are fully operational, the Department will begin including MTBE in its routine analyses of community public water systems.

Has MTBE been found in ground water in Arkansas?

Yes, MTBE has been found in conjunction with the investigation and remediation of leaking underground gasoline storage tanks. As part of their investigation, staff of the Arkansas Department of Environmental Quality (ADEQ) sample soil and ground water, and the samples are then tested for gasoline components, including MTBE. Almost every leaking underground storage site that has been investigated recently has been found to have MTBE present in the soil or groundwater.

Has MTBE been found in drinking water in Arkansas?

There have been no routine analyses for MTBE in public drinking water in Arkansas, so no MTBE has been found in public drinking water, except in conjunction with a leaking underground storage tank investigation. Investigations have detected MTBE in the water supply of a small mobile home park, and one of the wells used by a non-transient, non-community water system serving a recreational lodge. Gasoline components have been detected in one other public water systems in recent years. It is presumed that MTBE would have been found in these cases, if the analysis had been conducted.

In Garland County, an investigation into a leaking underground storage tank caused the analysis of water from the Hummingbird Estates water system. MTBE was detected. The levels found are above the threshold taste and odor level, but below the level of concern for short term health effects. The water system is in an area scheduled to be served by a regional water source currently in the development stage.

In Randolph County, students at the Oak Ridge Central School district noticed the odor of gasoline in the school’s water supply. The source of the gasoline was quickly identified as a nearby leaking underground storage tank that had previously been abandoned. The site was remediated, and modifications to the water supply well have essentially prevented any remaining gasoline contamination in the soil from contacting the water being pumped from the well.

In Ashley County, a single sample in 1997 showed the presence of gasoline components in a water supply well used by the Town of Wilmot.  A leaking underground storage tank was located in the vicinity of the well. Regular analyses have been conducted over the past several years without any additional detection of gasoline components in the water supply.

In Benton County, the discovery of an underground storage tank caused the Department to analyze two wells utilized by the Copper Mine Grocery, a transient non-community water system. One of two wells was contaminated by gasoline components. The well was abandoned and no MTBE or other gasoline was found in the second well.

What are the impacts of MTBE in terms of health and water quality?

The Environmental Protection Agency is currently investigating the health effects of MTBE to determine if there should be a national drinking water standard for the compound. Generally, a drinking water standard is established when there is widespread presence of the compound in public drinking water, and there are known or suspected health effects at the concentrations found in drinking water? Since there has been very little monitoring for MTBE in most states, the occurrence data is pretty sketchy. Likewise, EPA has insufficient health effects data to make a regulatory determination. For the first reason, EPA has included MTBE in the Unregulated Contaminated Monitoring Rule, which becomes effective January 1, 2001. EPA has also commissioned a panel of experts to examine the health implications. A Health Advisory issued in 1997 is available at EPA's web site Drinking Water Advisory - Consumer Acceptability and Health Effects Analysis . This document indicates that there should be no adverse health effects at levels below the taste & odor threshold of 20 to 40 micrograms per liter (parts per billion).

For more information about environmental monitoring for MTBE in Arkansas, you may contact the Mike Shinn, P.G., with the Regulated Storage Tank program at the Arkansas Department of Environmental Quality - 501/682-0989.