| |
Good morning Mr. Chairman, and Members of the
Subcommittee. I am Ben Grumbles, Deputy Assistant Administrator for Water at the
U.S. Environmental Protection Agency (EPA). First, let me convey Tracy Mehan’s
regrets for being unable to be here today to speak with this Subcommittee.
Second, I appreciate the opportunity to share with you EPA’s perspectives and
actions regarding the extent of Methyl Tertiary-Butyl Ether (MTBE) contamination
of our nation’s valuable water resources. EPA has been and continues to craft
national policies and programs to improve air quality while also ensuring the
provision of safe, reliable drinking water to all of our citizens.
Sources of MTBE Contamination
The nation’s fuel supply contains constituents,
including MTBE, that may pose both human health and environmental risks when not
managed carefully. MTBE, as well as other gasoline components, has the potential
to be released to the environment wherever gasoline is stored, transported, or
transferred. The most significant sources of contamination of water resources
are from leaking underground and aboveground storage tanks, pipelines, refueling
spills, emissions from older marine engines, and to a much lesser degree, storm
runoff and precipitation. However, the presence of MTBE makes the challenge of
cleaning up these releases more difficult, because MTBE’s chemical and
physical properties make it much more likely to reach ground water than other
petroleum constituents. Even at low concentrations, MTBE may make the water
undrinkable due to its unpleasant taste and odor.
MTBE’s Impact on Drinking Water Supplies
MTBE contamination from all sources, but
primarily from underground storage tanks, is fairly widespread. Approximately
419,000 petroleum releases from underground storage tanks have been reported
since the beginning of EPA’s Underground Storage Tank program in the mid-
1980's. There are also hundreds of thousands of abandoned underground storage
tanks, many of which have releases that need to be addressed. In addition, there
is emerging evidence that vapor releases from new and upgraded underground
storage tanks are common, and these vapors containing MTBE can find their way
into ground water.
A national study by the New England Interstate
Water Pollution Control Commission in 2000 found that most states detect MTBE at
60 to 80 percent of leaking underground storage tank sites. Based on an analysis
of data from 31 states, a report in Environmental Science & Technology (May
2000) estimated that up to 9,000 community water supplies in those 31 states may
be threatened by MTBE contamination. However, the U. S. Geological Survey (USGS)
and others have reviewed the data underlying this study, and more recent
surveys, and have estimated that the number of threatened community water
supplies is likely far lower.
MTBE contamination has affected communities
across the country. For example, the City of Santa Monica, California has faced
the loss of a significant portion of its drinking water supplies due to MTBE
contamination caused by failures of underground storage tank systems. Lake Tahoe
has faced similar problems. In Long Island, New York, MTBE contamination has
resulted in alternate or improved water supplies having to be provided for over
160 affected public and private wells. Pascoag, Rhode Island, while smaller in
size than Santa Monica, Lake Tahoe or Long Island, has also lost its drinking
water supply. More recently, attention has turned to a release in Roselawn,
Indiana.
To gauge the impacts of MTBE levels in our water
supplies, let me give you some background on the Agency’s Drinking Water
Advisory for MTBE, published in 1997. The advisory provides information and
guidance to people and agencies concerned with potential taste and odor impacts
on consumers from the presence of low levels of MTBE in their drinking water.
The advisory is not a legally enforceable standard. The 1997 advisory recommends
not exceeding MTBE levels of 20-40 parts per billion (ppb) to avoid unacceptable
taste and odor.
To assess the extent of MTBE contamination at the
national level, EPA is collecting data on MTBE in finished drinking water as
part of the Unregulated Contaminant Monitoring Rule, which was published in
1999, to cover new monitoring that began in 2001 . This rule requires all large
public water systems and a nationally representative subset of small systems to
monitor for and report results of MTBE sampling. Preliminary data indicates that
MTBE has been detected in only 1 of the 154 large systems that have reported to
date, at a level of 13 ppb. Of the 283 small systems that have reported, 3
systems detected MTBE at levels ranging from 6 - 49 ppb. The complete set of EPA’s
unregulated contaminant monitoring occurrence data will be available in 2004.
The USGS has amassed a large data set for the
period 1993-2000 through its National Ambient Water Quality Assessment. Their
data show that, as you might expect, MTBE occurs more frequently in water
supplies in regions with high MTBE use, but that the vast majority of detections
are very low levels, with a median concentration of 0.5 ppb. In addition,
results published in 2001 from a joint USGS/EPA study of 12 northeastern states
for the period 1993-1998 showed that MTBE was detected in 7.8 percent of
community drinking water supplies, with less than 1 percent of these detections
above the 20 - 40 ppb levels cited in EPA’s Drinking Water Advisory. Again,
this 12-state study also concluded that MTBE is detected five times more
frequently in drinking water from public water systems in areas requiring
reformulated gas or winter oxygenated fuel than in areas where non-reformulated
gas or winter oxygenated fuel are not required.
Another concern is the potential risk to
private household wells, which EPA does not have the statutory authority to
regulate. In 1998, the State of Maine reported on sampling conducted on 951
household drinking water wells and 793 public water supplies. In this study,
MTBE was detected in 16 percent of the sampled household wells, with 1 percent
of these wells containing MTBE levels exceeding the EPA Drinking Water Advisory
level. The public water systems also reported detection frequency of 16 percent,
but none of the systems showed levels above the upper end of EPA’s Drinking
Water Advisory.
Addressing the challenges
Public health researchers have limited data about
what the adverse health effects may be if a person ingests water contaminated
with MTBE. EPA has been working aggressively to conduct or support studies to
better quantify the risk from ingesting water containing MTBE.
In March 1998, EPA added MTBE to its Drinking
Water Contaminant Candidate List, which is the Agency’s targeting and
prioritization tool to make risk-based decisions on contaminants the Agency will
consider for future regulatory action. EPA is committed to making a decision at
the earliest possible time as to whether or not a health-based regulation for
MTBE is appropriate.
This decision, like others involving the
protection of public health, should be based on sound scientific information. In
the case of MTBE, we are currently conducting an assessment of the human health
consequences due to ingestion of water containing low levels of MTBE. We plan to
issue a final health assessment in spring 2003. This assessment, coupled with a
much clearer picture of the levels and extent of MTBE contamination across the
U.S. from data collected through EPA’s unregulated contaminant monitoring
program data and USGS’s studies, will provide the solid scientific
underpinning for making the right public health decision.
EPA is taking several actions to aid states and
localities in addressing MTBE contamination. EPA has provided substantial
funding and/or technical support to Santa Monica, South Lake Tahoe, Long Island,
and Pascoag, Rhode Island to remediate MTBE. In addition, EPA is chairing a
federal-state workgroup that will create interim guidance for states on the
assessment and remediation of MTBE contaminated sites. EPA also maintains a
comprehensive website covering the full depth and breadth of MTBE issues. EPA is
also conducting a demonstration of treatment and remediation technologies for
MTBE-contaminated soil, ground water and drinking water at Port Hueneme,
California.
Closing Thoughts
Thank you, Mr. Chairman, for the opportunity to
testify today before this Subcommittee on this important subject. EPA looks
forward to working with you on this and other issues relevant to protecting the
quality of one of our nation’s most precious and critical resources. That
concludes my prepared remarks, and I would be happy to answer any questions.
|
|
