Methyl Tertiary Butyl Ether (MTBE)

Clean Air Act rules governing fuels and fuel additives are found in 40 CFR 80.

The 1990 Clean Air Act Amendments required nine metropolitan areas that had the most severe ozone pollution to use, year-round, reformulated gasoline containing fuel oxygenates. Numerous additional metropolitan areas also chose to participate in the oxygenated fuels and reformulated gasoline programs. In 2005, Congress passed the Energy Policy Act, which removed the oxygenate requirement for reformulated gasoline (RFG). At the same time, Congress also instituted a renewable fuel standard. In response, refiners made a wholesale switch, removing MTBE and blending fuel with ethanol (EPA 2013). In a survey published in 2006 by the New England Interstate Water Pollution Control Commission, 41 states said their state had either action levels, cleanup levels, or drinking water standards for MTBE.

In December 1997, EPA's Office of Water released a non-regulatory advisory for MTBE in drinking water. The EPA advisory is not a mandatory standard for action and is not federally enforceable, but provides guidance for communities that may be exposed to drinking water contaminated with MTBE. According to the advisory, keeping MTBE concentrations in the range of 20 to 40 µg/L or below would likely avert unpleasant taste and odor effects, recognizing that some people can detect the chemical below this concentration range. As of 2014, this advisory has not been updated and no maximum contaminant level has been established. MTBE is governed by the reporting requirements of the Title III of the Superfund Amendments and Reauthorization Act of 1986. The reports are compiled into a toxics release inventory (example). The reporting requirements are only for specific industry categories where the entity manufactures or processes more than 25,000 lbs. of a Toxics Release Iinventory-listed chemical or otherwise uses more than 10,000 lbs. of a listed chemical in a given year. Retail gasoline stations would not be covered.

MTBE is not regulated under the Resource Conservation and Recovery Act.

Visit EPA's archived MTBE Policy Documents page for additional information (Note that EPA is is no longer maintaining this website). Many states have a Web page for MTBE; a sampling of them is provided below.

Federal

MTBE in Gasoline: Clean Air and Drinking Water Issues
James E. McCarthy and Mary Tiemann.
Congressional Research Service, CRS Report for Congress, 29 pp, 2006.
Contact: National Council for Science & the Environment, info@NCSEonline.org

Achieving Clean Air and Clean Water: The Report of the Blue Ribbon Panel on Oxygenates in Gasoline
U.S. EPA, Office of Air and Radiation.
EPA 420-R-99-021, 119 pp, 1999.

Blue Ribbon Panel Findings on MTBE: Hearing before the Subcommittee on Clean Air, Wetlands, Private Property, and Nuclear Safety of the Committee on Environment and Public Works
United States Senate, One Hundred Sixth Congress, first session, October 5, 1999. 181 pp, 2000.

A Drinking Water Standard for MTBE? The Ifs and Whens of Establishing an MCL
Rachel Sakata, U.S. EPA Office of Ground Water and Drinking Water.
LUSTLine, Bulletin 33, p 6, 1999.

Monitored Natural Attenuation of MTBE as a Risk Management Option at Leaking Underground Storage Tank Sites
J.T. Wilson, P.M. Kaiser, and C. Adair, U.S. EPA, National Risk Management Research Laboratory, Ada, OK. EPA 600-R-04-179, 89 pp, Jan 2005

This report reviews the current state of knowledge on the transport and fate of MTBE in ground water, with emphasis on the natural processes that can be used to manage the risk associated with MTBE in ground water or that contribute to natural attenuation of MTBE as a remedy. It provides recommendations on the site characterization data necessary to manage risk or to evaluate monitored natural attenuation (MNA) of MTBE, and it illustrates procedures that can be used to work up data to evaluate risk or assess MNA at a specific site. The information is intended to allow state regulators to determine whether they have adequate information to evaluate MNA of fuel oxygenates at a site and to allow the regulators to separate sites where MNA of fuel oxygenates may be an appropriate risk management alternative from sites where MNA is not appropriate.

Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage Tank Sites
U.S. EPA, Office of Solid Waste and Emergency Response.
OSWER Directive 9200.4-17P, 41 pp, 1999.
Contact: Hal White, white.hal@epa.gov

State

Methyl-Tertiary Butyl Ether (MTBE) Remediation
Indiana Department of Environmental Management, 3pp, 2005.

NDEP Oxygenated Fuel Corrective Action Guidance
Nevada Division of Environmental Protection, 28 pp, 1998.

Remediation Guidelines for Petroleum Contaminated Sites in Maine
Maine Department of Environmental Protection, 2009.

State MTBE Webpages

Florida
Indiana
Maryland

• Facts About: Methyl Tertiary-Butyl Ether (MTBE)
• Methyl Tertiary Butyl Ether (MTBE) and Clean Gasoline Alternatives

Missouri
Montana
New Jersey
Oregon

Supplemental Guidance for Prioritization of Investigation and Cleanup of Underground Storage Tank Releases Containing MtBE
California Regional Water Quality Control Board, Santa Ana Region, 9 pp, 2001.
Contact: Kenneth Williams, 909-782-4496

Other Countries

Guidance for the Assessment, Remediation and Management of MTBE
Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Newcastle, Australia. CRC CARE Technical Report no. 36, 72 pp, 2016

MTBE-specific information for the assessment, remediation, and management of potentially contaminated sites in Australia has been drawn from international guidance. This guide addresses an odor-based screening level in water, ecological screening levels, and contaminant-specific considerations for site investigations and development of the conceptual site model. See Report 36 in the list of CRC CARE technical reports.