At the Federal level, there is a fair amount of information available at no cost. Some good web sites include:
Thomas for Federal information, including pending legislation and laws
GPO Access for links to the full Federal Register and Code of Federal Regulations, as well as committee hearings, public laws, the U.S. Code (laws), administrative decisions, Commerce Business Daily, and other government information
U.S. EPA's Laws and Regulations page, which includes their Federal Register Environmental Subset, as well as links to dockets, codified regulations, and current legislation.
The National Library for the Environment, sponsored by the National Council for Science and the Environment (formerly the Committee for the National Institute for the Environment) includes links to Congressional Research Reports and the Pace University School of Law Virtual Environmental Law Law Library.
U.S. EPA maintains a list of major environmental laws with links to full-text sources on the laws & regulations section of their web site. They also maintain a more comprehensive list (without links) as part of their Introduction to Laws and Regulations.
In addition, the National Library for the Environment maintains Summaries of Environmental Laws Administered by the EPA. Each summary includes background information and plain-English discussions of the provisions of the statutes that form the legal basis for EPA's programs.
If you're not sure which of the many EPA documents your method is in, the U.S. EPA Region 1 Library has compiled an Index to EPA Test Methods. The index is organized by chemical/name. The print version is also organized by method number. The index also includes Sources of EPA Test Methods, and Links to Sources of EPA Test Methods on the Internet.
The National Environmental Methods Index, a cooperative effort of the U.S. EPA and the U.S. Geological Survey, is an excellent online source for test methods. Users can search by analyte, CAS number, or method number. Users can also browse by general method and locate test methods approved for regulatory use.
The Environmental Defense Fund's Scorecard site produces local reports by combining scientific, geographical, technical, and legal information from over 150 electronic databases. Local reports include contact information for legislators and decision makers.
Another good source is U.S. EPA's Envirofacts page. It's a single point of access for environmental data collected by the agency. EPA also offers a "search by zip code" feature on their Your Community page.