Search using your preferred keywords, then select the "UNI Documents" or "UNI Documents Microfiche" filter option (under "Location") to limit your results to government documents. Note: These are physical items in the library on the first floor (one floor below the library's main floor). Need help? Stop at the library services desk on the second floor (where you check books out) and ask!
HathiTrust has a wealth of digitized government publications and more. Use the "Author" filter to limit to government agencies, congress, etc. Also consider using the "Date of Publication" filter to narrow your results.
"GovInfo is free U.S. Government information for all. GovInfo is a service of the United States Government Publishing Office (GPO), which is a Federal agency in the legislative branch. GovInfo provides free public access to official publications from all three branches of the Federal Government."