A government document is a document published by some part of a state government or the federal government. Examples of government documents include Senate bills, reports published by government agencies like the FDA or EPA, and so on. There are many government documents. Government documents are a good source of statistics and research.
In general, recent government publications are freely available online. There are a two easy ways to find these. Each is outlined below.
The usa.gov website is a search engine for US government websites. When you search with it, you search only government websites.
Google using advance searched techniques
You can use Google to find government documents if you use a few advanced features. Google allows you to limit your search to certain websites and to certain files.
To begin with, you can limit your searches to .gov sites (government sites) by adding site:.gov to your search. If you wanted to search for government websites about water quality you could type water quality site:.gov. If you want to search just a single website, you can do that too, e.g., water quality site:epa.gov
You can also use Google's advanced features to find PDFs on these sites, rather than just plain webpages. It can be good to limit your searches to PDFs because PDFs are how finished reports are often stored. You can use filetype:pdf to limit your search to PDFs.
So, to find PDFs on the epa.gov site, your search might look like this: water quality site:epa.gov filetype:pdf. (Screenshot below.)