Like any sources used by journalists, there are many ways to assess the quality of content of an information source.
Journalists usually confirm information they plan to use with several independent sources, in fact.
This is especially true when important information is involved. Government sites are generally credible and information can be used from them with proper attribution. However, remember that this is the government s point of view. Educational sites will vary wildly in quality of information. Be careful, especially with student home pages.