If you are a journalist wanting to take advantage of EPA databases to report on local (or even national) environmental conditions, EPA is offering a big-box store of goodies. It's called EPA Data Finder.
It's a step beyond the all-in-one EPA data interfaces many journalists are used to (such as Envirofacts  or ECHO ), in that it catalogs some of the less-known specialized databases. It is unusual among government data programs in that it explicitly encourages third-party developers to build apps based on open agency data.
The home page for EPA Data Finder is here.  It is organized by topics and media (air, water, etc.). It links to an EPA-hosted "Data and Developer Forum."  It also has a very useful catalog of "other environmental data finders"  at other federal agencies.
EPA also encourages third-party developers through its "Developer Central" page.  This is not a pipe dream — since many apps have already been developed to use EPA data. You can find a catalog of available apps, often free, for your smartphone or desktop at EPA's "My Green Apps" page.