The general rule among government agencies is that we're happy to supply data (we have quite a bit), but that apps based on that data should be created by private enterprise. There are, of course, exceptions. Most exceptions are for inward-facing apps (apps for feds to use, to get our jobs done better), but there are also excellent public-facing apps.
If you're considering contracting for app creation (or crafting one yourself or with fellow Interior staff), consider the following:
There are many more considerations, but these should get you started on the path to a good decision.
Here's a quick plug for some work by a sibling agency, the EPA: Apps for the Environment: Lessons Learned. If you haven't read it yet, you should do so before committing to app development.