Each agency has certain emergency preparedness programs for various programs. I doubt the EPA needs the guns to enforce EPA regulations, more like for a SHTF plan where they get vacuumed up into a big ball of armed Feds.
But as such, they’ll still shoot you if they think they can get away with it.
http://web2.utc.edu/~John-Tucker/Courses/esc430/esc430mat/darter/tellico.html
You got to wonder, with all these fed alphabet agencies getting tooled up, however ridiculous it is considering their charter. Obozo would be one to consider such a thing, considering his rhetoric.
Could there be some overall plan to quickly integrate this mess?
Considering how inept the BATF is, the rest like the EPA, IRS, DOE, etc. ought to make for a target rich environment.