This is an interesting article, thanks for sharing. Your summary does not quite reflect the article though. You say "In fact, it's been known for months that the DEA receives intercepts from the NSA in such volume that they have an office devoted to handling them (the DEA's "Special Operations Division")", which to me created the impression that the NSA was funneling large amounts of information about US citizens to the DEA.

However, the article actually says: "...two dozen arms of the government working with the Special Operations Division, including the Federal Bureau of Investigation, the National Security Agency and the Central Intelligence Agency.", and later that "the Special Operations Division of the DEA funnels information from overseas NSA intercepts, domestic wiretaps, informants and a large DEA database of telephone records to authorities nationwide to help them launch criminal investigations of Americans. The DEA phone database is distinct from a NSA database disclosed by former NSA contractor Edward Snowden." [emphasis mine]

It's quite possible that the NSA passed only occasional information about non-US citizens - it's impossible to tell from that article - if that's the case, then to many people they're acting within their mandate.

I'm not trying to defend the NSA, and I'm deeply troubled by the implications of mass surveillance. But it's important I think to be clear about the claims we're making since otherwise it's easy for people to dismiss us.