What does “The city (Ferguson) learned too late that the well was dry” mean?

I scratched my head in understanding the meaning of the following passage in the article titled, “The tragedy of Ferguson” of Time magazine (September 1 issue). [Some excerpts appear at mediabistro.com, and a teaser at time.com.]

“Ferguson is no longer just the name of a township. It has become a stern lesson in the value of public trust - the city learned too late that the well was dry – and a painfully familiar one. When the shots rang out on Aug 9, the usual figures assumed the customary positions. Al Sharpton? Check. Cable-news anchors? Check. Activist in Guy Fawkes masks? Check."

What does “the well was dry” mean? What does "well" account for? Additionally, What does “Check” mean? Does it mean “Yes / Possible”?

"The well ran dry" is a metaphor that means you have run out of something, originating from the idea that a well, where people bring up water from, can run out of water, i.e. run dry.

Saying "the well was dry" in your excerpt is indicating that the well of public trust has run dry. So, the public no longer trusts the officials who run the city.

"Check" is a noun, a verbal representation of the mark that would be made against a list. The writer is going through a list of "the usual figures" who "assumed the customary positions" and confirming their existence and that they're acting as they have before.

Thanks to jwpat97 and Robusto for the corrections.

I think that the well is dry refers to the idiom:

You never miss the water till the well runs dry. ( fromTFD)

• Prov. People are not grateful for what they have until they lose it. Jill: I never realized what a good friend Jeanie was until she moved away. Jane: You never miss the water till the well runs dry.

• Here it refers to the value of public trust that the city has lost with its citizens.

'Check' refers to a sort of 'routine control' of the presence of the figures active in the place since the riots started.

"The well running dry" idiom means that you have used up all of a limited resource. It carries an implication that the resource was squandered; not used carefully. In this case, the limited resource is the trust the public had in the Ferguson city officials.

In terms of the "check", it is more a poetic structure than a structure of prose. The idea is to simulate the idea of a check list where the items are "Al Sharpton", "Cable News Anchors" and the "Guy Fawkes guys". It is meant to make you imagine a list of these guys with a big check mark next to them.

The implication is that this is a situation that happens, in one form or another, over and over again. The check list is implied to be a standard template that is applied in many situations, and by checking off the items in the list we see that this particular situation follows a common template seen over and over again.