On Friday in Detroit, hundreds of local residents and activists — and, somewhat inexplicably, Mark Ruffalo — gathered to protest what has become an only-in-Detroit kind of crisis: The city's water utility has been shutting off service to thousands of homes, many with the elderly, the poor and children inside.

The story of how this has happened — and on the shores of one of the largest bodies of freshwater in the world — is not as simple as one of government incompetence or indifference to the poor.

The Detroit Water and Sewerage Department says that nearly half of its customers haven't been paying their water bills, for a total of about 90,000 delinquent accounts, leaving the public utility with some $90 million in debt. But in a city of abandoned properties, squatters and tremendous poverty — 38 percent of Detroit lives below the poverty line — the department has had a hard time distinguishing empty homes from occupied ones, and customers who legitimately can't afford to pay from those who've simply opted not to.

As the Detroit Free Press editorialized, the utility has long tolerated unpaid bills, creating a "culture of nonpayment." Last year, however, under the city's new emergency management, the department began an aggressive campaign to shut off water to unpaid accounts, and the effort has ramped up in the last three months. In May, the department says it sent shutoff notices to 46,000 accounts. But officials point out that many more customers respond to these letters by immediately paying their bills, or setting up payment plans, than by having their water cut off.

This suggests, the department argues, that plenty of residents can afford to pay — they've just chosen not to. And, as a result, water rates have risen for customers who pay responsibly to help cover the costs of their neighbors who do not.

The department's strategy has been to cast a sweeping net for accounts more than $150 overdue, hoping that the truly poor caught in the crackdown will be funneled into payment plans or charitable programs. But many grave cases — the elderly unable to bathe, children living in homes without running water — have not surprisingly arisen. As have some notable other cases: Facilities used by the Red Wings and the Detroit Lions have apparently been behind on their water bills, too.

As the shutoffs have escalated, Rep. John Conyers (D-Mich.), who attended Friday's rally, has called the campaign "inhumane." The national nurses group that organized Friday's event has warned that the lack of clean water creates a public health threat. Even the United Nations has weighed in, at the urging of local activists, suggesting that the city risks violating the human right to water by shutting off access to those who can't afford it. All of these fears are also bound up in the deep worry that the city is trying to improve the department's finances at the expense of poor residents so that it can privatize the water system.

By mid-summer, the crisis has come to represent many competing but not necessarily inconsistent lessons about Detroit. The shutoffs are a sign of the city's long-running financial mismanagement. They're a sign of the city's painful efforts to govern itself responsibly again. They're a sign of double standards and terrible choices, of costs borne differently by corporate debtors and local residents. They're a sign of the apathy (and culpability) of Detroiters who'd shirk their fair share, but also of the tragedy of others whose standard of living in a U.S. city looks out of the Third World.

The hardest part may be acknowledging that all of these things are true at the same time.

UPDATE: The Detroit Water and Sewerage Department has announced that it is stopping water shutoffs through at least the end of July, giving residents who legitimately can't afford to pay a grace period to prove that to the department. Read more from the Detroit Free Press here.

Some more images from last Friday Friday: