“Altogether, these glaciers almost certainly represent the largest reservoir of water ice on Mars that is not in the polar caps,” said John W. Holt of the University of Texas at Austin, who is lead author of the report. “Just one of the features we examined is three times larger than the city of Los Angeles and up to one-half-mile thick. And there are many more. In addition to their scientific value, they could be a source of water to support future exploration of Mars.”
In geological terms, a few thousand cubic kilometers of water is nothing — it’s the contents of a couple middling lakes. But if one wanted to use the stuff, that’s a few quadrillion liters. Without recycling, enough to supply the current consumption of New York City for a million years or so. Gosh.
Of course if it’s exposed to martian atmosphere it all goes away in relatively short order, but still.