This article from Orion looks at an "urban wilderness" in Brooklyn that is being reclaimed and reused by locals.
"Ridgewood Reservoir is a curious new kind of landscape. This is not a park, or a piece of preserved nature, but a previously developed area in the process of reverting to wildness. Urban wildernesses tend to happen by mistake. In a city like New York, where space is at such a premium that former synagogues, sugar factories, and schools have all been reborn as luxury condos, a wilderness can only be the result of inattention."
"Ridgewood Reservoir is the recipient of such benign neglect. Originally built to store water from wells and ponds on Long Island for Brooklyn, the three-basin, 100-million-gallon reservoir came under the control of New York City's Board of Water Supply when the five boroughs united in 1898. It continued to provide Long Island water to Brooklyn throughout the early twentieth century, but development on Long Island was compromising water sources, and fast-growing New York was already looking elsewhere to slake its thirst. The Croton Water System, delivering water from upstate Westchester and Putnam counties, was completed in 1911; the Catskill System was finished in 1927; and the last of the Delaware System's four massive reservoirs, capable of supplying half the current demand, came online in 1965. The first Catskill water-the 'champagne of drinking waters'- came to Brooklyn in 1917, and from then on, as upstate aqueducts and tunnels came into service, Ridgewood Reservoir gradually became obsolete. By 1960, it was demoted to backup, and in 1989, the city decommissioned it and drained two of its three basins. It sat forgotten-by humans anyway-until 2004, when it was signed over to the Department of Parks and Recreation. And that's when things got interesting."