Liz Barry just posted this great overview of recent Brooklyn maps on the PBS Mediashift IdeaLab blog:

"With Public Lab, a Camera Flies in Brooklyn to Monitor Pollution"

http://www.pbs.org/idealab/2011/10/with-public-lab-a-camera-flies-in-brooklyn-to-monitor-pollution273.html

In the worst-polluted spots, 4.5 percent by weight of the sediments at the bottom of Brooklyn's Gowanus Canal are polyaromatic hydrocarbons (PAH), oily residues from manufactured gas works and oil refineries. Many other heavy industries, including coal yards, cement makers, soap makers, tanneries, paint and ink factories, machine shops, and chemical plants, left a wide range of other toxic chemicals. The former tidal inlet surrounded by wetlands was bulkheaded in the 1860s, resulting in dead-end channels so stagnant a massive tunnel was engineered to move water from the East river underneath downtown Brooklyn to "flush" the toxic waters out to the harbor.

Clearly, the official surveys indicate a lack of environmental information here. Using Public Laboratory tools and methods, grassroots investigators have documented not only active pipes missed in the official survey but also flows where no pipes are visible. Georeferenced aerial imagery stitched in January of this year by the Gowanus Arctic Explorers captured evidence of additional unknown flows melting the ice next to a filled-in basin where Vechte's Brook and its original spring are buried -- or perhaps it is merely evidence of illegal industrial dumping of liquids with a lower freezing point than water.