Last week, NASA's Earth Observatory shared a satellite photograph that showed how Hurricane Irene pushed sediment into the Hudson River: "In this true-color satellite image, pale green and tan water flows past Manhattan and mixes with the darker waters of New York Harbor and the Atlantic Ocean... Sediment plumes are prominent in Delaware Bay and along the Maryland, Virginia, and North Carolina coasts. Also, the Delaware, Hudson, and other rivers stand out as tan and brown tracings far into the interior landscape." So, @DJAstro, no need to worry! And, @jzeveloff, it does look "pukingly" brown, but it's just nature.

The city's Department of Environmental Protection confirmed to City Room that it is storm run-off. And Woods Hole oceanographer David Ralston told NASA, "The sediment flux from Irene is really massive...unusual, but not unheard of. One big event like this can move and deposit as much sediment as you might get in several years of regular flow on the Hudson."

A NASA image from last week

Earth Observatory also explains, "The color of the water generally depends on the amount and type of sediment, as the green, tan, and deep brown areas have varying degrees of suspended silt, sand, mud, leaf tannins, and other organic matter. Note, for instance, the darker brown tinting near the Passaic River in New Jersey (image left). The brightness, or reflectance, of the water is also an indication of how close to the top of the water column those sediments are moving."