THE BRONX - A new wetlands project has popped up right underneath the Major Deegan Expressway.

The "pop-up wetland" is a pilot program aimed at capturing stormwater runoff from the elevated highway and naturally preventing further pollution of the Harlem River.

Rainwater from the road, which experts say is filled with pollution from traveling cars, travels down tubes and into the wetland.

The U.S. Geological Survey is monitoring the water during the yearlong experiment, while the group Sustainable South Bronx is in charge of its maintenance.