PWD's Watersheds blog closes out the year with a list of 11 green missions accomplished in 2011, from innovative stormwater management projects and stream restorations to groundbreaking policy agreements and energy-generating solar arrays.

In June, the city's first porous street debuted in South Philadelphia. The 800 block of Percy Street is just six feet wide, but the replacement of traditional impervious asphalt with a porous surface has already had a big impact: During Hurricane Irene, monitoring at Percy Street indicated that stormwater runoff infiltrated into the ground instead of flowing into the sewer system. Keeping stormwater out of Philadelphia's combined sewers reduces overflows of sewage and stormwater into our rivers and streams and protects our drinking-water supply.