Image: Maryland Department of Natural Resources

During a recent community-level fishery survey, Pennsylvania Fish and Boat Commission biologists encountered an American shad nearly 37 miles upriver in the Schuylkill, marking the first time that shad has been spotted above Norristown since 1820. That year, the Fairmount Dam was constructed, prohibiting shad—which are native to the Schuylkill and its tributaries—from ascending the river during their annual spring spawning run. Restoring the shad population in Pennsylvania's rivers is what led to the formation of the PA Fish and Boat Commission in 1866, and the agency has since worked to remove dams that block shad and other fish from migrating. A total of 10 dams in the Schuylkill have either been removed or now have fishways that allow fish to pass through; many of these restoration projects were completed in the last five years.

Image: PA Fish and Boat Commission

While the shad sighting just below Black Rock Dam (see map above) is a measure of success for the fishways, PWD biologist Lance Butler also notes that "the resurgence of shad is an indicator or returning ecology to Schuylkill." Shad populations decimated by pollution in the early 20th century began making a comeback in the Schuylkill in the 1980s, returning the "founding fish" (a whopper of a fish tale claims American shad from the Schuylkill River saved George Washington and his troops from starvation during the Revolutionary War) to its native waters.

Though the April-June shad migration is now over, see what other species you can spot ascending the Fairmount Dam's fish ladder via the Fish Cam.

Amid all the excitement over Philly's first green roof bus shelter two weeks ago, we buried some really big news that happened the same day: Mayor Michael Nutter released the 2011 Greenworks Philadelphia Progress Report. The second annual update on the status of Greenworks—the mayor's 2009 sustainability plan that aims to transform Philadelphia into America's greenest city by 2015—can be downloaded here. Of the 151 initiatives outlined in the plan, 135 of them (89%) have been started or completed.

After the jump, a quick list of progress-report highlights from the Philadelphia Recovery Office. But the entire document is recommended reading for anyone interested in the city's future and the economic and social benefits of urban sustainability.

When the Philadelphia Water Department's aquatic biologists investigate Philadelphia's streams and rivers to take stock of the number and variety of species inhabiting our waterways (they call this process a bioassessment), they pay special attention to mayflies. The presence of pollution-sensitive mayflies can indicate the level of biological health in a stream, and a mayfly census of sorts is just one of many tools used to monitor the quality of local stream ecosystems.

About 364 days of the year, you're not likely to encounter the version of the mayfly pictured above (which is of the order Ephemeroptera and the family Baetidae). The adult, winged mayfly lives only long enough to reproduce, surviving anywhere from 30 minutes to a day, during which time its digestive system is filled with air. More often you'll see mayflies in the nymph, or naiad, stage, during which they are wingless and mostly feed on algae. And despite its name, mayflies are common not only in May but also through June, July and August.