The stream has been hidden for years, buried under the streets of Southwest Baltimore's poorest neighborhoods, almost forgotten.
Only when it rains does the stream come alive, an underground current that carries with it the litter of storm drains - plastic bags, soda cans and other trash. It emerges near the Carroll Park golf course, disgorging into a rocky bed of the Gwynns Falls that holds a fetid cocktail of sewage and garbage.
Far more dangerous is the pollution that the naked eye can't see - nitrogen, zinc and lead from automobile exhaust, among other sources. The chemicals accumulate on roads and sidewalks and are washed into waterways when it rains.
In a common stream, vegetation would slow that down and microorganisms in the water would feed on the pollutants. But a buried stream - one paved over or filled in with dirt to accommodate development - has no such life forces. It is a direct chute from the city streets to the falls and then to the Patapsco River and, eventually, the Chesapeake Bay.
"These streams are just ecosystems waiting for water," said Sujay Kaushal, an ecologist with the University of Maryland's Center for Environmental Science. "What's happening to them is like emphysema. If you compromise the smallest capillaries, then the patient can't breathe."
Kaushal spends much of his time searching for buried streams in hopes of persuading state and local governments to restore some of them. To help him, he has enlisted Andrew Elmore, a landscape ecologist from the center's lab in Frostburg. Elmore uses advanced mapping techniques to locate the streams, then computer modeling to determine how many have been silted over.
Together, they have found hundreds of buried streams in the Gunpowder and Patapsco watersheds alone, and they believe that more exist in Howard, Anne Arundel, Carroll and Harford counties. Bringing streams back involves removing the concrete or dirt that covers them, remaking the stream bed and planting vegetation to keep the soil in place. So far, just a handful of streams has been restored.
The practice of burying streams began more than a century ago.
Baltimore's builders wanted to direct water away from people's homes - both to prevent flooding and because, in the days before modern sewage and storm drains, being too close to the flow was a health hazard. Because Baltimore is part of the Chesapeake Bay's drainage area, thousands of tiny guts and gullies fill with water during heavy rain. But when it's dry, they don't look like streams. So, one by one, developers filled them in.
