In a muddy field in Middle River lies a concrete canal strewn with trash.
Clipboard in hand, Candace Croswell stood beside it recently and described how the structure will be transformed into a stream.
The concrete will soon be replaced by rocks and dirt, and the trash replaced by an array of plants. The goal is to slow the flow of water - and reduce the effect of nutrients and pollution in the river downstream and, ultimately, the Chesapeake Bay.
FOR THE RECORD - An article in Saturday's editions of The Sun misstated the location of a Baltimore County stream restoration project. The article should have stated that the county recently completed a restoration of a portion of Minebank Run behind Loch Raven High School.
The Sun regrets the errors.
"We're basically reshaping the channel - grading the sides and then putting in large rocks to keep the stream in place," said Croswell, a stream restoration manager with the Baltimore County environmental department.
The stream - which runs under Old Eastern Avenue and into Middle River - will be part of the Fields at Renaissance Park, formerly known as Tall Trees Park.
The park, which will include a baseball diamond, community center and other amenities, is scheduled to open in the spring.
About half of the $1 million project is being paid with a state grant. The work, which includes a restoration of the stream and construction of a pond, is part of a county program that has restored parts of 36 urban streams since 1990. Another 36 projects are planned.
Rainwater in rural areas is soaked up by the ground and gradually trickles into streams and other waterways. But in urban and suburban areas, the rainwater slides off solid surfaces - such as a roof or a road or a mall parking lot - and overburdens streams, causing soil erosion.
"When you have a degraded stream and the banks are eroding away, it carries a lot of sediment" into rivers and eventually the Chesapeake Bay, said David A.C. Carroll, director of the county Department of Environmental Protection and Resource Management.
The sediment can include high concentrations of nutrients that pollute the bay, he said.
The county recently completed a similar restoration of Minebank Run, a Gunpowder Falls tributary. A concrete portion of the streambed behind Dulaney Valley High School was replaced by large rocks that help to prevent soil erosion.
"The old traditional engineering approach was to put it in concrete," Carroll said. "We now know there are lot of negatives in that."
The county spends $3 million to $4 million annually restoring streams, Carroll firstname.lastname@example.org