Urbanization Summer Heat Impact on Stream Ecosystem in the City of Baltimore

Urbanization summer heat often results in increased stream temperatures due to a large amount of impervious area, removal of vegetation and replacement of precious areas with impervious surfaces which results in changes in the characteristics of the surface hydrograph increasing, stormwater runoff volumes and increased the temperature in the streams. The physical aspect of an urban stream restoration can be readily accomplished, the biological aspects of the restoration may be slower to rebound due the amount of impervious area within the watershed. The warm runoff will have a negative impact on the biological aspects within the stream valley and ecosystem of the stream. To reduce the temperature and improve the biological aspect of urban streams within the watershed, an additional stormwater best management practices (BMPs), daylighting streams or providing wetlands that may allow the runoff to infiltrate or cool prior to entering into the stream. This paper presents urban stream restoration projects that have improved water quality, aquatic ecosystem and protected the existing utility infrastructure to meet National Pollution Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) permit under the federal Clean Water Act requirements. Using natural stream restoration approach by removing the concrete channel, daylighting stormwater pipe, reconnecting the floodplain, use of boulder types of structures to stabilize the stream banks and reduce the energy of the stream system. This natural stream restoration design would provide a stable stream system supporting a biologically diverse aquatic and riparian ecosystem, as well as provide a beautiful amenity to the communities. In addition, the stream restoration projects would provide the nitrogen, phosphorus, and sediment reduction into the nearest watershed and meet the Chesapeake Bay Total Maximum Daily Load goal.