Best Management Practices (BMPs) are a method by which the adverse impacts of development and redevelopment are controlled through their application. BMPs are defined in the state's draft Storm Water Manual "as schedules of activities, prohibitions of practices, maintenance procedures, and structural and/or managerial practices, that when used singly or in combination, prevent or reduce the release of pollutants to waters of Washington State." The types of BMP identified by the state are source control, runoff treatment, and flow control.
The primary purpose of using BMPs is to protect beneficial uses of water resources through the reduction of pollutant loads and concentrations, and through reduction of discharges (volumetric flow rates) causing stream channel erosion.
It is generally more cost effective to prevent impacts using source control than using runoff treatment to remove pollutants. However, since source controls cannot prevent all impacts, some combination of measures will always be needed.
Collaborative Research: Streamflow, Urban Riparian Zones, BMPs, and Impervious Surfaces
The U.S. EPA Landscape Ecology Branch (LEB) in Research Triangle Park, North Carolina is currently conducting collaborative landscape/stream ecology research in the Clarksburg Special Protection Area (CSPA) in Montgomery County, Maryland. The CSPA is an area of rapid development that we expect will be built out within the next five to ten years. The Montgomery County Department of Environmental Protection (DEP) has been monitoring stream biology and chemistry in the area streams for a decade and the CSPA involves the use of best management practices (BMPs) that are designed to limit the impact of development on water resources. The objective of the LEB research is to correlate the impacts of ongoing development and the mitigating effect of local BMPs on the hydrological, biological, and chemical parameters of the CSPA water resources using a Before-After, Control-Impact (BACI) study design. The project is focused on determining the effectiveness of BMP mitigation on streamflow disturbance, channel erosion and stream sedimentation due to impervious surfaces, sub-surface storm sewers and altered landform due to urbanization.
Our primary research goal is to map development and BMP placement as they occur; both the anthropogenic surface structures such as roads, buildings, parking lots, and changes in surface topography associated with urbanization and the subsurface storm sewer network; and to monitor the physical, chemical, and biological aspects of the associated water resources as that development happens. Changes in streamflow, surface water/groundwater relationships, and the biological and chemical parameters of the CSPA water resources will be correlated with development patterns, anthropogenic alterations of the environment, and the BMPs designed to mitigate the impacts of development. We have obtained four Light Detection And Ranging (LiDAR) overflights of the study area (Figure 2) that greatly increase the spatial resolution of the topographical analyses possible in the CSPA. These overflights and future LiDAR and other remote sensing (RS) collections will be used to determine if RS technology can be used to map changes in stream morphology associated with development as well as to assist in the hydrological modeling and surface mapping of that development. Our research is intended to assess the effectiveness of BMPs by employing both positive and negative controls (stream gauges and monitoring in areas without development and areas developed without the CSPA BMPs) as well as pre- and post development data from areas gauged prior to development within the CSPA (Figure 3).
This research involves two primary components:
1) High resolution watershed mapping over time - topography (LiDAR), aerial photography, satellite imagery, GIS, BMP placement and development mapping and
2) Coordinated monitoring of physical and biological parameters: chemical and biological stream monitoring, streamflow and precipitation gauging, and weather parameters.
To date, the USEPA has:
a) Funded the United States Geological Survey Water Resources Discipline (USGS WRD) for the placement of five stream gauges and a precipitation gauge in the CSPA to complement the existing Montgomery County DEP precipitation gauge,
b) Collected repeat LiDAR data for analysis of stream channel and landform change (Figure 2), and
c) Collected multiple high-resolution satellite data for mapping land-cover change due to development.
This EPA-USGS-DEP collaborative research is an example of a Federal-Local technology-transfer partnership where innovative technologies are researched at the Federal level and the results made available at a local level for neighborhood solutions. This research effort is an example of former EPA Administrator Mike Leavitt's "Enlibra Principles" , where the "principles of flexibility, innovation, partnership and collaboration ... and other common sense ideas that will accelerate environmental progress" guide the research effort. This research is a collaborative effort where local stakeholders are involved setting research goals and Federal agencies are involved offering expertise and capabilities not available at the local level. Partners in this research are EPA Landscape Ecology Branch, Research Triangle Park, North Carolina; Montgomery County Department of Environmental Protection (DEP), Rockville, Maryland; USGS Water Resources Discipline (WRD), Baltimore, Maryland and Eastern Geographic Science Center (EGSC), Reston, Virginia; University of Maryland, Baltimore County, Maryland (UMBC), Department of Geography and Environmental Systems, and The Center for Urban Environmental Research and Education (CUERE); University of Maryland, College Park, Maryland, Department of Civil & Environmental Engineering and the Behavior, Ecology, Evolution and Systematics (BEES) Program; College of Engineering, Virginia Polytechnic Institute and State University, Blacksburg Virginia; Environmental Systems Analysis, Inc., Annapolis Maryland; and the Maryland-National Capital Park and Planning Commission (M-NCPPC), Silver Spring Maryland.
Jerry M. Nahas & Associates (JMNA)
4015 Crown Point Drive, Unit 308
San Diego, CA 92109
Phone: (858) 352-6879