Suburban Land Use, Stormwater Best Management Practices, and Receiving Stream Health Assessing Implementation of Management Practices and Their Relation to Water Quality Dianna Hogan 1 , Taylor Jarnagin 2 , Keith VanNess 3 , Jennifer St.John 3 , and Rachel Gauza 3 1 USGS Eastern Geographic Science Center 2 EPA Landscape Ecology Branch, Environmental Sciences Division 3 Montgomery County Department of Environmental Protection March 25, 2009
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Suburban Land Use, Stormwater Best Management Practices, and Receiving Stream Health
Assessing Implementation of Management Practices and Their Relation to Water Quality. Presentation by Dianna Hogan, Taylor Jarnagin, Keith VanNess, Jennifer St.John, and Rachel Gauza, March 25, 2009
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Suburban Land Use,
Stormwater Best Management Practices,
and Receiving Stream Health
Assessing Implementation of Management Practices
and Their Relation to Water Quality
Dianna Hogan1, Taylor Jarnagin2, Keith VanNess3, Jennifer St.John3, and Rachel Gauza3
Designed to lessen impacts of suburban land use by treating
and/or retaining or detaining stormwater runoff
recharge trenchfiltration
detention basin
Splitter with vent
Clarksburg Special Protection Area (CSPA)
Partnership
Montgomery County Department of Environmental Protection (DEP)
Montgomery County Department of Permitting Services (DPS)
Maryland-National Capital Park and Planning Commission
University of Maryland College Park (UMDCP)
Virginia Polytechnic Institute and State University
USEPA Landscape Ecology Branch, Ecosystems Research Division, and Office of Water
US Geological Survey (USGS) Eastern Geographic Science Center (EGSC) and Water Resources Discipline (WRD)
Clarksburg Special Protection Area (CSPA)
Partnership Goals
Study the impacts of land use change
Agriculture / forest to suburban
Document how the changes in topography and imperviousness
affect the hydrology, biology, chemistry, and geomorphology of
receiving streams
Assess the effectiveness of local level BMP mitigation protocols
Goal: Better understand the potential pollutant retention of
specific BMP mitigation designs and promote the application of
this information across the Chesapeake Bay region
Clarksburg Special Protection Area (CSPA)
Study Site Description
Developing under SPA guidelines
Designed to protect high quality streams in developing areas
Advanced sediment and erosion controls, stormwater BMPs in series, interception of water further upstream
Before-after control study
5 subwatersheds (0.9 – 3.4 km2)
Undeveloped positive control on parkland
Developed negative control in Germantown (completely built out; pre-2000 criteria)
Three test areas
5 USGS stream gages (red dots)
Water quality (blue dots)
2 precipitation gages (near Sopers and Cabin Branch)
Clarksburg Special Protection Area (CSPA)
Methods and Preliminary Findings: BMP Database
Local level BMP database (GIS)
Pre- and post-development
Building footprints, roads
Stormwater management infrastructure and conveyance (pipes, swales, treatment trains)
BMP type, placement, DA, IC
Stormwater flow direction
Integrate land use and BMP information with chemical, biologic, and physical stream data
Study local level BMP protocols for water quality mitigation
Effect of BMP type, location, use in series or as individuals, and development patterns
Clarksburg Special Protection Area (CSPA)
Methods and Preliminary Findings: BMP Database
Inclusive
retention or infiltration areas, wet ponds, extended detention ponds, sand filters, etc.
private BMPs - dry wells along the back side of houses by streams
Temporal
Sediment and erosion control during construction (settling for large volumes of sediment-laden runoff)
Stormwater management post-construction (quantity and quality control of stormwater runoff)
Adjacent sediment trap prior
to conversion to a detention
basin Clarksburg, MD 5/06
Sand filter
Clarksburg, MD 5/06
Dry well schematic
Dry well
Clarksburg, MD 9/05
Clarksburg Special Protection Area (CSPA)
Methods and Preliminary Findings: BMP Database
Clarksburg Special Protection Area (CSPA)
Methods and Preliminary Findings: LiDAR
Four Light Detection And Ranging (LiDAR) overflights
2002, 2004, 2007, 2008
Optical remote sensing
Measures properties of scattered light to determine distance by measuring time delay between transmission and detection of the reflected signal
Map temporal changes in the landscape, stream morphology, watershed hydrology, infiltration conditions, and used for hydrological modeling Z
X
Y
After, Flood, 1997
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2002
Jarnagin 2008 EPA LEB
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2002
Jarnagin 2008 EPA LEB
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2004
Jarnagin 2008 EPA LEB
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2004
Jarnagin 2008 EPA LEB
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2006
Jarnagin 2008 EPA LEB
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2006
2005 post constr. BMP
Jarnagin 2008 EPA LEB
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2007
Jarnagin 2008 EPA LEB
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2008
Jarnagin 2009 EPA LEB
Clarksburg Maryland Special Protection Area: Tributary 104 site
USGS Stream Gauge Site2008
Jarnagin 2009 EPA LEB
Clarksburg Special Protection Area (CSPA)
Methods and Preliminary Findings: Monitoring
Monitoring of physical and biological parameters
Stream flow (USGS flow gages at each subwatershed)
Stream monitoring focusing on rapid habitat assessment, geomorphology, water temperature, sediment, and benthic macroinvertebrates
Precipitation gages (2)
Selected BMP monitoring
Integration of monitoring data with the BMP database
Preliminary findings in developing areas:
Stream conditions have declined
Flashier storm response
Altered stream geomorphology (bed aggradation during development then channel erosion postdevelopment)
Sinuosity ratio indicates channel straightening
Average Stream Conditions
(combined benthic macroinvertebrate and fish scores)
Clarksburg Special Protection Area (CSPA)
Methods and Preliminary Findings: Monitoring
Clarksburg Special Protection Area (CSPA)
Summary
Few studies have followed comparable small watersheds from pre-construction through build-out to evaluate various combinations of stormwater management mitigation
Development in the CSPA is ongoing - need to be further in the development process for trend analysis and determine if there will be recovery