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
1USGSEastern Geographic Science Center
2EPA Landscape Ecology Branch, Environmental Sciences Division
3Montgomery County Department of Environmental Protection
March 25, 2009

Clarksburg Special Protection Area (CSPA)
Presentation Overview
 Definition (BMP)
 Partnership and goals
 Study site description
Detention pond and
sand filter
 Selected methods and preliminary findings
 Local level BMP database that maps development, BMP type
and placement, and landscape stormwater flow direction
 Four Light Detection And Ranging (LiDAR) overflights
 Monitoring of physical and biological parameters

Which Best Management Practices (BMPs)?
 Suburban land management actions
 above/below ground retention or infiltration, wet or dry ponds,
sand/gravel filters, constructed wetlands, vegetated buffer strips,
etc.
 Designed to lessen impacts of suburban land use by treating
and/or retaining or detaining stormwater runoff
filtration
Splitter with vent
recharge trench
detention basin

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)
Dry well
Clarksburg, MD 9/05
Dry well schematic
Adjacent sediment trap prior
Sand filter
to conversion to a detention
Clarksburg, MD 5/06
basin Clarksburg, MD 5/06

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 After, Flood, 1997
reflected signal
 Map temporal changes in the
landscape, stream morphology,
watershed hydrology, infiltration
conditions, and used for
hydrological modeling Z
Y
X

Clarksburg Maryland Special Protection Area: Tributary 104 site
2002 USGS Stream Gauge Site
Jarnagin 2008 EPA LEB

Clarksburg Maryland Special Protection Area: Tributary 104 site
2002 USGS Stream Gauge Site
Jarnagin 2008 EPA LEB

Clarksburg Maryland Special Protection Area: Tributary 104 site
2004 USGS Stream Gauge Site
Jarnagin 2008 EPA LEB

Clarksburg Maryland Special Protection Area: Tributary 104 site
2004 USGS Stream Gauge Site
Jarnagin 2008 EPA LEB

Clarksburg Maryland Special Protection Area: Tributary 104 site
2006 USGS Stream Gauge Site
Jarnagin 2008 EPA LEB

Clarksburg Maryland Special Protection Area: Tributary 104 site
2005 post constr. BMP
2006 USGS Stream Gauge Site
Jarnagin 2008 EPA LEB

Clarksburg Maryland Special Protection Area: Tributary 104 site
2007 USGS Stream Gauge Site
Jarnagin 2008 EPA LEB

Clarksburg Maryland Special Protection Area: Tributary 104 site
2008 USGS Stream Gauge Site
Jarnagin 2009 EPA LEB

Clarksburg Maryland Special Protection Area: Tributary 104 site
2008 USGS Stream Gauge Site
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

Clarksburg Special Protection Area (CSPA)
Methods and Preliminary Findings: Monitoring
Average Stream Conditions
(combined benthic macroinvertebrate and fish scores)

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
 Increasing targeted monitoring efforts – USGS postdoc and discussing sediment
collection
 We will continue to evaluate the effectiveness of different BMPs and water quality
protection measures
Correlate changes in stream flow,
biological and chemical
parameters, and geomorphology
with development patterns and the
BMPs used to mitigate the impacts
of development
1998 2008

THANK YOU !
Dianna Hogan
dhogan@usgs.gov
Taylor Jarnagin
Jarnagin.Taylor@epamail.epa.gov
Keith VanNess
Keith.VanNess@montgomerycountymd.gov
Jennifer St.John
Jennifer.St.John@montgomerycountymd.gov
Rachel Gauza
Rachel.Gauza@montgomerycountymd.gov
Hogan, D., Jarnagin, T., VanNess, K., St.John, J., Gauza, R., 2009, Suburban Land
Use, Stormwater Best Management Practices, and Receiving Stream Health [abs.]:
Ecosystem Based Management - The Chesapeake and Other Systems, p. D-45.