The Development of the Basin Condition Score BCS Methodology

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The Development of the Basin Condition Score
(BCS) Methodology

• Anne Arundel County Office of Environmental
  Cultural Resources

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Who worked on the BCS Method?

• Anne Arundel County Office of Environmental
  Cultural Resources
• Prince Georges County Department of
  Environmental Resources
• Maryland Department of Natural Resources
• Anne Arundel County Department of Public Works
• Dewberry Davis, LLC.

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Need for BCS

• DNR and data to decisions
• Many projects, little money
• Watershed wide benefits of restoration
  implementation
• Defensible method for choosing which
  subwatersheds to work in after WRAS assessment

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Overview of the BCS

• Developed during the Upper Patuxent River WRAS,
  2002-2003
• Used to evaluate conditions of subwatersheds
  assessed in the WRAS
• Multimetric approach
• Used SCA and other field data and GIS data.

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Overview of the BCS, cont.

• Indicators developed to act as surrogates for
  ecological functions to the extent feasible
• Indicator scoring ranges based upon
• Scientific research in peer review journals
• Other research or publications
• Local experience of professionals (mainly DNR)
• Best professional judgment of authors
• Self-referenced based upon field data in Upper
  Patuxent

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Overview of the BCS, cont.

• 21 indicators, 5 indicator groups
• Some indicators weighted because of their
  importance to stream health (factor of 2 or 3)
• Points from each indicator group used to derive
  the total BCS
• Groups allow for honing in on problem areas even
  where total BCS indicates low impact overall

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Overview of the BCS, cont.
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Water Quality

• Provide indication of land use impacts
• Collected during WRAS field work
• Two indicators scored
• Baseflow NO32 concentration departure
• Baseflow PO4 concentration departure

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Living Resources

• Measurements of biological conditions
• Fish and benthic macroinvertebrates measured
• Four indicators measured
• Aquatic Insect Community Condition (3)
• Anadromous Fish Utilization
• Presence/Absence of Sensitive Species Protection
  Areas
• Stream Fish Community Condition (3)

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Habitat Condition

• Primarily derived from SCA work
• For some indicators, only sites rated moderately
  severe or greater were used in scoring.
• Also from habitat assessment associated with
  biological data collection

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Habitat Condition, cont.

• Six indicators
• Channel Erosion (3)
• Pipe Outfalls
• Buffer Conditions (3)
• Fish Barriers (3)
• Overall Habitat Rating (3)
• Channel Alterations (2)

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Landscape Conditions

• Attempt to measure current and future land use /
  land cover impacts to subwatersheds
• Mostly evaluated using GIS data

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Landscape Conditions, cont.

• Seven indicators developed
• Current Imperviousness (3)
• Road Crossings
• Forest Polygon Edge/Area
• Full Build Out Increase in Impervious Cover (2)
• Percent of Subwatershed in Proposed Greenway (2)
• Percent of Subwatershed Land Area with Permanent
  Protection (2)
• Percent of Subwatershed Land Area in Agricultural
  Land Use (2)

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Hydrologic Conditions

• Attempts to describe current hydrologic
  conditions and their impacts
• Two indicators
• Flooding Potential (2)
• Stream Baseflow Condition

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BCS Application

• Nine subwatersheds
• Mix of land use and land cover
• Forest (one)
• Residential (one)
• Forest/Ag (two)
• Ag/Residential (two)
• Forest/Residential (three)

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Limitations of the BCS

• Garbage In, Garbage Out (especially with
  Landscape Indicators)
• Weak on hydrology, water quality
• First use, so not really validated
• Metrics not statistically tested for relevance
• Unknown if applicable outside the Coastal Plain
  physiographic region

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Strengths of the BCS

• Quick and fairly easy to use
• Customizable for your region
• Indicators based mostly on peer-reviewed or or
  other published literature
• Uses SCA, synoptic water quality, biological data
  collected by DNR
• Seems to provide discrimination among the
  subwatershed types encountered in the Upper
  Patuxent River watershed