Water Quality Trading in the Lower Delaware River Basin: A ...

• The Cost to benefit ratios of BMPs are site specific. Local conditions not only
affect the pollutant removal capability of a BMP but also the construction and
operating cost.
• Some BMPs, especially non structural BMPs, are difficult to monitor and there
are no widely-accepted definitions or techniques for evaluating their performance.
Therefore, site specific monitoring plans are often needed and appropriate.
• The effectiveness of BMP’s that rely on reducing pollutant exports will decrease
with time. Therefore, specific time limits need to be established when BMP’s are
used for trading.
An additional issue that arises with NPS trades is whether the credit is given for the
input or export of the pollutant (Shortle and Ambler 2001). With input credits, regulators
assign a credit value for practices that reduce or eliminate the application (e.g. inputs) of
chemicals, fertilizers, of other pollutants. Export credits are based on the reduction in
pollutants leaving a specific area. The administration, monitoring, and enforcement for
input credits is relatively straight forward. The evaluation of export credits relies on
quantifying the transport of pollution from the landscape. Moreover, calculating the
change in pollution inputs from a new wetland, a new traffic pattern, or land cover
change is more difficult than quantifying the reduction of pollutant load by reducing the
application of a chemical, fertilizer, flow, etc. Therefore, the value of input or export
credits is case specific and will have to be evaluated for each situation. Table 2-15
provides a list of useful websites that contains information about BMPs.
Table 2-15: Web Sites for Information on Best Management Practices
Description Site Address
ASCE BMP Database http://www.bmpdatabase.org
MD Stormwater Design http://www.mde.state.md.us/programs/waterprograms/
Manual
sedimentandstormwater/stormwater_design/index.asp
EPA Management
Measures for NPS
http://www.epa.gov/owow/nps/urbanmn/index.html
EPA Summary of Urban
Storm Water BMPs
http://www.epa.gov/ost/stormwater
EPA Urban Stormwater http://www.epa.gov/waterscience/stormwater/montcomple
BMP Monitoring
te.pdf
PA Stormwater BMP http://www.dep.state.pa.us/deq/subject/advcoun/stormwat
Manual
er/stormwatercomm.htm
Villanova Urban
Stormwater Partnership
http://www.villanova.edu/vusp
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