Auxiliary material for
Optimizing the Scale of Markets for Water Quality Trading
Martin W. Doyle1, Lauren Patterson2, Yanyou Chen3, Kurt Schnier4 and Andrew J. Yates5
1
Nicholas School of the Environment, Duke University
2
3
4
5
Research Triangle Institute, Inc.
Department of Economics, Duke University
Department of Economics, Georgia State University
Department of Economics, University of North Carolina – Chapel Hill
Water Resources Research
Introduction
This supplemental material provides information on the derivation of specific equilibrium
equations used in the analysis, the methods used for the genetic algorithm for finding the optimal
solution, and the background data for the wastewater treatment plants used in the analysis.
1. texts01.pdf Derivation of equilibrium conditions when using trading ratios rather than onefor-one trading rules.
2. texts02.pdf Description of the genetic algorithm used.
3. ts03.pdf Table containing the characteristics of the wastewater treatment plants (WWTP) used
for the analysis.
3.1. Column “Basin”, the river basin containing the WWTP
3.2. Column “ID”, the identification number used for the WWTP, and corresponding to the IDs
used in Figure 1.
3.3. Column “Facility”, the name of the facility used by the EPA in identifying the WWTP (i.e.,
common name)
3.4. Column “State”, the state in the WWTP is located.
3.5. Column “Permitted discharge”, the total discharge permitted by the EPA to be emitted in
MGD. Note that this is in flow, which is a combination of discharge from the plant and the
concentration of nitrogen assumed for that average flow from the WWTP.
3.6. Column “Permitted TN”, the total nitrogen load permitted (in lb/day).
3.7. Column “Source of TN Value”, how the TN value was determined, either based on actual
values given by the EPA or by a regression function derived in the text
3.8. Column “streamflow”, the mean discharge of the segment of stream into which the WWTP
emits
3.9. Column “Estuary N Transfer Coefficient”, the amount of nitrogen emitted from the WWTP
that arrives at the downstream estuary (e.g., 0.46 is 46% of the emitted nitrogen would reach the
estuary)
3.10. Column “TN Load”, the actual total nitrogen that is derived from the stream reach based on
SPARROW modeling approach.