Kardos, Josef Sy. Effect of water quality model uncertainty on the Passaic total maximum daily load and water quality trading program for total phosphorus. Retrieved from http://dx.doi.org/doi:10.7282/T3K937QX
DescriptionWater quality modeling is a major source of scientific uncertainty in the Total Maximum Daily Load (TMDL) process. The effects of these uncertainties extend to water quality trading programs designed to implement TMDLs. This is the first study to examine the effects of water quality model uncertainty on a nutrient trading program. The method introduced in this study involved application of simple statistical tools to assess the credibility of the uncertainty analysis when compared to observed data. The method's efficiency and practicality directly address a main obstacle that has hindered a wider practice of uncertainty analyses of water quality models.
This study identified how water quality model uncertainty affects outcomes related to the Non-Tidal Passaic River Basin TMDL for total phosphorus (TP) and potential trades of TP between wastewater treatment plants (WWTPs). The TMDL margin of safety was found to be sufficient with respect to attaining dissolved oxygen (DO) surface water quality standards at Dundee Lake, and achieving a 70% reduction in diverted TP load from the Wanaque South intake to the Wanaque Reservoir. Although the TMDL scenario showed greater than 10% probability of exceeding the target for chlorophyll-a (chl-a) at Dundee Lake, the efficacy of TMDL measures was clearly demonstrated when compared directly to actual conditions in the critical drought period of Water Year 2002. The uncertainty analysis found no evidence to suggest that the outcome of trades between WWTPs, as compared with command and control regulation, will significantly increase uncertainty in the attainment of DO surface water quality standards, site-specific chl-a criteria, and reduction targets for diverted TP load at affected potential hot spots in the watershed. Each simulated trading scenario demonstrated parity with or improvement from the baseline at the TMDL critical locations and low risk of hot spots elsewhere.
Finally, research on risk communication techniques was synthesized to help the New Jersey Department of Environmental Protection in its future public participation efforts on the Passaic water quality trading program. A strategy based on the principles of 'outrage management' was outlined for conducting a public meeting.