This study discusses the monitoring requirements of an effluent credit trading system that allows point source discharges to purchase effluent reductions by financing agricultural nonpoint source best management practices. It describes the results of a national survey of existing trading programs that assessed how each program determines nonpoint source baseline pollutant discharges, pollutant reductions attributable to best management practices, verification of best management practice(s) installation and maintenance activities, and how often this verification is performed. This study surveyed the nonpoint source discharge monitoring programs of several of the successful effluent credit trading systems in the U.S. It documents and discusses specific characteristics of nonpoint source pollutant discharge monitoring strategies. Finally, this thesis compares trading program discharge monitoring characteristics to the current Virginia Cost-Share nonpoint source monitoring program. The goal of this study is to recommend elements of a nonpoint source discharge monitoring strategy to the Commonwealth of Virginia that can be used in a trading program of its own. The study shows that the majority of existing effluent credit trading programs use watershed models and land use evaluation algorithms to indirectly monitor nonpoint source pollutant discharges on a watershed basis rather than relying on empirical sampling and analysis activities for individual farms of fields. Monitoring takes a variety of forms to provide the diverse information necessary to indirectly determine nonpoint source discharges. Most trading programs monitoring strategies are no more comprehensive than agricultural cost-share programs even though many stakeholders believe that a trading program's monitoring activities should be exact enough to determine contributions from individual nonpoint sources to support the payments for individual activities. This objection is a barrier to the acceptance of trading programs by the public. A Virginia trading program must enhance its agricultural best management practice cost-share program monitoring practices to track nonpoint source discharges from individual farms or fields to be accepted and successful. / Master of Engineering