- 2016 American Society of Civil Engineers. Environmental flow standards established according to a consensus-based, legislatively mandated process are being incorporated in the water rights permitting system for selected priority river systems in Texas. The flow standards for several of the rivers have been simulated as a part of a university research study using the new daily version of the Water Rights Analysis Package (WRAP) modeling system with modified input data sets from the Texas Commission on Environmental Quality (TCEQ) Water Availability Modeling (WAM) system. Metrics have been evaluated using time series of simulated streamflows and flow targets to characterize the engagement and attainment of the environmental flow standards. The metrics help determine the extent to which the standards are achieved within a river system water allocation simulation and enable the comparison of results between the different environmental flow regime components, different locations, and alternative river system development scenarios.