Specifications include, but are not limited to: The Brazos River BBASC, the Guadalupe-San Antonio BBASC, and the Colorado-Lavaca BBASC have requested development of a monitoring framework that would provide the ability to make flow regime assessments and evaluate the current environmental flow standards. The goals of the Project described herein are to develop and demonstrate methods and procedures that could be used to assess and evaluate existing environmental flow standards in all seven basin-bay areas. This project has five tasks. Task 1 requires a systematic analysis of the ecological attributes of the flow regime by utilizing existing historical datasets previously collected and used as part of validation studies. This analysis will examine the temporal relationship in the responses of fish, macroinvertebrates, and riparian communities to flow. The purpose of this task is to evaluate the relationship between the antecedent hydrologic regime and the biological community structure and response. Task 2 requires developing and demonstrating in one or more of the basins, where previous data collections have occurred, how retrospective flow analysis can be used to evaluate responses to flow regime components. Retrospective flow analysis can be used to study both short- and long-term changes in the flow regime. For example, the age of larval fish can be used to determine the date and flow conditions when the fish was spawned, hatched, and initiated feeding. Fish growth rates can also be estimated from otoliths, scales, and other hard structures and compared to prior flow conditions. Similarly, the age distribution and growth rates of freshwater mussels, which can be estimated by examining shell cross sections, may be linked to antecedent flow conditions. Task 3 requires developing and demonstrating how trend analysis can be used for both long-term monitoring and shorter-term retrospective analyses of ecology–flow relationships. The Contractor(s) will be required to identify and study multiple indicators that can reveal the influences of various flow regime components. Task 4 requires developing guidance for stakeholders on how the results of the analysis performed for this contract can be applied to future scenarios in which available water is fully permitted and all permitted flows are fully utilized. This is an important task, because in many, if not all, locations where data has been collected to date, the current flow regime is not representative of the flow regime that will exist when the system is fully permitted and permits are fully utilized.