"This Assessment Report describes the geographic location and focus of nearly 100 studies of environmental water needs in Arizona, using all relevant sources. It identifies environmental water needs for some rivers and denotes the Arizona rivers where we know little. Defining environmental water needs is the first critical step in the broader process of securing and addressing environmental flows. Through this Assessment Report and the companion Arizona Environmental Water Needs Methodology Guidebook, we aim to clearly describe the science of environmental water demands"--Page 1.

"Determining the best methods for quantifying environmental flow needs depends on what is to be studied as well as how the information will be used.... This guidebook will provide a description of the methodologies used in Arizona to define the environment's need for water. Depending on the geographic context, the time and effort available, and whether the goal is restoration or maintenance of an ecosystem, some methods will be more appropriate for a given application than others. The resulting flows prescribed by each method may be more or less feasible when paired with socio-political considerations or water availability"--Introduction, page 1.