Edition 1.0 June 2006.Includes bibliographical references (pages 42-44).For several years, Colorado State University has been documenting flow and water quality conditions in Colorado's Lower Arkansas River Valley with the goal of providing data and models that water users and managers can use to enhance both agriculture and the environment in the Valley. Extensive measurements are being made in the field, and some previously gathered data are still undergoing analysis. Models of the irrigated stream-aquifer system are under development, calibration, and refinement. Potential strategies for improving conditions in the river valley are being formulated and investigated. Small-scale pilot testing of solutions are scheduled to begin during the summer of 2006. The results presented in this technical report are published as a benchmark to document completion of the first phase of this work. They also provide broad information in support of current decision making in the river valley and hopefully will stimulate feedback and discussion. Some of the information presented here is provisional since it is still undergoing refinement and expansion.This research was partially funded by the U.S. Department of the Interior Geological Survey and Colorado Water Resources Research Institute Project on Grant Number 01HQGR0077, Project 2002CO6B and the Colorado Agricultural Experiment Station project COL00694 entitled 'Multidisciplinary Research on Salinity Issues in the Arkansas River Valley.