2007 Annual Report 1a.Objectives (from AD-416) To develop information on the impact on soil physical properties when using low quality waters for irrigation and determine predictive relationships based on statistical analysis of lab and field experiments. 1b.Approach (from AD-416) To conduct laboratory and field research as needed to determine the impact of low quality waters on soil properties of California soils. Documents SCA with University of California-Riverside. Formerly 5310-61000-012-05S (FEB 07) 3.Progress Report This report serves to document research conducted under a Specific Cooperative Agreement between ARS and the University of California, Riverside. Additional details can be found in the report of the parent project 5310-61000-012-00D. We examined the impact of waters varying in SAR and pH on infiltration rates into a noncalcareous arid-land soil. We examined the impact of degraded waters in both irrigation and rain irrigation systems. For the rain- irrigation systems we alternated irrigation with degraded water and rainfall, using our rainfall simulator and deionized water. Soils were dried between irrigations to a fixed matric potential, allowing simulation of field wetting and drying conditions. Infiltration rates decreased with increasing SAR and pH, and decreased with time. Since we are on-site at the UCR campus we participate in weekly meetings with the UCR employees. The research site is at our facility, and as cooperators we assist in the conduct of the experiments.