The purpose of this presentation is to describe a new water-audit approach and decision-support system based on spatial mapping of soil volumetric water content (VWC) during a dry period when the irrigation system uniformity of water application would be exhibited.  In contrast to the traditional catch-can audit, the soil VWC-based audit considers any factor influencing soil water distribution (irrigation system design and performance, wind distortion, runoff, high ET areas, etc.) and is based on wall-to-wall assessment of the whole area using a sample grid of 2.5 x 2.5 m. Data collection is performed via the mobile Toro Precision™ Sense 6000 (patent pending) data acquisition unit with multiple sensor for soil VWC, salinity, plant performance, penetrometer resistance, and topography; all with GPS labeling.  A practical, step-by-step approach is presented for the new water-audit method for complex turfgrass sites, such as a golf course, with the ultimate deliverable being a decision-support system report for the end user. Analysis of soil VWC spatial variability includes defining the degree of variability at three critical spatial levels, using various geographic system information GIS) statistical and visual metrics. The three spatial levels are: a) whole area (e.g., whole fairway, green, and tee); b) each individual irrigation head to assess any problems and potential causes; and c) each irrigation zone with attention to head spacing and system performance. Practical decision-support system information includes: how uniform is soil VWC status at these spatial levels; and recommended corrective measures or fixes at each spatial level.