A contractor was accused of rinsing cement off his truck and allowing the rinse water to enter a storm drain operated by the County of Santa Clara. The contractor faced a significant fine. Counsel for the contractor retained us to review the case and provide support in a preliminary hearing. We visited the location of discharge, noted observations, and researched local water quality. The case against the contractor relied on pH readings collected by the inspector. We determined that the measurement recorded by the inspector was within the range of values that could be expected for water from the tap, and that the method of measuring pH used by the inspector did not provide the resolution necessary to differentiate the water in the storm drain from ordinary tap water. As a result, the mediator dismissed the case against the contractor.