Vertical temperature differences in Three-Mile Slough, during a five-day period in June 1999. The west piling and the east piling were each fitted with three thermistors: Ti, at the level of the transducer; T3, one meter below the transducer; and T1, 1.5 m above the transducer. There is evidence for substantial thermal gradients above the transducers, with some sort of daily or tidal cycle.