Upland drainage into Hay Slough No flash player has been set up. Please select a player to play Flash videos. Video not playing? Update your browser or download the video clip Charlie Wright talks about the upland drainage into Hay Slough during warm temperatures causing open water. Process Observed: Open WaterGroundwater UpwellingWater Movement Date Process Observed: Wednesday, March 2, 2011 Galleries: Hay Slough Gallery