Open water in slough across from Walt Peirce's cabin A closer view of the open water area in the slough across from Walt Peirce's cabin makes the orange colored iron oxidizing bacteria slightly more visible. Process Observed: Iron Oxidizing BacteriaOpen WaterGroundwater Upwelling Date Process Observed: Saturday, March 31, 2012 Galleries: Slough across from Walt Peirce’s cabin Gallery