The Lawrence Livermore Laboratory has conducted two underground coal gasification experiments at its Hoe Creek site in northeastern Wyoming during the Hoe Creek 2 experiment, roof collapse and the inadvertent gasification experiments at its Hoe Creek site in northeastern Wyoming During the Hoe Creek 2 experiment, roof collapse and the inadvertent gasification of an overlying coal seam resulted in the interconnection of three aquifers, including the two gasified coal seams. This situation has lead to changes in the local hydrology and in the dispersal of reaction-product contaminants.