About this map:

This map shows only low gradient flow portions of streams and rivers in southern Guam. More specifically, it indicates areas where 1) flow is slow across flat or gently sloping terrain, 2) is not interrupted by cascades and waterfalls, and 3) might be influenced by estuarine saltwater wedges extending inland from the ocean. Such areas represent unique freshwater habitats distinct from upstream areas characterized by higher gradient flow. The GIS data used to create this map was derived from drainage network data developed by Government of Guam Bureau of Statistics and Plans, by removing portions of all streams that are upstream from first cascades or waterfalls. The GIS layer was made by Island Research & Education Initiative specifically for the purposes of this on-line atlas.