System edges in the geometric network are based on the USGS National Hydrography Dataset
(NHD), which is a comprehensive set of digital spatial data containing information on surface-water
features such as lakes, ponds, streams, rivers, canals, drains, springs, and wells. The NHD data
are filtered to an adequate degree of detail, with streams then separated from canals and drainages
and imported into the Modsim_Streams and Modsim_Canals elements of the Geo-MODSIM
data model. Reservoir nodes are created into the Modsim_ReservoirNodes feature class based