GIS for source water assessment and nonpoint source modeling in the Las Vegas Valley (Nevada)

This thesis develops a better understanding of issues related to surface water contamination and protection of drinking water sources in the Las Vegas Valley. A Geographic Information System (GIS) was used to identify source water protection zones and to estimate nonpoint source loads for the entire watershed.; The extent of the source water protection zones is represented by the valley's dry weather flows. After source water protection zones were defined, field work and GIS defined the potential contaminant sources and land uses within the protection zones.; The GIS nonpoint source model shows that roads account for approximately 25% of the Total Nitrogen and 18% of the Total Phosphorus from nonpoint sources. Analysis suggest that a disproportionately high amount of nutrient loads have their origin within the source water protection zones. Approximately 10 to 7 percent of nutrient loads originate in the 5% of the total watershed area represented by protection zones.