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Quantification of the contribution of nitrogen from septic tanks to ground water in Spanish Springs Valley, Nevada

Scientific Investigations Report 2006-5206

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Abstract

Analysis of total dissolved nitrogen concentrations from soil water samples collected within the soil zone under septic tank leach fields in Spanish Springs Valley, Nevada, shows a median concentration of approximately 44 milligrams per liter (mg/L) from more than 300 measurements taken from four septic tank systems. Using two simple mass balance calculations, the concentration of total dissolved nitrogen potentially reaching the ground-water table ranges from 25 to 29 mg/L. This indicates that approximately 29 to 32 metric tons of nitrogen enters the aquifer every year from natural recharge and from the 2,070 houses that use septic tanks in the densely populated portion of Spanish Springs Valley. Natural recharge contributes only 0.25 metric tons because the total dissolved nitrogen concentration of natural recharge was estimated to be low (0.8 mg/L). Although there are many uncertainties in this estimate, the sensitivity of these uncertainties to the calculated load is relatively small, indicating that these values likely are accurate to within an order of magnitude. The nitrogen load calculation will be used as an input function for a ground-water flow and transport model that will be used to test management options for controlling nitrogen contamination in the basin.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Quantification of the contribution of nitrogen from septic tanks to ground water in Spanish Springs Valley, Nevada
Series title:
Scientific Investigations Report
Series number:
2006-5206
Edition:
-
Year Published:
2006
Language:
ENGLISH
Contributing office(s):
Nevada Water Science Center
Description:
12 p.
Number of Pages:
12