NITRATE ANALYSIS OF THE ASHTON IDAHO REGION

A groundwater field study to assess nitrate contamination, performed by undergraduate students at Brigham Young University – Idaho (BYU-Idaho) has been underway from 2006 to present within the Ashton groundwater priority area designated by the Idaho Department of Environmental Quality Area of interest for this study include the region east of Ashton, bounded on the north by the Henry's Fork of the Snake River, and on the south by the Fall River. During this time period 28 wells have been visited yielding 165 samples.

Field procedures include measuring, when accessible, depth to water table, monitoring pumped water to verify samples are fresh, collecting samples to be returned to the lab for cation and anion analysis, and deployment of continuously monitoring probes to identify temporal variations in groundwater conditions.

Laboratory analysis of collected samples were performed by students at BYU-Idaho using ion chromatographs and atomic absorption. Using a geographic information system, maps were generated to indicate well positions relative to the bedrock geology and to display observed concentrations of nitrates. Subsurface correlations and resulting cross-sections of the geologic strata between the wells were generated using drillers logs.

Continuously monitoring probes were preset at a sampling rate of one to two hours. Data sets from the probes include water temperature, nitrate concentration, conductivity, water table fluctuation, and pH level.

The data that were collected during the three year sampling period are being analyzed to determine regions of elevated nitrate levels, relationship between nitrate contamination and bedrock geology, and variations of contaminate levels during temporal changes.

The ultimate goal of the Ashton Groundwater Study is to gain a better understanding of the proliferation of nitrate contamination in the Ashton, Idaho region and the role of sub-surface geology in contaminate transport and concentration.