Details

Autor(en) / Beteiligte

• Wann, Alexander C

Titel

Best management practices to protect groundwater quality in Goshen County, WY: Trend analysis and information transfer

Ort / Verlag

ProQuest Dissertations Publishing

Erscheinungsjahr

2012

Link zum Volltext

• ProQuest

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Influx of nutrient pollutants into groundwater from intensive agricultural production is a historic challenge facing water resource managers worldwide. This issue is prevalent in the areas surrounding Torrington, Wyoming, where nitrate (NO3−) concentrations in excess of the EPA Maximum Contaminant Level (MCL) (>10 mg L−1 as N) in the domestic groundwater supply have been reported for over 20 years. Best Management Practices (BMPs) such as sprinkler irrigation and split nitrogen (N) fertilizer applications were widely-implemented in the 1990s to reduce further groundwater contamination. The first objective of this research (Dornak, 2010) was to evaluate NO3− persistence at varying soil depths in flood/furrow-irrigated versus sprinkler-irrigated systems (via soil lysimetry), and conduct a temporal analysis of NO3 − trends in groundwater in 2003–2005. This effort also established the Network Concept, utilizing active community stakeholder involvement in the design and implementation of the study. Results suggest that NO 3− persists deeper in soils in furrow-irrigated systems than sprinkler-irrigated. The second objective (Wann, 2012) was to use a PROC MIXED model in SAS® to conduct a trend analysis of groundwater monitoring data for NO3− concentrations in 2003–2011, to evaluate BMP impact on groundwater NO3 − from 21 wells in and near the city of Torrington. Results indicate that 12 of 21 wells exhibited a statistically significant trend over time (α=0.1). Seven wells exhibited a significant decrease (none with a 2003–2011 mean concentration that exceeded the MCL) and 5 wells exhibited a significant increase (2 with a mean concentration that exceeded the MCL). Of the remaining 9 wells, 3 displayed mean concentrations equal to or in excess of the MCL. Findings also estimate a 17–19% increase in sprinkler irrigated acreage in the study area from 1990 to 2009. Results suggest that groundwater quality in the NPRV watershed has not degraded, but rather shown some improvement. These results were presented to project stakeholders in a public meeting in April, 2011 and subsequent trend analysis results will be presented to stakeholders in 2012.