Animas River Valley
— May 14, 2018
This study continues work done in the Animas Valley in Northwestern New Mexico over the past two years that aims to: (1) increase our understanding of geochemical processes related to existing inorganic contamination (i.e. metals) in the Animas River shallow aquifer with implications for potential contamination from specific sources, including the Gold King Mine (GKM) spill, and (2) monitor groundwater conditions to assess contamination due to the GKM spill and historical mining impacts. Previous work analyzed seasonal groundwater fluctuation and groundwater chemistry to characterize the hydrogeologic system and to assess potential impacts to the shallow aquifer from the Gold King Mine spill, which occurred in August 2015. There was no evidence that the GKM spill impacted groundwater quality in the alluvial aquifer. However, continued monitoring was recommended.
For this next phase of the study, we will collect samples from shallow domestic wells throughout the Animas valley between the New Mexico/Colorado border and Farmington, NM. Water samples will be analyzed for major ions, total and dissolved metals, the stable isotopes of hydrogen and oxygen, as wells as stable sulfur isotopes in dissolved sulfate and stable carbon isotopes in dissolved organic carbon. Data loggers that measured water level, temperature and electrical conductance will be installed in selected wells. We will use these data to assess the spatial distribution of redox conditions in the shallow aquifer, to identify water quality changes resulting from river water input and possible contamination related to the GKM spill and legacy acid mine drainage.
Funding for this project comes from the U.S. Environmental Protection Agency, distributed by the New Mexico Environment Department for their Long Term Monitoring Plan.