Long Term Groundwater Monitoring in the Animas Valley
Our agency has been collaborating with the New Mexico Environment Department (NMED) on a hydrogeology study along the Animas River in New Mexico in response to the Gold King Mine spill, which occurred in August 2015. The water released from the spill was loaded with dissolved metals and contaminated sediments, which posed a possible risk to groundwater quality in the Animas Valley. For the first phase of this study we measured water levels and collected water samples for geochemical analysis from existing wells in the shallow alluvial aquifer along the Animas Valley north of Farmington, NM. From January 2016 through June 2017, data were collected at different seasons, which were determined based on Animas River flow conditions.
The objectives of the first phase of this study were to:
- Characterize the hydrogeologic system, which includes the determination of groundwater flow directions, hydraulic gradients, and recharge sources, and the assessment of groundwater/surface water interactions
- Identify areas along the river where the river may be losing water to the shallow aquifer
- Assess the possible impacts of the Gold King Mine spill to shallow groundwater
Results from this study have helped to construct a working conceptual model of the hydrogeologic system that includes the identification of the primary recharge sources and mechanisms, groundwater flow paths and some groundwater contaminants of concern. There was no evidence that the GKM spill impacted groundwater quality in the alluvial aquifer. However, continued monitoring was recommended.
For the next phase of this study, which will start in the Fall of 2018, we will continue to monitor groundwater chemistry in the shallow aquifer to evaluate and identify water quality changes resulting from river input and possible contamination related to the GKM spill, legacy acid mine drainage, and other possible sources.
Funding for this project is from the U.S. Environmental Protection Agency (U.S. EPA), distributed through the NMED.
For more information, please contact:
Dr. Talon Newton, Hydrogeologist