Josie grigsby
Hydrogeochemistry of Natural Acid Rock Drainage in the Tobacco Root Mountains, SW Montana
This study investigates the hydrogeochemistry of the East Fork of the South Boulder River (EFSBR) in the northern Tobacco Root Mountains, Madison County, Montana. The upper 5 km of the main stem of the EFSBR is acidic (pH < 5), and since no mining has taken place in the area, this phenomenon is referred to as Natural Acid Rock Drainage (NARD). Dissolved concentrations of several trace metals, including Al, Cd, Cu, and Zn, are highly elevated, and exceed chronic aquatic life standards by 2-3 orders of magnitude. Unsurprisingly, the EFSBR appears to be devoid of trout. High mountains (up to 10,500’) bounding the valley harbor a number of small rock glaciers and other periglacial features that influence the hydrogeology and chemistry of the watershed. Seasonal melting of buried ice provides a steady flow of cold water in the hot summer months, during the same time period that neighboring drainages are drying up. Additionally, rock glaciers act as efficient chemical reactors, affecting the severity of acidic drainage. Neutralization of the acidic water by alkaline tributaries results in the precipitation of aluminum hydroxysulfate (basaluminite), which covers the streambed with a vivid white mineral coating, and can act as a natural sink for other solutes such as arsenic. Pristine catchments exhibiting NARD can serve as a reference site for establishing baseline water quality conditions for restoration in areas impacted by mining or other anthropogenic disturbances where historical data does not exist. As climate change continues to alter our natural environment, especially in high elevation areas, instances of NARD are predicted to increase globally. Deeper understanding of the processes driving NARD will provide guidance for managing water resources in mountain communities into the future, and insights into necessary changes in remediation methods in disturbed watersheds.
Josie was born and raised in Montana. She and her two sisters spent as much time in the outdoors as possible, cultivating a lifelong fascination and love of the natural world. She attended MSU Bozeman where she continued to spend her free time outside, enjoying all the recreation opportunities the Bozeman area had to offer. After graduating with a bachelor's degree in Snow Science, she spent several years traveling and working before returning to school at MT Tech to get a masters in Hydrogeology and a certificate in Ecological Restoration. She now spends her time caring for her two adorable old dogs and exploring the Butte area on skis, bike and foot. Her goals for the future remain focused on improving the world around us while fulfilling her curiosities and pursuit of adventure.