ASSESSMENT OF SAN JUAN RIVER HEALTH AFTER GOLD KING MINE SPILL

One of the major environmental problems associated with surface mining is production of a highly acidic and metal-rich solution called Acid Mine Drainage (AMD). If left untreated AMD can severely damages the aquatic system. One of the biggest AMD spills in the U.S. occurred on August 6, 2015, when 3 million gallons of AMD water was accidentally released into the Animas River from abandoned Gold King Mine located outside of Silverton, Colorado. The spill temporarily changed the color of the river to orange. The contaminated water flowed down the Animas River, into the San Juan River in New Mexico, was carried into the Colorado River and ended up in Lake Powell in Utah. The Navajo Nation Commission on Emergency Management issued a state of emergency declaration in response to the spill. The effects of the Gold King Mine spill on the Navajo Nation have included damage to their crops, home gardens, and cattle herds which ceased irrigating their crops from the San Juan River. People living along the Animas and San Juan rivers were advised to have their water tested before using it for cooking, drinking, or bathing. The spill was also expected to cause major problems for farmers and ranchers who rely on the rivers for their livelihoods. The long-term impacts of the spill are unknown, as sedimentation is expected to dilute the pollutants as the spill cloud moves downstream. This study conducted a desk-top evaluation of stream “health” in the San Juan River system that crosses the state lines of Colorado, New Mexico, Utah, and Arizona and flows through tribal lands. In 2016, benthic invertebrate surveys were conducted at San Juan River monitoring sites in the Navajo Nation, and those data are available to the public. Biological indices were calculated using these benthic invertebrates following the guidance of each states’ regulatory agencies, and the results were compared to evaluate how the sites would be classified in terms of “impairment” by each state’s bio criteria method. Our results showed the nature of resiliency from the microorganisms over the time and their recovery trend.