MINING IN THE GRAND CANYON WATERSHED AND THE IMPLICATIONS ON THE QUALITY OF WATER SOURCES

Recently, a U.S. court of appeals voted to uphold a uranium mining ban in the area immediately surrounding Grand Canyon National Park, however, up to 11 claims in the nearby region could still be eligible for development. Mining in the region has been debated for several decades with opponents claiming that the mining has led to the contamination of water that runs through the canyon which hosts a diverse ecology and is heavily relied upon for drinking water.In order to determine the impact of contaminants in water sources, it is important to collect water quality data from past measurements and survey. There are several agencies that have conducted water quality testing in and around the canyon, but there is little sharing of this data, making it difficult to determine the extent of contamination.Over the last two years, we have developed a database of water quality data from the region with the aim of consolidating the data sources and making it available to researchers. From this database, we find that contaminant parameters including: arsenic, uranium, and selenium for several water sources have exceeded the U.S Environmental Protection Agency’s drinking water Maximum Contaminant Levels (MCL). We have investigated trends in the aqueous contaminant concentrations and possible correlation to the type of waterbody (streams, creeks, and springs), as well as natural events, such as precipitation. The data suggests that the region is susceptible to elevated uranium levels, and any future mining in the region should be approached carefully and with a thorough assessment of historical contamination.