Human health may be at risk from exposure to ground water contaminated by uranium ore processing. Exposure could occur by drinking water pumped out of a hypothetical well drilled in the contaminated areas. Adverse ecological and agricultural effects may also result from exposure to contaminated ground water. For example, livestock should not be watered with contaminated ground water.A risk assessment describes a source of Contamination, how that contamination reaches people and the environment, the amount of contamination to which people or the ecological environment may be exposed, and the health or ecological effects that could result from that exposure. This risk assessment is a site-specific document that will be used to evaluate current and potential future impacts to the public and the environment from exposure to contaminated ground water. The results of this evaluation and further site investigations will be used to determine a compliance strategy to comply with the UMTRA ground water standards.
RISK SUMMARYIn the area of the Monument Valley site, the Navajo people use ground water as the sole source of water for domestic and agricultural purposes. Access to the ground water is not restricted. However, no current users of the shallow site-related contaminated ground water for domestic and agricultural purposes have been identified. Since people are not exposed there is no risk to human health. This situation will continue if land and water use at the site does not change. It should be noted, however, that several plant species have been identified in the vicinity of the site that are used by the Navajo people as a cultural resource. The potential for adverse health effects to occur from these uses is not evaluated in this document.This risk assessment evaluates possible future health problems associated with exposure to site-related contaminated ground water; the results indicate some health problems could occur if contaminated ground water were used as drinking water. Consequently, it is recommended that the site-related contaminated ground water should not be used as drinking water.Potential impacts of site-related contaminated ground water on agricultural resources indicate that the contaminated shallow ground water would not be a suitable source of drinking water for livestock and there could also be negative impacts on plants irrigated with the contaminated ground water. Additionally, if a pond was created in the future, the contaminated ground water would not be suitable for aquatic life to inhabit.
GROUND WATER QUALITY AND USES
Backqround qround water uualitvBackground ground water quality is the natural quality of ground water if uranium milling activities had not taken place. Background ground water is generally a sodium-bicarbonate type with low total dissolved solids (TDS) and a low sulfate to chloride ratio.
Site-related qround water qualityGround water was sampled in three ground water bearing units ( The contaminated alluvial ground water has high TDS levels in comparison to background lev...