Survey of unregulated drinking water sources on navajo nation

Water hauling is widespread on Navajo Nation. Approximately 30% of Navajo households do not have potable water and must haul drinking water from outside sources. In addition, some connected households choose to haul water. Many obtain water from unregulated, untreated sources that are not approved for human consumption and may contain natural chemicals, bacteria and other contaminants. In order to determine the quality of water used by Navajo households that haul water, we tested unregulated water sources (livestock wells and springs) used for hauling drinking water on Navajo Nation.

We systematically selected and sampled 229 water sources to attain a representative geographical distribution across a region of Navajo where natural arsenic and uranium in groundwater are likely to occur. We attempted to test water from each source for bacteria and inorganic chemicals (IOCs).

Of 188 water sources tested for bacteria, 40 (21%) were positive for E. coli and 144 (77%) were positive for total coliforms. Of 199 sources tested for IOCs, 44 (22%) exceeded one or more of the primary drinking water standards. The most frequent exceedance was arsenic (24 [12%] sources) followed by uranium (9 [5%] sources). The highest arsenic level was 190ug/L and the highest uranium level was 260ug/L.

This study demonstrated considerable bacterial and chemical contamination of unregulated drinking water sources. These findings suggest that Navajo households that consume water from unregulated sources are at risk for exposure to pathogenic bacteria and harmful levels of arsenic, uranium and other contaminants that may affect health.