WorldWide Drilling Resource

Assessing the Quality of America’s Groundwater Adapted from Information by U.S. Geological Survey The U.S. Geological Survey (USGS) started a complex undertaking in 2012 seeking to survey the quality of America’s largest drink- ing water resource. The survey is focused on assessing groundwater throughout the country by extensive aquifer sampling, which will be carried out through 2023. Roughly half of the nation’s population relies on groundwater as their source for drinking water. Thus, as the pop- ulation grows, the need for a high-quality drink- ing water supply becomes increasingly urgent. USGS scientists are analyzing water quality of untreated water from wells in prin- cipal aquifers. Though most consumers receive treated water from local utilities to meet federal drinking water standards, under- standing what constituents are in untreated water can help decision makers manage and treat water resources. The comprehensive sampling is targeting wells which tap deeper groundwater because the data can be used to explain how and why aquifer vulnerability to contamination varies across the nation. The samples will also give insight to information about geology, hydrology, geochemistry, and chemical and water use. In-depth, regional-scale assessments will be conducted on 20 of the most heavily used aquifers in the nation. Groundwater quality results for five principal aquifers sampled in 2012 and 2013 have already been pub- lished. One or more inorganic constituents exceeded human health benchmarks in 4- 20% of samples collected from the five prin- cipal aquifers. Organic contaminants were not found at levels of concern, while con- taminants from geologic sources - primarily trace elements such as arsenic, fluoride, and manganese - were the most common to exceed human health benchmarks. Radio- active constituents exceeded human health benchmarks by small percentages in all but one of the five aquifers studied, and the nutrient nitrate was the only constituent from man-made sources which exceeded the human health benchmark. What is the qual i ty of the nat ion’s groundwater? Is it getting better or worse? What factors affect the quality of this vital resource? Over the next few years, results wi l l be released for additional principal aquifers which are important sources of drinking water for the nation as the National Water-Quality Assessment Project continues to address these central questions. 23 WorldWide Drilling Resource ® AUGUST 2017