NAWQA Liaison Meeting

USGS held a meeting this week with stakeholders to share information about the National Water-Quality Assessment (NAWQA) Project’s accomplishments on monitoring, modeling, mapping and predicting groundwater quality.  These key topics were included:

• The Quality of Deep Groundwater—Over the past three years, 1000 deep public-supply wells have been sampled and analyzed for a large number of regulated and unregulated contaminants, selected emerging contaminants, geochemical indicators, and tracers of groundwater age.  Since 2012 the NAWQA program has shifted some of their focus from shallow and domestic well depths to deeper aquifers used for public water supply.  These data are now sufficient to begin to report about the water quality. Fortunately, the vast majority of these deeper samples indicate very low levels or no detections of contaminants.  The most prevalent at high concentrations are trace inorganic elements of natural origin.  Even then, the high concentrations are a very low percentage of total samples.
• Maps of Groundwater Corrosivity—By evaluating water-quality data from more than 20,000 sampling locations, USGS has created the first nationwide maps indicative of where groundwater is potentially corrosive. This can help indicate where untreated or minimally treated groundwater sources could contribute to lead corrosion in household plumbing.  These national maps of groundwater corrosivity indicators should be available this summer.
• Groundwater-Quality Trends Mapper—Determining whether the quality of the Nation’s groundwater has become better, worse, or stayed the same during a 10-year time period has been an important activity of the NAWQA project. An online mapper has been developed to facilitate interactive exploration of groundwater-quality trends nationwide.  USGS showed a beta version of its soon-to-be released Groundwater Quality Trends Mapper.  Users will be able to look at specific contaminants in various aquifers across the country and also download detailed data for each of the sites.  The mapper should go live in a few weeks.
• Geochemical Conditions for Predicting Contaminants—Reduction/Oxidation (redox) processes affect the chemical quality of groundwater in all aquifer systems. Understanding the spatial distribution (horizontal and vertical) of redox conditions in aquifers is essential when assessing groundwater quality. With adequate information on the geochemical conditions in the lower aquifers, USGS will be able to model the fate and transport of contaminants from upper aquifers.  Ultimately this modeling will be able to fill in gaps in water quality data in the lower aquifers.
• Effects of UOG Production on Groundwater Quality—The potential effects of unconventional oil and gas (UOG) production on groundwater quality used for drinking-water supply are being evaluated in three focus areas:  The Haynesville Shale (LA and TX), Fayetteville Shale (AK), and Eagle Ford Shale (TX); and in future years will be evaluated in two additional areas: Bakken Formation (ND, MT) and Marcellus Shale (NY, PA, WV, OH). These studies compare the quality of groundwater in areas that are proximal to UOG production (< 1 km from shale gas wells) to the quality of groundwater in areas that are distal from UOG production (> 1 km from shale gas wells).  Preliminary results from two areas indicate that there is not a significant difference in methane levels in domestic wells close to gas wells compared to those further away.  Also, methane in these wells seems to be from shallow sources (created by biological activity) rather than deeper drilling activity.  Other constituents, like benzene, appear to be from the accumulation of contamination from very diverse natural sources over many hundreds of years versus coming from young water impacted by oil and gas production.  Results will be published after the completion of monitoring in the Eagle Ford Shale in 2016.

Information about these projects and other NAWQA activities are available on the NAWQA website.  ASDWA has already asked USGS to share information about many of these projects at the ASDWA Annual Conference in Milwaukee this October.