Collection of arsenic and associated geochemical data important to occurrence and mobility of arsenic in groundwater used for public supply in southern Carson Valley, Douglas County, Nevada

Science Center Objects

The Nevada Water Science Center (NVWSC) is increasing the spatial understanding of the distribution of arsenic and important geochemical information in groundwater resources near select water-supply wells in southern Carson Valley by collecting groundwater samples to complement the existing dataset (2006 – 2015).

To further characterize and develop a better understanding of factors influencing the mobility of arsenic in the southern Carson Valley aquifer, the USGS is collaborating with the Carson Water Subconservancy District to evaluate the distribution of arsenic and other geochemical parameters important to its mobility near pubic supply wells in southern Carson Valley. To maximize the applicability of the data collection effort, the USGS is requesting information from Douglas County water purveyors regarding wells they are most concerned with regarding pumping effects and water chemistry.

The final well selection will be made based on aquifer penetration depth of the available wells in order to maximize the spatial and sampling-depth representation within the 4 square mile (mi2) buffer area surrounding the selected water-supply wells. In the event that the specified number of wells representative of each penetration depth representation within the buffer area are not available, the buffer area may be expanded as appropriate.

Ideally, three wells representing shallow, moderate, and deep penetration depths within the buffer area surrounding the selected water-supply well will be sampled. The “key” water supply well will be selected in consultation with Douglas County water purveyors.

Samples will be analyzed by USGS Nevada Water Science Center Staff (alkalinity, DO, pH, specific conductance and temperature), the USGS National Water Quality Laboratory (ammonia, chloride, manganese, nitrate, nitrite, DOC, orthophosphate, dissolved phosphorus, and sulfate), RTI Laboratories (arsenic speciation), and National Research Laboratory, Boulder, Colorado (iron speciation).