Drinking-Water Quality
Source Water-Quality Assessments (SWQA’s) are a new status activity for Cycle II of NAWQA. In general, SWQA’s are two-year sampling activities wherein the first year involves sampling near the intakes of drinking water from surface- and ground-water sources and analyzing samples for a comprehensive list of primarily anthropogenic organic constituents. The primary objective of year-2 sampling activities focuses on comparing concentrations in source water to concentrations in finished water for anthropogenic organic compounds found to occur most frequently in source waters sampled during the first year of SWQA sampling. Each study unit will work closely with the drinking water facilities to track the retention time to ensure that the same parcel of water is sampled for the finished water. This comparison between untreated and treated water will enable the Program to ascertain, in a general sense, if human exposure of compounds frequently found in source water may be entering the community’s distribution system.
Nationwide, nine surface-water intakes were selected for study and in the WHMI, the Indianapolis Water Company – Indy North water-treatment facility was selected. Selection of surface-water intakes (SW-SWQA) occurred in 2002 and the first year sampling occurred from October 2002 to September 2003 with 17 samples collected. Year 2 sampling for the surface water component began in July 2004 and is scheduled to be completed in June 2005. Constituents sampled for both the ground water and surface water components include heavily used pesticides, polar pesticides, major metabolites of triazines and acetanalides (LCAA), waste-water compounds, and volatile organic compounds.
Sites for the ground-water component of the study (GW-SWQA) were tied to study units involved with the Transport of Anthropogenic and Natural Contaminants study. In the WHMI, 15 wells were selected for sampling during 2002. These wells were in the glacial-buried valley aquifer in the Dayton area. Results of a ground-water flow model were used to identify wells minimally influenced by surface-water infiltration. The first year of samples were collected in November and December 2002. Year two sampling was done in May 2004.
