Low Level Organic Chemicals in Surface-Water Sources of Drinking Water Presenters Gregory C. Delzer Lead Scientist, U.S. Geological Survey Thomas Jacobus General Manager, Washington Aqueduct Timothy L. Miller Moderator, U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program U.S. Department of the Interior U.S. Geological Survey

Study Locations Slide #2 Clackamas River Elm Fork Trinity River Cache la Poudre River Truckee River White River Chattahoochee River Neuse River PotomacRiver Running Gutter Brook

Compounds Monitored Slide #3 Gasoline related Personal care and domestic use Solvents Insecticides and degradates Herbicides and degradates Pavement- and combustion-derived Disinfection by-products Fungicides Plant- or animal-derived biochemicals Refrigerants and propellants Fumigant related Organic synthesis Manufacturing additives Number of Compounds Number in group Number with Health- Based Screening Levels Number with Maximum Contaminant Levels

A diverse group of compounds are present in source water at low concentrationsA diverse group of compounds are present in source water at low concentrations Occurrence and concentrations in source water and finished water were often similarOccurrence and concentrations in source water and finished water were often similar Samples typically contained mixtures of compoundsSamples typically contained mixtures of compounds Key Findings Slide #4

Diverse groups of compounds detected in source water Slide #5 Gasoline related Personal care and domestic use Solvents Herbicides and degradates Disinfection by-products Fungicides Plant- or animal-derived biochemicals Organic synthesis Manufacturing additives Number of Compounds Detected 5 15 Number in group Number with Health- Based Screening Levels Number with Maximum Contaminant Levels

Concentrations are low in source water 3% greater than 1 ppb 21% 76% less than 0.1 ppb ~ 130 compounds detected Slide #6 0.1 to 1 ppb

Compounds in Source Water Were Often in Finished Water More commonly detected in finished water Slide #7 Similar occurrence in source and finished water Less commonly detected in finished water

Concentrations of Some Compounds are Similar for Source and Finished Water Slide #8 Source Water, ppb Finished Water, ppb MCL Atrazine Fipronil 1:1 0.1

Seasonal Changes in Stream Water Were also Observed in Finished Water Slide #9

Slide #10 Most Samples of Source and Finished Water Contained Mixtures of Compounds

Land Use Influences Mixtures Slide #11 Percentage of agricultural and urban land use in watershed Median number of compounds in a sample Truckee River White River

A diverse group of compounds are present in source water at low concentrationsA diverse group of compounds are present in source water at low concentrations Occurrence and concentrations in source water and finished water were often similarOccurrence and concentrations in source water and finished water were often similar Samples typically contained mixtures of compoundsSamples typically contained mixtures of compounds Key Findings Slide #12

Greg Delzer, HydrologistGreg Delzer, Hydrologist Jim Kingsbury, HydrologistJim Kingsbury, Hydrologist Donna Myers, Chief, NAWQA ProgramDonna Myers, Chief, NAWQA Program Contact Information Slide #13