Abstract

Beginning in the late 1990’s, the U.S. Geological Survey began to develop analytical methods to detect, at concentrations less than 1 microgram per liter (µg/L), emerging water contaminants such as pharmaceuticals, personal-care chemicals, and a variety of other chemicals associated with various human and animal sources. During 1998–2005, the U.S. Geological Survey analyzed the following Michigan water samples: 41 samples for antibiotic compounds, 28 samples for pharmaceutical compounds, 46 unfiltered samples for wastewater compounds (dissolved and suspended compounds), and 113 filtered samples for wastewater compounds (dissolved constituents only). The purpose of this report is to summarize the status of emerging contaminants in Michigan waters based on data from several different project-specific sample-collection efforts in Michigan during an 8-year period. During the course of the 8-year sampling effort, antibiotics were determined at 20 surface-water sites and 2 groundwater sites, pharmaceuticals were determined at 11 surface-water sites, wastewater compounds in unfiltered water were determined at 31 surface-water sites, and wastewater compounds in filtered water were determined at 40 surface-water and 4 groundwater sites. Some sites were visited only once, but others were visited multiple times. A variety of quality-assurance samples also were collected. This report describes the analytical methods used, describes the variations in analytical methods and reporting levels during the 8-year period, and summarizes all data using current (2009) reporting criteria. Very few chemicals were detected at concentrations greater than current laboratory reporting levels, which currently vary from a low of 0.005 µg/L for some antibiotics to 5 µg/L for some wastewater compounds. Nevertheless, 10 of 51 chemicals in the antibiotics analysis, 9 of 14 chemicals in the pharmaceuticals analysis, 34 of 67 chemicals in the unfiltered-wastewater analysis, and 56 of 62 chemicals in the filtered-wastewater analysis were detected. Antibiotics were detected at 7 of 20 tested surface-water sites, but none were detected in 2 groundwater samples. Pharmaceuticals were detected at 7 of 11 surface-water sites. Wastewater compounds were detected at 25 of 31 sites for which unfiltered water samples were analyzed and at least once at all 40 surface-water sites and all 4 groundwater sites for which filtered water samples were analyzed.

Overall, the chemicals detected most frequently in Michigan waters were similar to those reported frequently in other studies nationwide. Patterns of chemical detections were site specific and appear to be related to local sources, overall land use, and hydrologic conditions at the time of sampling. Field-blank results provide important information for the design of future sampling programs in Michigan and demonstrate the need for careful field-study design. Field-replicate results indicated substantial confidence regarding the presence or absence of the many chemicals tested. Overall, data reported herein indicate that a wide array of antibiotic, pharmaceutical, and organic wastewater compounds occur in Michigan waters. Patterns of occurrence, with respect to hydrologic, land use, and source variables, generally appear to be similar for Michigan as for other sampled waters across the United States. The data reported herein can serve as a basis for future studies in Michigan.

Posted February 2010