June 7, 2002

Partial results from a study entitled “Baseline Characterization of Saginaw Bay Watershed Sediments” are being released today by the Department of Environmental Quality.

The study was conducted to survey the environmental health of portions of rivers in the Saginaw Bay watershed. This study was conducted separately from the DEQ Environmental Response Division sampling of floodplain soils near Saginaw. The dioxin and furan analyses were done in coordination with Dr. John Giesy, professor of zoology and veterinary medicine, at the National Food Safety Center and Zoology Department at Michigan State University. Funding for this project was provided through the Great Lakes Protection Fund.

River sediments and floodplain soils were sampled from August through December 2001, by the DEQ Waste Management Division and analytical results were completed in May of 2002. Samples were collected upstream of Midland, Michigan, on the Pine, Chippewa, and Tittabawassee Rivers and downstream to the end of the Tittabawassee River just above the junction with the Saginaw River. Samples were analyzed for heavy metals and certain organic compounds including volatile and semivolatile compounds, pesticides, herbicides, polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), dioxins, and furans. The Dow Chemical Company was also provided split samples that were taken by the DEQ.

Dioxin results are presented in total toxic equivalents (TEQs) as a measure of the toxicity of the dioxin family of compounds. River sediments ranged from 1 to 5 parts per trillion (ppt) TEQ above the junction of the Chippewa and Tittabawassee Rivers and from 5 to 2,000 ppt TEQ below the junction. Concentration of TEQ in the sediments varied substantially and appears to be higher in depositional zones occurring within the river.

Floodplain soils were also sampled and analytical results ranged from 2 to 9 ppt TEQ above the junction of the Chippewa and Tittabawassee Rivers and from 300 to 1500 ppt TEQ below the junction. The attached maps show the concentrations and distribution of the samples collected during the study.

Staff from the DEQ is in the process of interpreting the results from this study. They will be integrating these results with existing data and data that are still being collected in a separate Phase II study, which is in progress by the DEQ Environmental Response Division. The DEQ is in the process of determining how best to address potential environmental and human health issues in this area.

"Having this benchmark data will assist the DEQ in its continued evaluation of the Tittabawassee River watershed," said Jim Sygo, chief of the DEQ Waste Management Division.

The full report on the Baseline Characterization of the Saginaw Bay Watershed Sediments study is expected to be completed in late July, 2002.

Editor’s note: DEQ news releases are available on the department’s Internet home page at www.michigan.gov/deq.

Revised June 7, 2002 by Pat Watson