December 1, 2003

Dioxin and furan contaminated sediments in the Tittabawassee River downstream of the city of Midland pose significant reproductive, embryo, and early life-stage mortality risk to fish-eating birds and mammals according to a recent report commissioned by the Department of Environmental Quality.

The 48-page Tittabawassee River Aquatic Ecological Risk Assessment Report, prepared by Vermont-based Galbraith Environmental Sciences, LLC, was initiated after investigations of river sediments and flood plain soil conducted by the DEQ found dioxin and furan contamination. The contamination is pervasive throughout the Tittabawassee River and its flood plain downstream of Midland and the Dow Chemical plant.

“The report provides critical risk assessment data that will assist the DEQ in determining the impacts and risks to wildlife posed by dioxin and furan contamination and the appropriate response activities needed to reduce those risks,” said DEQ Director Steven Chester.

The conclusions of this study are based on the concentrations of dioxins and furans in sediment and fish collected from the Tittabawassee River and from duck and chicken eggs collected from the Tittabawassee River floodplain.

Specific conclusions reached from the aquatic risk assessment include:

• Carp, catfish, shad, and bass in the Tittabawassee River downstream of Midland are contaminated with dioxin and furans at levels posing serious reproductive impairment to: 1) fish-eating birds and mammals that consume them (even as small portions of their diet), and 2) bird species that are normally insensitive to dioxins and furans.

• Risks of reproductive impairment to fish-eating birds and mammals resulting from dioxin contaminated sediments also exists within the Saginaw River and inner Saginaw Bay, based on the limited amount of sediment data that currently exists.

• Tittabawassee River ecological habitats downstream of Midland are contaminated with dioxin and furans at levels that could result in toxic impacts to exposed wildlife species.

• Concentrations of dioxin and furans measured in waterfowl eggs collected from the Shiawassee National Wildlife Refuge near the Tittabawassee River were much higher than concentrations measured in waterfowl eggs collected from unimpacted areas.

• Concentrations of dioxin and furans confirmed to be present in fish tissue and in waterfowl eggs provide actual site-specific information that supports the findings and conclusions of the aquatic ecological risk assessment.

The 48-page report is now available on the DEQ webpage www.michigan.gov/tittabawassee;  or from the DEQ Saginaw Bay District Office, 503 N. Euclid, Bay City, Michigan; or by calling Sue Kaelber-Matlock, DEQ Remediation and Redevelopment Division, at 989-686-8025, ext. 8303.

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

Revised December 1, 2003 by Pat Watson