The researchers covered 550 miles to determine the health of the river from Fort Yukon to Kaltag.
The state Department of Environmental Conservation was joined in the survey by the University of Alaska, U.S. Geological Survey, National Park Service, Environmental Protection Agency, U.S. Fish and Wildlife Service, Bureau of Land Management and Yukon River Inter-Tribal Watershed Council.
Crews took water samples at 50 locations and conducted habitat, sediment and biological surveys at 550 sites.
A DEC spokesman says results for the water and sediment samples should be available in December and evaluation of biological samples may take up to a year.
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