A discharge from a private dam on the Pigeon River near Vanderbilt was responsible for a potentially significant fish kill downstream, Department of Natural Resources fisheries officials said today.

The discharge, which began Sunday night, flushed sediment from above the dam that is located on the property of Song of the Morning Ranch near Sturgeon Valley Road in Otsego County. The fish were killed either by the sediment or thermal shock, said DNR fisheries biologist Dave Borgeson.

Fish of numerous species, including brown trout up to 19 inches, were found dead, Borgeson said. Electro-fishing by DNR personnel failed to produce enough live fish to make a population assessment in the water for about two miles downstream from the dam.

"We will be going farther downstream Thursday to see how far the fish kill extends," Borgeson said. "During our initial sampling we are not finding the numbers of trout we knew were there prior to the incident. These populations fluctuate, but they are never this low."

Borgeson added there's a stretch of the river that is almost devoid of trout.

A major fish kill involving the same dam occurred in July 1984, when tons of silt swept down the river after the dam gates were opened for repairs.

Since that time, repeated requests by the DNR that the Federal Energy Regulatory Commission regulate the dam have been denied by the federal agency.

Officials from the Department of Environmental Quality's dam safety division also are investigating the incident.