At least some of the 656 fish found dead last month in Ashland Creek below Ashland's Wastewater Treatment Plant apparently were exposed to lethal amounts of chlorine but investigators have been unable to trace the source.
Some of the wild juvenile steelhead found dead in the creek June 24-25 showed they were exposed to up to 10 times the amount of chlorine that the state Department of Environmental Quality considers toxic to fish, reports show.
Tests and inspections since the June 24 fish kill has not pointed to the source, though no dead fish were found upstream of the plant's out-flow into Ashland Creek about one-third of a mile from its confluence with Bear Creek, according to the Oregon Department of Fish and Wildlife.
"Those levels we measured were well above those acute toxicity levels," said Dan VanDyke, the ODFW's Rogue District fish biologist who helped investigate the case.
"At least at this point, there's no obvious evidence of a release from the treatment plant," VanDyke said. "At least as it stands right now, we don't have a confirmed responsible party."
The treatment plant was initially the sole focus of the investigation into the cause of the fish kill and VanDyke said the ODFW has no other suspected sources.
Mike Morrison, the city's public-works superintendent, said his crews and DEQ officials have looked at all aspects of the plant and haven't discovered any way any toxic release came from it.
"If it came from our plant, we at this point don't know how it happened," Morrison said.
— Mark Freeman
Read more in Wednesday's Daily Tidings.