MEDFORD, Ore. (AP) — A study commissioned by fly-fishing groups contends the effluent released from Medford's wastewater treatment plant illegally harms insect life and promotes unwanted algae growth in the Rogue River.
The study says the pollution could harm chinook salmon eggs laid in gravel downstream of the treatment plant near TouVelle State Park.
One of the study's sponsors says the city and the state Department of Environmental Quality should set a schedule for investigating and fixing the problem, the Medford Mail Tribune reported Wednesday (http://bit.ly/UeQ19m).
"Most of us would say, 'It's a sewer plant and we need to accept it,'" said John MacDiarmid of the Medford-based Rogue Flyfishers Association. "But you can't impact the beneficial uses of the river. ... They need to clean it up."
Medford Public Works Manager Cory Crebbin said the plant is operated so the released effluent is "always well within the parameters" of water-quality standards set by the DEQ permit.
Crebbin said it was premature to blame the wastewater treatment plant for changes in insect and plant life without ensuring that all other possible factors were accounted for.
"I think there must be a demonstration that the treatment plant causes or contributes to it," Crebbin said. "I believe that's an entirely open question."
The study was conducted by Rick Hafele, a retired state entomologist and fly-fishing author. It focuses on samples taken outside the "mixing zone," the area immediately downstream of a discharge pipe where wastewater can mix with river water and exceed pollution standards.
It found algae and plant growth 10 times greater downstream of the mixing zone than upstream. The extra plant life can alter dissolved oxygen and pH levels, to the possible detriment of salmon, the study said.
Underwater gravels in the upstream sites sported nine subspecies of stoneflies but just one below, "another strong indicator of water quality impairment," it said.
Information from: Mail Tribune, http://www.mailtribune.com/