A new study contends that treated effluent released into the Rogue River from Medford's wastewater treatment plant illegally harms insect life and promotes unwanted algae growth — a conclusion that city officials say is premature.
Commissioned by a consortium of local, state and national fly-fishing groups, the study asserts that the effluent's impact extends close to a mile farther downstream than allowed under the city's 2011 operating permit.
The altered ecosystem not only affects desired insects that feed the Rogue's fish, it could harm chinook salmon eggs laid in gravel downstream of the treatment plant near TouVelle State Park, the study states.
Its supporters said the study, done by a former state Department of Environmental Quality entomologist and fly-fisher, shows that DEQ needs to work with the city to fix the plant's outflow, or outfall.
The city's permit provides a pollution exemption immediately below the outfall pipe, but state law requires that water quality elsewhere in the Rogue must be managed to protect designated "beneficial uses," which include fish and aquatic life.
"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, one of the study's sponsors. "But you can't impact the beneficial uses of the river.
"The DEQ and the discharger need to take responsibility for the outfall," MacDiarmid said. "They need to clean it up."
MacDiarmid said he wanted DEQ officials to respond with a time line for "investigating and correcting the problem," but he did not say how long a time line his group would accept.
Medford Public Works Manager Cory Crebbin said Tuesday that he received a copy of the study late Monday but had not yet read it. 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 plant for measured changes in plant and insect 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."
Jon Gasik, the DEQ engineer who helped write Medford's permit, said he has not read the 41-page study but forwarded it to his managers for review.
The study appears to focus on insects and plants on a specific stretch of the Rogue that DEQ's regular monitoring does not reach.
"We just got it yesterday so we don't know what we're going to do with it," Gasik said. "It'll take us some time to research it."
The study was conducted by Rick Hafele, a retired DEQ entomologist and fly-fishing author.
The study looks at insect and plant life outside the 300-foot stretch of the Rogue immediately downstream of the discharge pipe. That area is defined as the "mixing zone," or allotted space where wastewater can mix thoroughly with river flows. While the permit exempts water quality and beneficial-use standards inside the mixing zone, the permit requires that they be met outside of that zone.
Samples for the study were collected Oct. 11 and 12, 2012, amid the normal low-flow period on the upper Rogue. It focused on three riffles for sampling outside of the mixing zone — one a third of a mile upstream of the discharge pipe, another four-tenths of a mile downstream of the pipe and one 1 mile downstream from the pipe.
The study states that the heavy algae and plant growth measured 10 times higher downstream of the mixing zone than at the first riffle upstream of the discharge pipe.
Having that amount of extra plant life covers gravels favored by stoneflies and other insect nymphs and can alter dissolved oxygen and pH levels there, possibly harming salmon, the study states.
Underwater gravels in the upstream sites sported nine subspecies of stoneflies but just one on the lower site four-tenths of a mile below the outflow, showing what the study states "is another strong indicator of water quality impairment."
During the study, Hafele also observed foam from the treated effluent traveled on the surface past the mixing zone, which is not allowed under the DEQ permit, the study states.
MacDiarmid said for years he's noticed what he considered to be adverse impacts from the treated effluent on the river during fall fishing trips there. He asked the DEQ to address it when the plant's permit was under review before it was issued in December 2011.
Hafele was a guest speaker to the Rogue Flyfishers' October 2011 meeting in Medford on an unrelated presentation, and then fished with MacDiarmid in that area the following day.
"He could tell there was a problem here," MacDiarmid said.
"It doesn't meet the standards for the river," MacDiarmid said. "You don't need to be a scientist to know that. It takes a scientist like Rick Hafele to measure it."
To fund the study, Rogue Flyfishers raised $5,400 from a variety of sources, including its own coffers as well as grants from the Federation of Fly Fishers, the Oregon Council of the FFF, the Southern Oregon Fly Fishers and the Klamath Fly Casters.
Reach reporter Mark Freeman at 541-776-4470, or email at firstname.lastname@example.org.