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Treatment plant scrutinized for algae growth in Rogue

Medford’s wastewater treatment plant is considered a likely — but not necessarily the only — source of nutrients that are harming water insects and causing unhealthy algae growth in the Rogue River immediately downstream of the plant’s outflow and elsewhere in the upper Rogue, a new study finds.

The study, conducted by the Department of Environmental Quality, could lead to new requirements that the plant reduce the amount of nutrients it releases into the Rogue at the plant's outflow downstream of TouVelle State Park.

The report's findings do not mean the wastewater treatment plant is violating its 2011 discharge permit, because nutrient levels were not addressed then, said DEQ senior engineer Jon Gasik, who wrote the permit.

However, the findings will lead to further studies that will look into what nutrients — such as nitrogen and phosphorus — are in the Rogue and at what levels, Gasik said. The agency also plans to study nutrient levels elsewhere in the Rogue, in water that leaves the treatment plant and other potential sources, Gasik said.

Those studies could lead to that stretch of the Rogue being listed as exceeding Clean Water Act standards for nutrients, triggering the development of a DEQ plan to get those pollutants addressed, Gasik said.

That also could lead to changes to how the plant treats its effluent before it is released into the Rogue, Gasik said.

However, the DEQ's findings are no smoking-gun proof that the plant is the cause of the pollution triggering the unhealthy algae growth and lack of micro-invertebrates downstream of the outflow, Gasik said.

"It's easy to assume that's what it is," Gasik said. "But we want to make sure. Nutrient removal is very expensive."

The stretch downstream of the plant's outflow isn't the only stretch of the upper Rogue with impaired water quality, according to the report.

DEQ crews also sampled water elsewhere in the 31-mile stretch of the upper Rogue. They discovered "nuisance algae" — thick mats of growth that harm insects and alter pH and dissolved oxygen levels, which can harm wild salmon — downstream of Cole Rivers Hatchery and elsewhere, the study states. Crews also found pH levels that exceeded Clean Water Act standards at Dodge Bridge, where Highway 234 crosses the Rogue.

The study points out the regular bloom of harmful cyanobacteria commonly called blue-green algae in Lost Creek Lake, which feeds the upper Rogue. Blue-green algae blooms elsewhere have been tied to changes in nutrient levels in the water, but no cause of Lost Creek Lake's blooms so far have been discovered.

Medford Public Works Director Cory Crebbin said he was pleased that the DEQ studied the entire upper Rogue, not just around the treatment plant, searching for other nutrient sources that might contribute to the problem.

Crebbin said the city's own study also concludes that the treatment plant outflow likely is a contributor, but not the only one.

"I've accepted that from the get-go," Crebbin said. "We want to do our part but we don't want to be the only one to do our part.

"It's the river that has the problem, not just one riffle in the river," he said.

Agency scientists also plan to look at other potential sources, such as a drainage ditch upstream of the plant's outflow and runoff from the Denman Wildlife Area, Gasik said.

The DEQ study focusing on the area around the treatment plant's outflow roughly mirrors findings of an independent study funded in 2013 by the Medford-based Rogue FlyFishers Association.

Club member John MacDiarmid said the new study shows what some of his fellow fly-fishers have believed for years — that the plant's permitted outflow was responsible for the algae growth and dearth of bugs downstream of the 100-yard "mixing zone" where the outflow legally mixes with the river.

"The people with the black hats are the DEQ," MacDiarmid said. "They're the ones who are supposed to protect water quality. Medford just needs to do what the DEQ tells them they need to do.

"A group like ours shouldn't have had to spend $5,000 to do a study to show them this," MacDiarmid said. "We have to clean this river up."

Reach reporter Mark Freeman at 541-776-4470 or mfreeman@mailtribune.com. Follow him at www.twitter.com/MTwriterFreeman.

High levels of nutrients such as nitrogen and phosphorus can encourage algae growth that's harmful to insects and fish. Mail Tribune / file photo