Scientists say one-third of trout eggs and young fish put into the section called the Newberg Pool grow up with distorted spines
Friday, October 20, 2000
For years, Oregonians have plucked deformed fish from the Newberg Pool in the Willamette River. Nobody could decisively say why.
Now, scientists contracted by the Oregon Department of Environmental Quality say that after stocking the pool with trout eggs and rearing baby fish, a significant number of them -- one-third -- grew up with crooked spines and, in a few cases, deformed skulls.
Observers say the study offers the most compelling evidence that the water chemistry of the pool -- a 30-mile segment of the Willamette from Newberg to Oregon City -- is to blame. But they concede more work needs to be done before declaring the mystery solved.
"The data could indicate that it could be a waterborne exposure," said Eugene Foster, toxicologist with the DEQ.
But the study's chief author, Steve Ellis of EVS Environment Consultants in Seattle, cautioned against ruling out high river temperatures and decades-long buildup of toxic contaminants along the river bottom. Few tests have been conducted on the pool's water chemistry and sediment makeup, making it impossible to pinpoint the role of upstream industrial discharges, urban and agricultural runoff and forestry practices.
Ellis' study, launched in June 1999, took 3,500 eggs from a California trout farm, fertilized them, put them in vented PVC cylinders and lowered them by cable into the river near the Newberg Boat Ramp. They were suspended 2 feet above the river bottom for more than two weeks until eyes could be seen through the eggs. Then they were removed and reared to the fry stage in laboratory aquariums.
Among the results:
• Thirty-four percent of the 372 fry sampled from the Newberg Pool showed deformities, compared with 9 percent of a control group reared in the laboratory. Previous studies show deformity rates of 5 percent or less in other segments of the Willamette, including the river's mouth, downriver from polluted Portland Harbor.
• Most of the deformities showed up in fish skeletons. But three Newberg Pool fish had deformed skulls. One photo shows a Newberg Pool fry's skeleton bent at a right angle.
Ellis also put fish in the Luckiamute River, southwest of Salem, where previous studies had found low rates of deformities. But all the trout eggs died. Ellis blamed the deaths not on contaminants but on the river's warm temperatures, which peaked at 70 degrees Fahrenheit during their hatching.
The findings were the latest in a series of $313,000 worth of studies commissioned by the 1997 Legislature to explore deformities in the Newberg Pool.
Previous studies had found skeletal deformity rates in Northern pikeminnows at 74 percent. A follow-up study last year found deformity rates had dropped but were still well above background levels. A study gauging human health risks from eating fish from the Newberg Pool is six months overdue but could be finished by year's end, DEQ officials say.
Scientists say skeletal deformities in fish may be caused by high river temperatures, low oxygen levels, genetics, parasites or lack of food -- conditions that exist in other sections of the Willamette as well, throwing some mystery over the dynamics of the Newberg Pool. The scientists suspect long-lasting toxic contaminants such as metals, pesticides and dioxin may also play a role.
But unlike previous studies, this one kept food, temperature and oxygen at equal levels once the fish were hatched and reared in the laboratory. Foster said this suggests more strongly than ever that the pool's water chemistry, influenced by the presence of pesticides and metals, affected the fry's fate.
"Because these fish came from the same brood stock, we don't think it's genetic," Foster said. "It could be something unknown. Or it could be one of these (chemical) compounds. But it doesn't look like it was temperature or dissolved oxygen, and it probably wasn't nutritional."
Observers say the findings point to the need for even more resources to pinpoint the problem.
"It's not to say that we should get alarmed," said Stan Gregory, fisheries professor at Oregon State University. "But if the environment is inducing these changes to fish, then there's a question about what it is doing to other organisms, including humans. This is not a trivial finding."
Gregory said the Department of Environmental Quality's study might underestimate the problem because trout usually deposit eggs in sediment, where they can become exposed to greater concentrations of long-lasting contaminants such as PCBs, dioxin and pesticides. "It's a strong indication that they should look further, probably at a variety of exposure surfaces," Gregory said.
Oregon Environmental Council Water Director Karen Lewotsky called on DEQ to ask legislators for more money to get to the bottom of the problem in light of the city of Wilsonville's plans to pull drinking water from the pool.
"We need to understand that, particularly if we have people drinking out of the river," she said. "We don't profess to know what the problem is. But we need to understand it.
Wilsonville Public Works Director Jeff Bauman said that water monitoring in the pool over five years at times has detected trace levels of pesticides. But no contaminants have been found at levels exceeding federal drinking water limits, even without treatment.
Still, the city incorporated granulated carbon filters and an ozone treatment system into the $47 million plant, scheduled to come on line in 2002. The additional treatments are designed to remove the same contaminants suspected of plaguing the pool's fish.
You can reach Brent Hunsberger at 503-221-8359