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Evidence continues to point toward an aquatic bacterial disease as the cause of deaths for more than a thousand fish along the Ottawa River. Two more fish samples tested positive for columnaris yesterday, backing up preliminary results that first detected the fish-killing pathogen.
“So we are batting a thousand so far on this bacteria,” said Ministry of Natural Resources spokesman Doug Skeggs. “It is essentially quite possible that this is exactly what we are dealing with.”
Columnaris, a normal bacteria found in the river, is a contagious disease that can take hold in a fish population when their immune systems are weakened by a stressful event.
While some have pointed to this summer’s increased water temperatures as a possible stressor, Meredith Brown of environmental group the Ottawa Riverkeeper said part of the blame can be attributed human activity.
“I don’t want people to think it just stops at this bacteria killing the fish,” she said.
Ms. Brown said increased water temperatures would not explain why the fish deaths were primarily within the confines of the Cheneaux Falls Dam and the Chats Falls Dam. She points to the large Aug. 2 thunderstorm as a likely starting point of the stress event.
More than 10,000 cubic metres of untreated overflow sewage was discharged into the river that night from plants in Cobden, Pembroke, Renfew and Arnprior. Ms. Brown said that sewage combined with the stormwater run-off from farmland could have altered the river’s nutrient levels significantly enough to shock to the fish.
“Obviously, we can’t control the temperature very well on the river, but we can control the amount of nutrients that we let into the river. So our sewage treatment plants aren’t really handling the large storm events, and these events are probably only going to get worse in the future.”
She said there is even technology that can turn sewage water into drinking water, but she sees no evidence that politicians are willing to invest the necessary dollars.
Ministry of Environment officials investigated the sewage overflow incidents, but said the contaminant levels were so diluted it did not pose a health hazard.
“The plants reported normal operations and even provided by-pass information, which included chemical analysis,” said ministry spokeswoman Jackie Theoret. “That was reviewed and found to be at an acceptable level.”
Ms. Brown said reports of white foam and increased algae on the river indicate a higher level of nutrients, which sewage can cause.
A swimming advisory is still in place in the County of Renfrew, and will remain so until officials are sure there is no threat to humans.
© The Ottawa Citizen 2006