Preliminary test results have found a common bacterial disease in one of the hundreds of dead catfish found along the shores of the Ottawa River, although there's no indication yet that it's the cause of death.
Columnaris, a bacteria that enters fish through gills or the mouth, was found during tests on one of the fish that washed up on the shoreline last week.
Ministry of Natural Resources official Doug Skeggs told CBC News the result is very preliminary but added that it gives investigators something to go on. Growth of the bacteria is increased in warmer water.
Earlier, officials with the Ministry of Natural Resources said a period of warm weather at the end of July and higher than normal concentrations of algae may have contributed to the deaths of the fish.
Ontario's Ministry of Natural Resources said it's now investigating 60 kilometres of shoreline, more than double the area originally thought to be affected.
The area now extends from Chenaux Dam near Portage-du-Fort east to Constance Bay, about 15 kilometres west of Ottawa.
Don't eat fish or swim in river
Crews from Natural Resources headed back to the river on Wednesday to examine more dead catfish and collect live ones for testing.
Officials have repeated earlier warnings to residents of Renfrew County, asking them to avoid swimming in and drinking from the section of the river under investigation.
"There is nothing that we're aware of that is a concern for human health at this point," said Doug Skeggs, a spokesman with the Ministry of Natural Resources.
"Strictly as a precautionary measure, the Renfrew County health unit has advised people, while we don't know what has caused this, to not swim in the water."
Ministry officials have also warned people not to eat fish caught in the river.
Drinking water OK, city says
Meanwhile, Ottawa Public Health officials said samples taken within the city limits last week showed excellent water quality along the river. No city beaches have been closed.
A spokesperson said there is no threat to Ottawa's drinking water, which is treated after it is taken from the river.