The quality of water within Banff National Park has returned to near natural levels.
For the first time since recordings began in 1973, downstream phosphorous levels at the east end of the park are now at the same reference levels as the more pristine reaches upstream of Lake Louise.
The monitoring results are being heralded as great news, both for humans who rely on the river for drinking and recreation, but also for the smaller ecosystem of bugs, fish and algae.
Officials say the results are very significant, particularly given the tourist towns of Banff and Lake Louise release their treated effluent into the Bow River.
But, they say, multi-million dollar upgrades to wastewater treatment plants have led to a dramatic reduction in the amount of phosphorous, a nutrient that has been essentially fertilizing the river.
“Having downstream conditions similar to upstream conditions is amazing,” said Charlie Pacas, aquatics specialist for Banff National Park.
“There’s so many people that rely on the Bow, for recreation, for drinking water, for everything.”
Phosphorous is a naturally occurring nutrient and is essential for plant or algae growth in all ecosystems including rivers, but with excess phosphorous, plant and algae growth increases.
By establishing reference locations, Parks Canada and Environment Canada have jointly been monitoring water quality in Banff and Jasper National Parks since the early 1970s.
In the 1970s and 1980s, total phosphorous concentrations in the Bow River downstream of Banff were five to six times the upstream reference conditions – and continuing to increase.
But, as a result of a major upgrade to Banff’s wastewater treatment plant in the 1990s, studies revealed no further increases were observed.
Over the next decade, a 15 per cent reduction in overall phosphorous concentrations was observed, and although this was an improvement, concentrations were still higher than upstream levels.
According to the monitoring, the most recent update shows further improvements due to additional major infrastructure upgrades around 2003.
This included municipal sewage facilities at Banff and Lake Louise, as well as a change in waste handling at Parks Canada campgrounds and day use facilities.
Over the last four decades, concentrations downstream from Banff have been reduced from an average of 0.013 mg/L in the 1980s to an average of 0.011 mg/L in the 1990s.
Over the last seven years, concentrations have averaged 0.004 mg/L.
“These results are extremely dramatic and clearly show that the water has returned to natural phosphorous concentrations over the course of a single year,” said Nancy Glozier, an aquatic ecosystems scientist with Environment Canada.
The Town of Banff, which has pumped millions of dollars into upgrades to the wastewater treatment plant, welcomed the good news.
“We’re thrilled to hear this and that our waste management performance has met the park’s objectives and our own,” said Diana Waltmann, the Town of Banff’s communications manager.
“Protecting and conserving the environment is one of the Town of Banff’s, and the community’s, top priority areas.”
Glozier said keeping phosphorous concentrations at or near natural levels can help to maintain the ecosystem and food webs of the river close to natural conditions.
“With excess phosphorous, the same thing happens when someone fertilizes a lawn, and for homeowners this means more lawn cutting,” said Glozier.
“But in a river, it means more algae and larger aquatic plants. Increases in these plants and algae can also impact the amounts or kinds of other organisms living in the river – native bugs, fish and plants.”
Once phosphorous levels return to natural concentrations, researchers would expect to see a corresponding response in the algal, bug and fish communities.
Pacas said there were some very unnatural changes in the river communities of fish, bugs and algae as a result of “fertilizing the system” for decades.
Under more pristine conditions, he said, this mountain river would typically be home to more mayflies, stoneflies and caddisflies.
“In sites that are impacted, you would still see those species, but there wouldn’t be as many and they would be displaced by chironomids,” he said.
“They are all important food sources for fish and aquatic birds, but what ends up happening is they became more abundant and they’re competing for the same resources as may, caddis and stone flies.”
Pacas said the monitoring results so far are proving positive for the environment, thanks to the reduced levels of phosphorous.
“Our bug communities are back to reference conditions and our algae are very close to reference conditions,” he said.
“When you stop fertilizing grass, things may not appear as healthy at first; it takes a while for the system to re-adjust and I would assume fish communities have now also stabilized.”