A new study suggests the health of the St. John River has improved, but it’s not all good news.
The Canadian Rivers Institute says the river is cleaner than it has been in 40 years.
The river shows improvement overall due to waste water treatment and environmental regulations that ensure less pollution.
But the institute, located at the University of New Brunswick, says other developments have changed the river and affected its variety of fish.
The Beechwood dam was built upstream in the late 1950s, and the Mactaquac hydro dam was built a decade later.
Water flows in the river now tend to be lower in the summer. Run-off from farming and forestry is also warming the water.
“What happens is you’re changing a system that was originally a cold to cool-water ecosystem, the original St. John River and what you would see upstream in the Maine north woods area,” explained Allen Curry, with the institute.
“You’re changing that to more of a warm water system, a warm water system that is lower in oxygen levels, higher in nutrient levels. In some ways it degrades the water quality to some degree.”>/p>
Changes Likely Permanent
There have also been a number of changes to the species of fish in the river.
Atlantic salmon are now endangered, since they have to be trucked up and over the Mactaquac Dam. Other native species, like the threatened striped bass, are stopped by the dam.
In addition, non-native species like pickerel have been introduced into dam headponds.
“We’re changing from what are the native brook trout and Atlantic salmon of the system,” Curry said, explaining they’re now seeing more yellow perch and chain pickerel.
Curry said introduced species like the smallmouth bass and muskellunge, which thrive in warm water and more lake-like conditions, have been spreading through the system.
He said such changes are probably permanent, so it’s time to start managing the new mix of fish in the river.
Curry noted that when the Mactaquac Dam has to be rebuilt in a few years, the plans should include some way for native species to make it upstream.
The institute hopes the research data will help decision-makers improve the river’s health further.