Water flow in Alberta is “exceptionally low” this year and could pose a challenge for fish

Lorne Fitch, a longtime fisheries biologist and former adjunct professor at the University of Calgary, is often on a boat to view the headwaters of the Oldman River.

“It’s an interesting look at a year that doesn’t seem to follow anything resembling a normal pattern,” Fitch said.

In Alberta, June usually brings a lot of rain has not been the case this year.

Snowpacks also disappeared on average about a month earlier than in a normal year, according to Paul Christensen, a senior fisheries biologist with Alberta Environment and Protected Areas.

It has led to effects on the natural runoff cycle to which fish and insects have adapted. Low runoff isn’t always all negative, and there have been years of low flow in the past, Christensen said. But this seems to be an “exceptionally low” year.

“It’s fair to say that we’re experiencing very, very low water conditions that … I certainly haven’t seen in my career,” Christensen said.

Data available from the The Alberta government details the conditions in rivers across the county, for example in the Oldman River near Brocket, as pictured below.

Fitch explained that the hydrograph for the area shows flows that are much lower than the long-term average. It shows that peak discharges – high water in the spring – are a fraction of what can normally be expected in the spring. The trend in this year’s flow also indicates that the flood peak has receded much faster than usual, he said.

Possible consequences for fish

Fitch, the longtime fisheries biologist, said a combination of runoff – which was much lower this year, and largely over at this stage – combined with a low amount of groundwater storage, is seriously affecting summer, fall and winter flows, all of which affect trout in different ways.

“As climate change changes what was normal, we’re seeing increases in summer water temperatures, and that can lead to temperatures that are outside the tolerance level of trout, and of course mortality occurs once those temperatures are exceeded,” Fitch said.

The big question is what this means for the fish in the long run. If these conditions become a “new normal,” it would affect spring spawning trout, such as cutthroat trout that are motivated by temperature and higher currents, Fitch said.

“That could change their spawning time and affect whether the eggs laid in the gravel have the right time to mature, hatch and the small trout to hatch in time to build up enough reserves to get through a winter to come,” said Fitch.

Similarly, Fitch said trout that spawn in the fall, such as bull trout that use higher source streams to move to upperwater tributaries, could run into a fish passage problem.

“The implications are that something has changed that may be beyond the range of natural variation that these fish not only endured, but evolved with and built into their DNA over the past 12,000 years,” he said.

Christensen said he tries to be careful not to predict the future.

“Mother Nature has a constant tendency to throw a curveball at us,” he said, noting that trout populations are resilient.

“[Populations impacts are] definitely something that would be on the radar. There could be changes in runoff cycles,” he said, adding that it’s too early to say exactly what the effects might look like.

Low discharges are the biggest concern for municipalities

High River Mayor Craig Snodgrass said a number of municipalities – including Okotoks, Diamond Valley and Longview – held a meeting two weeks ago and that the number 1 topic was water, particularly the abnormally low currents.

“Hopefully the rains will continue and we can keep these streams full of water and not go too heavy on restrictions. But I can pretty much guarantee that the way we go there will be heavy restrictions later on,” Snodgrass said.

In recent years, fishing restrictions have been put in place and some river sections have been completely closed off. The province also introduced “time of day”. fishing restrictions last year.

Some of the restrictions have major implications for sporting goods stores across the province, as well as guiding operations.

“I look much more at the municipal side of things, in terms of the water restrictions we have to put in place for the city,” Snodgrass said. “But you know, those are mild inconveniences compared to shutting down your livelihood.”

The county is reminding fishermen for now to ensure that when they handle fish, it is done with extreme care, Christensen said.

“Don’t take a fish out of the water. If people want to pose for that trophy catch, keep the fish in the water, land fish real quick, give them more recovery time…it’s going to be challenging for fish,” he said.

According to Fitch, there may not be any silver bullets for this problem anytime soon. But what’s important to recognize is that trout and their survival are “inextricably linked” to conditions in the watershed, he said.

“We’ve lost some of the watershed’s absorptive properties, through things like clear-cutting, too many roads and trails, too much random camping, too much off-road vehicle activity, mining and other land-use disruptions,” Fitch said. .

“We need to start thinking about how we restore watersheds so that absorption quality is improved, so that all the moisture we get from snowfall or rainfall has a chance to stay in the headwaters and slowly melt away throughout the year.”