Water flow in Alberta is 'exceptionally low' this year and could pose challenges for fish

Lorne Fitch, a longtime fisheries biologist and former adjunct professor at the University of Calgary, is often checking out the headwaters of the Oldman River. 

"It's been an interesting view of a year that doesn't seem to follow anything that resembles a normal pattern," Fitch said.

In Alberta, June typically brings high levels of rain, which hasn't been the case this year. 

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

It's led to impacts on the natural cycle of runoff, which fish and insects are adapted to. Low runoff isn't always all negative, and there have been low flow years in the past, Christensen said. But this does appear to be an "exceptionally low" year.

"It is fair to say that we are experiencing very, very low water conditions that … I certainly haven't seen in my career," Christensen said.

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

Fitch explained that the hydrograph for the area reveals flows that are much lower than the long-time average. It shows that peak flows — spring high water — are a fraction of what might normally be expected in the spring. The trend in this year's flow also indicates the flood peak has diminished much more quickly than normal, he said.

Potential implications for fish

Fitch, the longtime fisheries biologist, said a combination of runoff — which was much lower this year, and, at this stage, largely over — paired with a low amount of groundwater storage, has serious implications for summer, fall and winter flows, all of which impact trout in a variety of ways.

"As climate change changes what was normal, we're seeing increases in summer water temperatures, and that can lead to temperatures that are beyond the tolerance level of trout, and of course mortality happens once those temperatures are exceeded," Fitch said.

The big question is what this means long-term for the fish. If these conditions become a "new normal," it would influence spring spawning trout like cutthroat trout that are motivated by temperature and higher flows, Fitch said.

"That may shift their spawning times and influence whether or not the eggs that are laid in the gravels have the appropriate time to mature, hatch, and the small trout to get out in time to lay on enough reserves to get through a winter," Fitch said.

Similarly, Fitch said fall spawning trout like bull trout that use higher spring flows to move into headwater spawning 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 have not only endured but evolved with and built into their DNA over the last 12,000 years," he said.

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

"Mother Nature continually tends 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 the cycles of runoff," he said, adding it's too early to say exactly what the effects might look like.

Low flows top concern for municipalities

High River Mayor Craig Snodgrass said a number of municipalities — Okotoks, Diamond Valley and Longview among them — held a meeting two weeks ago, and the No. 1 topic was water, specifically the abnormally low flows.

"Hopefully, the rains continue and we can keep these streams full of water and we don't go too heavy on restrictions. But I can pretty much guarantee that the way we're going there's going to be heavy restrictions coming up later on," Snodgrass said.

In past years, fishing restrictions have been put in place with some river sections completely closed off. The province also implemented "time of day" angling restrictions last year.

Some restrictions have big impacts on sporting goods stores across the province, as well as guiding operations.

"I'm watching it far more on the municipal end of things, as to what water restrictions we might have to put in place for the town," Snodgrass said. "But, you know, those are mild inconveniences compared to your livelihood being shut down."

The province, for now, is reminding anglers to make sure that when they're handling fish that it's done with extreme care, Christensen said.

"Don't take fish out of the water. When people want to pose for that trophy catch, keep the fish in the water, land fish really quickly, give them more recovery time … it will be challenging for fish," he said.

There may not be any short-term silver bullets to this problem, according to Fitch. But what is important to recognize is that trout and their survival are "inextricably linked" to watershed conditions, he said.

"We've lost some of the absorptive qualities of the watershed, through things like clear-cut logging, through too many roads and trails, through too much random camping, too much off-highway vehicle activity, mining and other land use disturbances," Fitch said.

"We have to start thinking about how we restore watersheds, so that that absorptive quality is enhanced, so that whatever moisture we get from snowfall or rainfall has a chance of lingering in the headwaters and being slowly melted out throughout the year."