A silent ecological threat is brewing
by michela sisti , contributor
I first glimpsed them from my plane window at thirty-five thousand feet. I was leaving an old home overseas and on my way to an entirely new one here in Saskatchewan. The journey could not have been more surreal or illuminating.
I watched glaciers calving off the east coast of Greenland, saw Canadian skies aglow in the dull orange haze of wildfires.
And then, as we were flying over the table-top lands of the prairies, I beheld something wonderful: a multitude of shimmering gouges in the landscape, scattered far into the horizon like so many shards of a glittering mirror.
Despite having been born and raised in Canada, I knew nothing of these mysterious water-filled depressions. There was no cultural discussion, no frame of reference I could draw from.
I didn’t know I was looking at one of the most important ecosystems on the continent. Or that these ancient water-filled kettle holes, carved out of the land by kilometre-high glaciers of the last ice age, have sustained life on the prairies for over 10,000 years.
What I had seen was a view of the Prairie Pothole region: a dynamic ecosystem of millions of variously sized wetlands extending from the southern Canadian prairie provinces to Iowa, the Dakotas, and Montana. The majority of these pothole wetlands reside right here in Saskatchewan.
Yet within our province’s borders, they are being drained and cropped over on an industrial scale. Estimates from 2001 to 2011 tell us that this ancient ecosystem is disappearing at a rate of over 10,000 hectares per year, an area equivalent to 20,000 football fields.
This number is only likely to have grown since 2011. Most of these drainage projects are unauthorized, and yet the current provincial government has done little in the way of enforcing its rules. What is more, our Water Security Agency (WSA) is now developing an Agricultural Water Stewardship Policy that will facilitate the drainage of up to 79 per cent of southern Saskatchewan’s remaining wetlands.
Let’s be clear about what we are losing. Prairie potholes are some of the most important waterfowl breeding grounds on the planet. They serve as vital migratory stopovers for so many of North America’s birds that must make the great journey from the Gulf of Mexico northwards each year.
The region also provides essential habitat for more than 50 at-risk species. In this time when insect populations around the globe are crashing, prairie potholes are precious havens for the pollinators that sustain our crops. These wetlands are also critical players in the story of climate change, storing staggering amounts of carbon in their depths and acting as mini air-conditioners on the landscape.
In a region that suffers from many water security pressures, prairie potholes are integral to sustaining our water supply well into the future. We on the prairies are prone to the extremes of drought and violent storms.
Our wetlands soak up runoff in times of heavy rain, blunting the impacts of flooding events. During dry periods, they release their water back to the atmosphere, feeding the cycle of cloud formation and rain.
They are an important site of water storage and groundwater recharge while acting as biofilters, cleaning our water supply of contaminants. A robust body of scientific literature has established that these ecosystem functions will be degraded if our wetlands continue to disappear.
Moreover, new modelling work out of the University of Saskatchewan (U of S) now allows scientists to put numbers on these losses. Dr. Colin Whitfield is an associate professor of environmental science at the U of S’s School of Environment and Sustainability. He and his colleagues have developed models to predict the effects of different levels of drainage on three metrics: water storage, water quality, and biodiversity.
Even at low levels of additional pothole drainage, the predicted blow to biodiversity is severe. “At drainage levels of 20 or 30 per cent by area, we can expect to lose about half of wetland-associated birds and a variety of dabbling duck species,” said Dr. Whitfield.
Many of these migratory waterfowl are federally protected under the Migratory Birds Convention Act (1994). Yet the highest quality habitat for these species, which are small wetlands, do not have their own protection in this province.
In fact, Saskatchewan is the only province in Canada not to have its own wetland conservation policy. According to Dr. Whitfield, these areas of high-quality habitat are usually the first targets of drainage projects as they are the easiest to do away with.
No less eye-opening are Dr. Whitfield’s findings on how drainage impacts streamflow and water storage. “When we conducted our analysis, we were showed a result that we were a little surprised by,” said Dr. Whitfield. “Even at low levels of wetland drainage, 10 per cent and up, there were notable impacts to the hydrological behaviour of these small watersheds.”
Once wetlands are drained, using a system of ditches that funnel water into lakes and rivers, they are typically filled in with earth and converted to cropland. “So, we’re losing water storage,” Dr. Whitfield explained, “We’re effectively short-circuiting the hydrologic function of the natural landscape. And that water is moving off much quicker into streams and lakes.”
In the short term, this export of water manifests itself as flooding events, so often reported on in the news, that cause damage to public infrastructure and private property. The University of Saskatchewan models support this understanding, predicting that even at low levels of additional drainage streamflow events that were once rare will become more common. In the long term, it could mean a much drier Saskatchewan in a future also impacted by climate change.
“With the certainty of warmer and the uncertainty of wetter, the precautionary principle would suggest maybe you shouldn’t drain all of the water off the surface because you don’t know if it’s coming back,” said Dr. Peter Leavitt, Canada Research Chair at the Institute of Environmental Change and Society. “Given that most farmers lose money due to excess drought the idea of getting rid of water is really kind of ridiculous.”
Dr. Leavitt lectures on freshwater ecology here at the University of Regina along with his colleague, Dr. Kerri Finlay. Both professors have expressed similar concerns about the impact continued drainage may have on our groundwater supply.
“If the water’s flowing on the surface and it’s running downhill, it’s not going down into the ground, and so you will lose your groundwater,” Dr. Leavitt explained.
Drainage also impacts water quality. At current drainage levels in the province, Saskatchewan is now at the cusp of breaching the water quality agreements that we have with our downstream neighbours, Manitoba, Montana, and North Dakota, who are at the receiving end of our rivers.
Transboundary water agreements are going to be exceeded with another 10 per cent drainage,” said Dr. Finlay, referring to a 2023 report commissioned by the WSA. In it, an arm’s length panel of experts from outside the province warned of the harms continued drainage will inflict on southern Saskatchewan’s hydrology, water quality, and wildlife.
Although the WSA has published the report on their website, their response has been disingenuous and limited to band-aid solutions. A visitor to the webpage of the WSA’s forthcoming Agricultural Water Stewardship Policy will see “Water Quantity,” “Water Quality,” and “Biodiversity and Habitat” championed as key policy goals.
Yet, aside from introducing the mitigation measure of installing reducer culverts on drainage ditches, the proposed policy is effectively a green light for wiping a vast expanse of the Prairie Pothole ecosystem off the map. According to Drs. Leavitt and Finlay, who were both invited as experts to consult on the policy, the WSA has been proposing figures ranging from 25 per cent to 79 per cent drainage of our remaining prairie wetlands. Remember that Dr. Whitfield’s modelling indicated that even 10 per cent drainage levels would have ill effects.
Dr. Leavitt’s words say it all: “The last time we had a formal interaction with [the WSA], the final question was “What proportion of wetlands can we safely drain?” And the response of the scientists, across the board, was: none. Negative. You have to put them back on the landscape. Just like they’re doing in Manitoba. Just like they’re doing in Alberta.”
In part 3 of this series, we’ll look into what provinces that do have a wetlands conservation policy are doing.
