VIDEO: Water Security Agency opens spillway at Gardiner Dam for first time since 2020

Water roared through the spillway at the Gardiner Dam on Lake Diefenbaker on Wednesday morning.

The spillway had sat closed since 2020 due to dry conditions, but the Saskatchewan Water Security Agency said opening the spillway was necessary due to recent rainfall in Alberta and an above-normal snow pack sending plenty of water into the reservoir.

Read more:

• Increased flows prompt calls for caution near South Sask. River in coming days
• Water agency urges caution around South Sask. River ahead of Lake Diefenbaker release
• Prairie Lily riverboat resumes operations as South Sask. River rises

Opening the spillway is expected to increase the river’s flow from around 280 cubic metres per second up to about 700 cubic metres per second. The release is expected to cause the river to rise about 1.4 metres in the Moon Lake area and about 0.6 m in Saskatoon.

While the spillway was initially expected to be opened over the weekend, the agency pushed back the opening to Wednesday.

“A number of dams and reservoirs in Alberta are already full, and they’ve started to release water out of them as well, because of the rising waters,” Shawn Jaques, the agency’s president and CEO, said in an interview last week.

Water levels in the South Saskatchewan River are expected to rise following the opening of the spillway on June 10, 2026. (Mia Holowaychuk/650 CKOM)

Jaques said about 400 cubic metres of water can flow through the dam every second. At this time of year, the normal flow into Lake Diefenbaker is about 600 cubic metres per second, with typical flows through Saskatoon at about 160 cubic metres per second.

“This is significantly above,” Jaques said, “and we haven’t seen this kind of outflow since 2020.”

He said more than 1,000 cubic metres of water is flowing into Lake Diefenbaker every second, a rate that would fill Mosaic Stadium to the top in about two hours.

“We’ve been talking a lot about this this spring, because we’ve seen a lot of significant flows throughout Saskatchewan with the rapid snow melt and the heavy snow pack in the north, and we saw some of these levels of flows on much smaller rivers and channels than the Saskatchewan River, so they had quite an impact,” Jaques explained.

The Gardiner Dam spillway was opened on June 10, for the first time since 2020. (Water Security Agency)

“Residents will see a rise in the river,” Jaques said, though the City of Saskatoon noted that the increased flow rate is not high enough to cause flooding in areas along the river’s banks, like the Meewasin Valley Trail.

The rising water levels and faster flow rate prompted calls for caution around the river.

While the increased flow won’t limit recreational activities, Jaques said keeping safety in mind is always the best course of action.

“We’re cautioning and urgently urging the public to be cautious around Gardner Dam and stay away from the structure, because we are going to be flowing water over the spillway,” he shared.

“We’re also saying there’ll be an increase in flow through Saskatoon, increase in velocity on the Saskatchewan River, so we want people just to be cautious around the water at this time of year.”

The Saskatoon Fire Department is also advising extra caution as the flow rate rises.

“This represents a significant increase and with that, there’s an increase in the potential dangers on or around the river,” said fire department deputy chief Sean Thody.

Guidelines for recreational river uses shared by the city suggest that only expert paddlers with whitewater experience should head out on the water during the period of increased flow (600-800 cubic metres per second). At 800 cubic metres per second, river speeds are considered dangerous.

The fire department said it cannot put rescue divers into the water when the flow rate rises above 450 cubic metres per second due to the safety risk posed by those conditions.

The agency said it plans to release water from Lake Diefenbaker using the spillway at the Gardiner Dam, which will increase the river’s flow from around 280 cubic metres per second up to about 700 cubic metres per second. (Water Security Agency)

According to the Water Security Agency, the Gardiner Dam at 64 metres tall and, at five kilometres long, is one of the largest earthfill dams in the world.

The dam, located north of Elbow on the South Saskatchewan River, was officially opened in 1967.

The agency says the dam is operated to reduce downstream flows “thereby reducing and often eliminating flood damages to property and developments which would otherwise occur.”

Spillway makes impression on spectators

Maintenance supervisor for Douglas and Danielson Provincial Parks, Sherry Harpham, said this was the first time she has seen the spillway open.

“I didn’t really know what to expect,” she said.

“The amount of water and the force that’s actually coming out there is very impressive.”

Hapham said the spillway affects much of the province, including the docks and shorelines of the parks she maintains.

Maintenance supervisor for Douglas and Danielson Provincial Parks, Sherry Harpham, said this was the first time she has seen the spillway open on June 10, 2026. (Mia Holowaychuk/650 CKOM)

Overall, Harpham said the spillway opening will have a positive impact on the province.

“Tourists want to come and see this,” she said.

–with files from 650 CKOM’s Brent Bosker, Libby Gray and Mia Holowaychuk