The intentional release of water through the Assiniboine River dikes at the Hoop and Holler Bend in Manitoba is fully underway.

"Right now, the slow release is working," Premier Greg Selinger said Saturday at about 2 p.m. CT seven hours after water began streaming through a cut in the dike and into a farm field.

The Manitoba government released a Twitter post when the process began at 7 a.m. CT. Two excavators made the cut on the east and west sides of the release point, southeast of Portage la Prairie.

"We've never had to do anything like this in Manitoba flood-fighting history so this is certainly an unprecedented move that the province is engaging in," Jay Doering, a professor of civil engineering at the University of Manitoba, said moments after the spill started.

Excavators created a 20-metre wide breach through a roadway that had doubled as a dike. The water then poured into an adjacent field, beginning the process of relieving pressure on other dikes along the swollen Assiniboine River.

The river is not expected to crest until sometime between May 18 and 20 and its flow was already at half the rate of Niagara Falls earlier this week, according to provincial officials.

Selinger was in the area, travelling by helicopter, talking to property owners and surveying the situation Saturday. He spoke to reporters Saturday afternoon and said the water was moving slower than anticipated and that the current approach — to slowly increase the amount of water moving through the cut — would be followed.

"So far it's gone as predicted. It's been a controlled release that has not done any damage," he said, talking about homes in the area. He noted that farm fields were clearly ruined by the water but added there would be compensation for that.

"Most of the properties are well-protected," he added, talking about a massive effort in the last week to shore up and build dikes around homes and communities in the path of the water.

Officials said Saturday that the amount of land that will be inundated, once the full extent of the diversion is reached, will be less than initially projected, some 180 square kilometres of land instead of 225 square kilometres.

Within a few hours, water from the cut had surrounded two homes in the area, but officials said flood protection measures were holding.

Aerial shot of controlled release point at the Hoop and Holler Bend to take pressure off the Assiniboine River dikes. Government of ManitobaThe breach is something the government hoped it would never need to do but says it had no choice.

Selinger repeated his view, based on advice from water officials, that the release will prevent an uncontrolled flood that would be much larger and affect many more people.

"This was not an easy decision," Selinger said in a brief statement aired during Friday's supper-hour newscasts.

"If we stood back and allowed nature to run its course, we would face an almost certain uncontrolled break of the dike.

"An uncontrolled break would be catastrophic and unpredictable, spilling water onto more than 500 square kilometres of land."

That spill would impact an estimated 850 homes the province has said, based on the earlier prediction of a flood covering 225 square kilometres of land.

"While it may be unprecedented, it's certainly necessary," Doering said, touring the site of the spill from a helicopter. "It will work."

Selinger has reassured residents that the water will be spread slowly and in a controlled manner. He also reiterated a promise to compensate people for any damages and lost income.

His government is dealing with record flooding along the Assiniboine River in central and western Manitoba.

It has swamped low-lying farmland, cut off roads and forced more than 1,300 people to evacuate low-lying areas in Brandon, where temporary dikes are the only thing keeping homes in the city's valley dry.

Winnipeg, to the east, is not affected.

The water from the controlled spill will initially flow at a rate of 500 cubic feet per second (cfs) — enough to fill an Olympic-sized swimming pool every three minutes — and be increased gradually every day to a maximum of 3,000 cfs.

An aerial photo shows the Assiniboine River and the Portage Diversion, which is handling 9,000 cfs more than it was originally designed to take. John Woods/Canadian Press Along the main channel of the river, the flow is expected to reach 54,000 cfs to 56,000 cfs when the peak arrives.

In the spill area, the water will pool in low-lying areas then slowly ooze over the area's grid roads, like syrup covering a waffle.

Selinger said Saturday that crews were watching the movement of water and were trying to direct it along a path that would do the least amount of damage.

"Where they see the opportunity to move the water … there will be cuts in the road to do that," he said.

It will take more than a week to cover the entire projected area. Homes that are above road grade should be OK, officials have said, while those below grade require sandbagging.

Steve Topping, the executive director of Manitoba Water Stewardship said Saturday that with the help of the military, 17 weak spots in dikes along the Assiniboine had been strengthened.

"These sites are under stress and need to be shored up," Topping said. "We are making good progress on that."

Rising Lake Manitoba

The flooded Assiniboine River has also forced up the level of Lake Manitoba, as a result of increasing amounts of water being sent there through the Portage Diversion.

Steve Ashton, the province's minister responsible for emergency measures, said a request has been made for more help from the military.

"To take some of the pressure off the critically impacted areas," Ashton said Saturday, noting people are growing tired particularly around Lake Manitoba. "Fatigue is a huge factor."

Built during a five-year span from 1965-70, the Portage Diversion provides flood protection for the City of Winnipeg and areas along the Assiniboine River.

It is designed to handle floodwater flows of up to 25,000 cfs but this year, after building up the sides, the province is squeezing 34,000 cfs through it.

As a result, the lake level is two to three feet (0.6 to 0.9 metres) above normal.

Lake Manitoba lapping at the backyard of a Twin Lakes Beach homeowner. Marjorie Dowhos/CBC

At Sandy Bay First Nation, on the western shore of Lake Manitoba, road access to critical infrastructure is being cut off by flooded roads.

Chief Irwin McIvor said access has already been lost to the lagoon the community uses to dump sewage.

They had resorted to pumping sewage into the bush before arranging with a nearby rural municipality to dump up to 10 loads of sewage into their lagoon.

"We gotta do what we can for our people at this point in time," Irwin said.

Cattle and cottagers threatened

Theresa Johnson, who lives in the Vogar area, said her home is protected by an earthen dike but much of the land is vulnerable to the flooding.

She is preparing to move about 240 head of cattle out in the next day or so but given this is calving season, it's a huge undertaking, Johnson said.

"To do it safely, to do it so there's no death-loss — or to minimize death-loss — is challenging," she said.

"Because we're talking babies, you are moving little babies — I think sometimes people think moving cattle is moving cattle but their babies have to come with them."

'We've lost at least six homes and the west beach that's closest to the diversion, the road now is underwater.'—Scott Greenlay

Some calves may not survive the journey, Johnson said.

In Delta Beach, on the south shore of the lake, cottagers are scrambling to keep up with the rising water.

Scott Greenlay said the levels is coming up "like crazy." But they are also being threatened from the backside, where water spilling out of the diversion — before reaching the lake — is spreading across the land.

"We've lost at least six homes and the west beach that's closest to the diversion, the road now is underwater," he said.

Greenlay said there are about 25 properties on the other side of the flooded road and residents are frantically working to protect the homes but they have nearly run out of sandbags and are desperate for help.

Volunteers can reach them by driving north on Tupper Street out of Portage La Prairie and following the signs to Delta.

With files from The Canadian Press