Yet more rain was falling along the southern Alberta-Saskatchewan border Monday, but officials said water levels were lower than expected after three days of rain led to heavy flooding.

Environment Canada forecast up to 30 millimetres of rain for parts of southern Alberta Monday, including in Medicine Hat, where hundreds of residents have already been evacuated due to prior flooding.

Medicine Hat Fire Chief Ron Robinson told reporters Monday the swollen South Saskatchewan River "is flowing lower than was anticipated, so we don't believe that the same impact will occur as was experienced this weekend."

CTV Calgary's Kevin Rich reported that 600 homes are still under an evacuation alert, while another 230 homes are on evacuation notice.

"The overriding concern right now is outside of Medicine Hat … A lot of the rural areas are totally underwater. Some are under two feet of moisture," Rich reported Monday from the city.

Rob Renner, Alberta's environment minister, said irrigation canals are completely underwater, as are fields of crops, which will be devastating to local farmers.

"Those simply are not going to be replanted," Renner said. "So there's huge impact, not only on the infrastructure … but clearly the crops that are underwater right now are not likely to be harvested this fall and there's no time to re-seed."

The normally arid Medicine Hat has received 150 millimetres of rain since Friday. The rain has closed the Trans-Canada Highway between Medicine Hat and Maple Creek, Sask., and it is unclear when it will reopen.

Despite the grim news, residents will have some relief Tuesday, as rains are expected to taper off and move into Saskatchewan, for which Environment Canada has issued severe thunderstorm warnings. The agency also issued tornado watches for parts of south-central Saskatchewan Monday afternoon.

Earlier Monday Barry Rudd, the mayor of Maple Creek, said people in the town of 2,600 were in clean-up mode, after streets in the town were filled with torrents of water.

"Basements being pumped out, there's furniture all over the lawns, people are hauling stuff out to the dump," he told CTV News Channel Monday afternoon.

"The water is all gone but we still have people evacuated in some of the worst areas in town, and they probably won't be back in for some time," he said.

He says though more rain is forecast for his town, "I don't think we're going to get anything like we've had."

Saskatchewan Premier Brad Wall toured the area around Maple Creek and said the damage is extensive. Wall said it's "a major disaster" for the town and the province will move as quickly as possible to provide financial aid to help residents recover.

Officials believe the recent damage to local roadways and bridges is likely in the range of millions of dollars.

With files from The Canadian Press