Lethbridge residents asked to cut water use as Oldman River keeps rising

While heavy rain has started easing in Lethbridge, a high streamflow advisory remains in place for the Oldman River.

As heavy rain begins to ease in Lethbridge, a high streamflow advisory for the Oldman River remains in place.

As of 9:30 a.m. Tuesday, the streamflow was approximately 615 m3/s.

Provincial forecasting shows the river peaking on Wednesday evening, between 750 m3/s and 1,000 m3/s.

The City of Lethbridge says while that’s higher than what has been seen in the past a few years, the flow rate is well below the threshold for overland flooding.

But still, the predicted peak may bring minor flooding to low-lying river valley parks and trails, along with added pressure to the water treatment plant.

“As of this morning, the river conditions are still pretty murky with all the rain and run off we’ve had,” said Jason Drenth, general manager of water and wastewater with the City of Lethbridge.

“Conditions are improving slightly, but we are still producing less water than demand.”

The water treatment plant produces 60 million litres of water daily, but Drenth says current conditions have meant the plant can only produce 50 million litres of water a day.

To maintain demand, the city is drawing on water from its reservoirs, while asking residents to conserve water and only use it for essential things like cooking, drinking and short showers.

“Every little drop helps for the time being,” Drenth said.

Downstream, the city’s wastewater treatment plant also continues to deal with higher-than-normal amounts of water.

“On an average day, we see about 40 million litres per day and last night we reached just over 100 million litres per day flow so that’s the additional flow just from the rain fall,” said Drenth.

With the high water and fast-moving flows expected to continue throughout the week, Lethbridge Fire and Emergency Services (LFES) is asking residents to stay away from the river.

“The instability of the riverbanks is probably one of the biggest dangers out there,” said LFES’ water rescue lead Charles Schoening.

“That’s caused both the flow in the river and the rain making the soil less stable around the riverbanks, so people need to be aware and stay back from stream banks, pond banks, everything.”

A boating advisory has been issued for the Oldman River.

While the rain is easing into Tuesday night, Schoening says the risk won’t go away overnight.

“The water, because it’s feeding in from all the tributaries and the rain may take a little longer to tamper off in the mountains, the actual high water — the crest — will happen well after the rain in Lethbridge so give it a little time for those creek banks, river banks and coulee edges to firm up as they dry out again,” he said.