Water management report suggests weir on the South Saskatchewan

A report on potential storage projects suggested by Alberta’s irrigation districts suggests Medicine Hat should look at building a weir on the South Saskatchewan River to safeguard the city’s water intake system.

The report, from the Alberta Irrigation Districts Association, calls for $5 billion in major project spending on upgrades to manage water in hotter, drier summers and capture excess precipitation during the unpredictability caused by climate change.

It includes major reservoir development, but also consideration for new districts, like one proposed in Acadia, northeast of Medicine Hat, and states a weir at the Hat could mean tighter management upstream.

“A weir can be used to control water levels within (Medicine Hat) and maintain an appropriate depth for the water treatment intakes,” the report reads. “In addition, it could provide secondary benefits, which would need to be identified … It is suggested that this option be explored independently to fully assess the water security and economic potential for the City of Medicine Hat.”

Such a structure was studied locally at a high level in 2015 when the city was examining potential of bolstering tourism related to the river, but quickly shelved due to cost estimates and potential regulatory requirements.

The estimated price tag at that time was up to $50 million, while operations and maintenance might cost $200,000 per year.

The parks department determined it would be dangerous for boaters and detrimental for aquatic life, as well as require years of hydrological study and federal approval. Instead money was put toward campground and park development.

Currently, municipalities along the South Saskatchewan River have been told to review updated water management plans by Alberta Environment ahead of an expected dry spring and summer. Last year, the level at the city’s water treatment plant fell to levels considered the modern day low, as experienced in 2001. Local officials stated they experienced few operational problems, but this winter released a potential water restrictions plan that would require strict pullback on municipal and residential use if two weeks of record low flow was recorded.

Last December, the town of Leader, Sask. enacted a state of emergency to approve an emergency relocation of its water intake system as the South Saskatchewan ran lower than expected.

The irrigators report, titled Assessment of Strategic Management Projects to Support Economic Growth Final Report, also briefly touches on water supply management options for municipalities along the South Saskatchewan. It specifically states that flow levels could be ensured with a weir, allowing for tighter management of flow on the Oldman River, which supplies Lethbridge.

The South Saskatchewan River that flows through Medicine Hat is fed by both the Bow and Oldman rivers, which join northwest of Bow Island.

The Red Deer River joins the South Saskatchewan system near the Alberta boundary in Saskatchewan.

Combined, the rivers supply water to 1.8 million Albertans and about 60 per cent of the water used in Saskatchewan – which is entitled to 50 per cent of the natural flow of the river – and supplies about 600,000 residents from Lake Diefenbaker.

The province has already put money forward to study the potential to build two large reservoirs: the Eyremore Reservoir, downstream from the Bassano Dam; and the Ardley Reservoir on the Red Deer River System.

The report also calls for more storage upstream of Calgary, on the Bow, and near the headwater of the Belly River, southwest of Lethbridge.