River Report #5 - Crops emerging as river levels trickle
A winter wheat crop gets a blast of irrigation on May 28th as growing conditions continue to be favourable in southern Alberta. (Photo Alex McCuaig)
Southern Alberta is experiencing a substantial break from agricultural drought conditions which have been the bane of farmers multiple times over the past decade heading into spring. But while cereal crop seeding is heading into the home stretch under good conditions, there is a strain on the region’s river systems.
The fortunes of both agricultural lands and rivers could both benefit from anticipated precipitation as the traditionally wettest month of the year in the is region is forecast to begin with rain during the first days of June.
Showers are expected to be heaviest in the southwestern portion of the province with 10mm possible in the Pincher Creek area starting Sunday evening going into Monday. That situation should assist in providing relief to the Oldman Reservoir which is below its normal seasonal capacity.
While surface and sub-surface soil moisture conditions continue to be overwhelmingly rated fair to good, severe hydrological drought conditions are currently being reported throughout much of the Oldman River basin.
The Bow River basin from the mountains to the forks of the Oldman is reporting moderate drought conditions along waterways.
The South Saskatchewan and Red Deer river basins are reporting adequate water supplies.
But multiple warnings are being posted across southern Alberta waterways as streamflows are failing to meet both instream objectives (IO) and water conservation objectives (WCO).
The City of Lethbridge stressed late last week in a press release while water restrictions have not been launched, conservation should be on the minds of residents. That message came into focus by Tuesday as Oldman River streamflows through the city fell below its IO of 20 metres per second (m³/s). And the end of the month has been hotter than usual with many areas in the province under a heat warning.
Lethbridge will be providing its next update on the water supply outlook on Friday.
A dry South Saskatchewan River island channel located across from the Hat’s water treatment plant. The province has issued a yellow warning regarding the river’s streamflow as it risks failing to meet instream objectives. (Photo Alex McCuaig)
The situation is unlikely to be aided by snowpack runoff from the Rockies which have peaked and are quickly running out of steam. Several mountain reporting stations are showing little to no snow left.
Regional irrigation reservoirs are in good shape but the Oldman Reservoir has been stalling in building up its capacity, a situation which could change quickly with precipitation.
The South Saskatchewan River streamflows have been running just above its IO of 42.5m³/s at Medicine Hat while falling to well below its WCO and failing to meet that objective over the last three weeks of May.
As of Thursday morning, the streamflow at Medicine Hat was 46m³/s with that rate expected to fall into the weekend. A yellow warning notification was issued for the river at the Hat early Thursday afternoon as the South Saskatchewan River nears its IO.
While the South Saskatchewan basin is reporting adequate water supply, the Oldman basin is rated at Stage 3 of the provincial five-stage drought response plan.
The trigger for that rating on the Oldman is, “with decreasing supply, the likelihood of EPA (Alberta Environment and Protected Areas) receiving a priority call from a licensee, registrant and/or household user is expected to occur.”
Stage 4 of that plan will be triggered if severe drought ratings spread across multiple water management areas which will require a regional response to the situation.
