No extra water required in irrigation acreage expansion, says report

Move to underground pipe and low-pressure pivots means more crop per drop

Pictured is the Snake Lake Reservoir, about 20 kilometres southeast of Bassano, as it is today. The area outlined in red shows an expansion which will add 53,000 acre-feet to the reservoir.
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The Eastern Irrigation District’s decision to expand its irrigation acres brings up a couple of questions.

Perhaps the biggest is: Where is the extra water coming from? The answer: There’s no extra water required.

According to a feasibility study conducted by the province, the 34,000-acre expansion will not require any additional draw from river sources. This is due in large part to water efficiency improvements that both the district and irrigation producers themselves have made over the past several years.

One of these has been the conversion of open canals — which lose water from both evaporation and leaks — to underground pipelines. On the farmer side, there’s been a huge investment in low-pressure pivot systems, which are significantly more efficient than high-pressure pivots and wheel move systems (and vastly more so than flood irrigation). As of 2019, low-pressure pivots were used on nearly three-quarters of the irrigated acres in the district versus less than a third in 2002.

Based on these improvements, there’s “very little additional risk” involved in increasing the allotment of irrigated acres, said district general manager Ivan Friesen.

“We feel that by (turning) our canals into pipelines as well as producers going from flood irrigation to pivot irrigation, for example, it definitely supports the fact that efficiencies are there.”

These efficiencies have helped reduce the risk of the district being unable to meet irrigation needs in a dry year, said an information package sent out to irrigators in the district. Using a theoretical 29,000-acre allotment increase, it pointed out that less water was diverted and more acres irrigated in the dry year of 2019 compared to the similarly dry year of 2000. This in turn has given the district the confidence to increase its cap on acres, the document said.

“Even in an extremely dry year diversions are within our licensed amount,” it stated. “In an extremely dry year like a 2001 we can deliver 1.5 ft./ac. to the farm gate still under our licence. If the river did not allow us to divert the required 673,000 acre-feet (ac.-ft.) and we were held to 650,000 we can draw the extra from reservoirs (23,000 ac.-ft.). If we did this three years in a row, Lake Newell, Crawling Valley and Snake Lake would only be down 25 per cent.”

Modelling shows there is a “minimal risk” of running low on water in that scenario and “with the Snake Lake Reservoir expansion, the risk remains low with an expansion to 345,000 acres.”

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