Major expansion of Chin Reservoir being planned

The Chin will be one of two reservoir expansions in historic 200,000-acre irrigation project

The Chin Reservoir — which is earmarked for expansion under an $815-million trilateral agreement — provides water to three irrigation districts: St. Mary, Raymond and Taber. Pictured is the Chin Reservoir where it feeds into the Stafford Reservoir.

Details of an $815-million irrigation expansion agreement are slowly trickling in.

The Chin Reservoir is one of two off-stream reservoirs to be expanded as part of adding more than 200,000 acres to the province’s 1.7 million acres of existing irrigation, an irrigation district official said.

“We’re still in the planning stages of how much we’re going to expand it,” said David Westwood, general manager of the St. Mary River Irrigation District. “We’re narrowing it down but we’re still doing some modelling and we haven’t finalized an engineering spec just yet.

“Once we decide the size, it’ll go out for detailed engineering design. I think we’re getting close — we’re just waiting on a little more information on some of the modelling we’re doing.”

The Chin Reservoir is in the St. Mary district (which stretches from Lethbridge to Medicine Hat) but also provides irrigation to the Taber and Raymond districts. Those are three of the eight districts participating in the massive expansion. Collectively, the eight are putting up 20 per cent of the funding (with the province contributing 30 per cent and the Canadian Infrastructure Bank loaning $407.5 million at a one per cent interest rate). The project will also include two new reservoirs, the province says.

The districts have been working on specifics since the project was announced last fall although this winter, the Eastern Irrigation District released plans for a fivefold expansion of the Snake Lake Reservoir. That $170-million pro­ject (most of the money is for the reservoir expansion but some is for numerous smaller modernization improvements) will provide a secure water supply for 50,000 downstream acres, primarily the east Rosemary and Duchess areas.

But most of the participating districts (the others are Bow River, Western, Lethbridge Northern and United) have not yet held plebiscites on extra irrigation allotments made possible by the boost in funding, said Westwood.

By law, each irrigation district has to hold a plebiscite among its members before allotting additional acres of irrigated land.

“We will be looking to add acres to our assessment roll, for lack of a better word, and we are looking to figure out how many acres we would like to add,” said Westwood.

Right now, the St. Mary allotment is fully subscribed, having expanded in 2011 to about 400,000 acres (from 360,000 previously).

St. Mary’s share of the irrigation expansion is forecast to be $265 million (the district also services the corridor between Lethbridge and Medicine Hat) but there are no guarantees members will approve a plebiscite. (Even the successful Easter Irrigation District plebiscite saw about 25 per cent of voting members casting a no vote.)

However, plebiscites for new allotments do not necessarily have to be done in a single shot, said Westwood.

“(Districts) may choose to go through multiple plebiscites over multiple years to get to (the point) their irrigators are comfortable,” he said. “They might have a plebiscite of, for example, a 10,000-acre allotment, go and sell those 10,000 until fully subscribed and then say, ‘We’re going to add another 10,000.’

“Maybe their ultimate goal was to add 40,000 acres but they decided to go through three or four plebiscites to get there.”

Other irrigation districts may take a different tactic such as holding a plebiscite on adding, for example, an extra 50,000 acres with the goal of selling them in a staged fashion.

“They bring them on to the market in digestible chunks at 10,000 every two or three years,” said Westwood. “Because the plebiscite is passed they can add them whenever they want.”

There’s a drawback to that method, however.

“Once exhausted they have to go back to plebiscite again if they want to add more acres.”

But adding more acres won’t require extra water.

More efficient use of water on farms is a major reason why a 200,000- acre irrigation expansion won’t require any additional water allotment. photo: St. Mary River Irrigation District

Officials say the entire 200,000-acre expansion can be done without more water allotment thanks to efficiencies at both the district level (largely through replacing open canals with underground pipes) and on farms.

“Every time we’ve had an expansion via plebiscite we’ve proven that by us doing more efficient capital works within our district plus on-farm efficiencies, we can irrigate the same amount of our current allotment with less water,” said Westwood.

“Based on that rationale we’re saying, ‘If I can do the same amount with less water, I can do more acres with the same water.’”

One of the big pluses of the $815-million project, he said, is that it accelerates these modernization efforts going ahead without as much reliance on the provincial Irrigation Rehabilitation Program — a decades-old 75-25 cost-share program between the province and the districts.

“That funding — up until fairly recently — used to be quite significant, at one point going up to $40 million annually for all the districts to share,” said Westwood. “Last year it was down in the $10-million range. Doing projects will take a very long time if using that as your primary funding source.”

It’s estimated that every kilometre of pipeline installed saves about 200 acre-feet of water but irrigation producers have also undertaken a range of water-saving practices over the years, he added.

“It’s been a transformation,” he said. “It wasn’t that long ago — I’m going to say 30 to 40 years ago although it’s still technically happening — when producers started moving away from flood irrigation which was extremely inefficient.”

One of the first moves beyond flood irrigation was the advent of wheel move systems. However, these are very labour intensive and also inefficient, said Westwood. That was followed by high-pressure pivots which consume less water, but are still not as efficient as the low-pressure pivots which are becoming standard, he said.

“Now we’re seeing a significant changeover to low-pressure pivots. We’re really seeing a cumulative positive effect on water savings just from how (farmers) are investing in their water equipment and how they’re irrigating.

“They’re very conscious of utilizing the water when they need it but not wasting it if they don’t.”

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