Cranbrook’s new source of water supply

Cranbrook’s new source of water supply

The Once and Future Dam

From 1931 to 2016 and beyond, the dam on Joseph’s Creek has served as Cranbrook’s carotid artery

Barry Coulter

Two years and $75,000 later, they were celebrating Cranbrook’s new water supply. This was in October, 1931.

“The construction of the new dam and reservoir on St. Joseph Creek … two miles from the city, marks the completion of the $75,000 undertaking for the improvement of Cranbrook’s water supply, and the assurance of of an adequate water supply of pure water not only sufficient for the present population, but for considerable expansion in years to come.”

So announced the Cranbrook Courier, Oct. 22, 1931.

Almost 85 years (and what will be $2.8 million) later, it was announced that what is old will be new again, and the dam, reservoir and what became a surrounding park will undergo a rejuvenation. The original dam and spillway itself will be subject to a complete refit. The reservoir — now know as Idlewild Lake, already drawn down — will be dredged and filled up again. And then, the forested environs will be transformed into the best park it can be, according to the wishes of the populace.

This is in large part thanks to a $2.8 million largesse from the Federal Gas Tax fund, and a further $500,000 from the Regional District of East Kootenay and Area C.

This latest announcement was made Tuesday, July 5, at Idlewild, and you can read all about it in Wednesday’s Townsman or at

Eighty five years previously, the Cranbrook Courier heralded Cranbrook’s new infrastructure centrepiece, as a long-term solution to increasing demand for water, made greater by inclement weather.

“The city originally drew its supply from St. Joseph Creek,” the Courier reported in 1931. “But … it was found necessary to bring in an additional supply from Gold Creek. This was done by the construction of an open ditch over an almost level plateau known as ‘The Summit.’”

The water supply from this ditch system proved unreliable, the Courier said, due to evaporation and seepage in summer. And the especially severe winters of 1928/29 and 1929/30 found Cranbrook seriously short of water, due to widespread use of leaving taps running to prevent freezing.

Thus, a bylaw passed during the January, 1930, allotted $75,000 to first of all construct a four and a half mile pipeline from Gold Creek over “The Summit” to a fork in St. Joseph Creek (as it was called then). Secondly, an existing dam was raised five feet, creating a storage capacity in the reservoir of 11 million gallons.

But then, a year later, in 1931 …

“After completion of the first section, it was found that sufficient funds were available to build an entirely new dam and intake works in a more suitable location 200 feet upstream from the old dam … with a present capacity of 21 million gallons.”

So that’s how much water Idlewild Lake can contain, in case you were wondering — 21 million gallons.

The 85-year-old dam consists of a “reinforced concrete core wall 20 feet high, with foundations to solid impervious hardpan varying to an additional 11 feet below the old bed of the reservoir.”

The dam is supported on both sides with earthworks, the total width at the base being 100 feet and a the crest line 20 feet.

“A concrete spillway 20-feet high with sluice gate at the bottom for emptying the reservoir completes the structure,” the Courier said in 1931.

In 2016, work on the dam will include strengthening the structure and increasing the downstream and upstream slopes. The spillway will be replaced to allow for a higher capacity flow.

The reservoir was originally designed to be dredged occasionally, but it has been decades since that was done. Silt had built up in the lake, causing water to back up onto adjacent properties.

But the drawn-down lake will now be dredged, and stocks of fish, turtles and others who call the lake home are in the process of being relocated to other suitable habitats.

The dam work is expected to be done by the end of this year, with upgrades to the surrounding park set for 2017.

Thus, Cranbrook’s infrastructure centrepiece of 1931 will resume its rightful place as Cranbrook’s carotid artery.

Back in 1931, the Courier has these final words to say:

“The full extent of the value of these improvements has already been felt by the city. During the present summer, after a year of abnormal dry seasons and very little snow, the creeks have given the lowest flow on record, but at no time has there been any danger of lack of water for domestic services and unrestricted lawn watering. For several months this summer, the city was using the entire flow of St. Joseph’s Creek, and in addition about one million gallons per day from Gold Creek.”


With thanks

to Dave Humphrey