Churchill River Diversion

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South Bay Diversion ChannelThe basin drained by the Churchill River has an area of approximately 283,350 square kilometres (km2). It lies to the north of the Nelson and Saskatchewan River basins, with its headwaters in east-central Alberta adjoining the Athabasca River drainage basin on the north and west. The river flows across Saskatchewan in an easterly direction, at an average distance of about 240 km north of the Saskatchewan River. In its lower reaches through Manitoba, it runs in a north-easterly direction, roughly parallel to and at a distance of about 160 km from the Nelson River. 

The Manitoba portion of the river has a hydroelectric potential of more than 3,000,000 kilowatts. Instead of harnessing the potential by building plants right on the river itself, part of the natural flow was diverted into the Burntwood and Nelson River system to use at the generating stations being built on the Nelson River. 

Following joint federal-provincial studies, Manitoba Hydro in February 1966 announced its intention to divert the Churchill River as part of an overall plan of northern hydro development. In December 1972, an interim licence to proceed with the diversion was issued to Manitoba Hydro by the Water Resources Branch of the Manitoba Department of Mines, Resources and Environmental Management. Construction contracts were awarded in 1973, and the diversion was in operation in 1977.

The Diversion Plan

The diversion plan centres around Southern Indian Lake, a widening in the Churchill River. There are three main components:

  1. Missi Falls Control Structure
  2. South Bay Diversion Channel
  3. Notigi Control Structure

As originally conceived, the diversion plan was to raise the level of Southern Indian Lake by 10.6 m. This "high level diversion", however, would have required that many residents of the region (including the entire community of Southern Indian Lake) to move to higher ground. Because of this, and because of environmental concerns, the plan was modified to limit the lake level rise to 3 metres.

Under the terms of the interim licence, Manitoba Hydro is permitted to divert up to 850 cubic metres per second (m3/s) from the Churchill into the Nelson. The licence also stipulates that the outflow from the control dam at Missi Falls must be at least 14 m3/s during the open water period, and 43 m3/s during the ice covered period.

Prior to development, outflows from Southern Indian Lake varied from about 566 m3/s to 1,982 m3/s with a long term average of 991 m3/s. Below the Missi Falls, tributaries bolster the Churchill natural flow to an average of 1,274 m3/s emptying into Hudson Bay. With the diversion system in operation, the Churchill flow into Hudson Bay is reduced to an average of 510 m3/s.

The diverted Churchill water is currently used at one site on the Burntwood River and at three Nelson River sites below Split Lake.

Churchill River Diversion Map

Interim Licences and Augmented Flow Program

The Churchill River Diversion Project (CRD) began operation in 1977 under an interim water power licence. The Interim Licence allowed Manitoba Hydro to divert waters of the Churchill River into the Burntwood/Nelson Rivers system and allowed for impoundment of waters on Southern Indian Lake and the Rat River. CRD has changed the flow and water level regimes of the affected areas and lakes. CRD is used for the generating stations on the Nelson River, which account for about 75% of power generation in Manitoba.

In 1986, Manitoba Hydro began operating the CRD Augmented Flow Program to optimize CRD operation. The Augmented Flow Program involves deviating from the range of water levels and flows stipulated in the Interim licence. This deviation has affected the range of lake levels on Southern Indian Lake and the releases from the Notigi Control Structure on the Burntwood River. Hydro has requested and received annual approvals for the Augmented Flow Program from the Minister of Environment, Climate and Parks. Once approved, the Augmented Flow Program forms part of the operating regime set out under the Interim Licence.

Request for Final Licence

Support Documentation

Churchill River Diversion Final Licence

Manitoba Hydro’s Churchill River Diversion Final Licence

Historical Reports