Posted on: May 18, 2022 | Water Levels
Manitoba Transportation and Infrastructure has provided the following response to explain the facts and limitations of managing the levels in West Hawk and Caddy during the unprecedented weather we have all experienced.
SENT ON BEHALF OF FISAHA UNDUCHE.
Thank you for your email expressing your concerns regarding the high water level on West Hawk Lake. As you most likely know, most southern and central Manitoba basins, including the Whiteshell Lakes Area, have been receiving a significant amount of precipitation since April 1st. Specifically, the Whiteshell Lakes basin has received record amount of precipitation since April 1st (highest ever recorded since 1951, see chart below). This precipitation came on top very high amount of snow accumulation between November and March. Due to this heavy winter and spring precipitation, there is significant runoff happening in all southern and central basins, which has led to above normal water levels on lakes and rivers. The West Hawk Lake system has received some of the heaviest precipitation and therefore we have seen record amounts of inflow coming into the system. The level rise on West Hawk Lake is mainly as a result of this heavy inflow into the lake.
As you probably know, West Hawk Lake drains to Caddy Lake, which in turn drains to South and North Cross Lakes. The outflow from West Hawk Lake is regulated by a stop log control structure whereas the outflow from Caddy Lake is restricted by tunnel crossings at the downstream end and two fixed weirs at the outlet of North Cross Lake. Every removal of a stop log at West Hawk Lake increases levels on Caddy Lake. To give you a perspective, for a log operation that would lead to a drop in one inch of the level, the Caddy Lake level would rise by about 3 inches due to its limited volume. So far, we have been doing a daily water level management in order to balance the impact of the high water level on West Hawk and Caddy Lake. For your information, we have been receiving significant amounts of concerns from Caddy Lake residents indicating they have been adversely impacted by the opening of the logs at West Hawk Dam. Unfortunately, with the heavy inflow coming into the lakes, there is a limited amount of room we can play with to reduce the impact on both lakes.
While it may seem that West Hawk has been rising unfairly in recent days, please keep in mind the entire timeline. During the early rain events we kept West Hawk flowing openly and this caused a rapid rise in the Caddy Lake levels. We operated in this manner in order to get as much water as possible out of the system as early as possible as the higher the level on Caddy is, the higher the outflow that can be achieved through the tunnels. For reference – between April 22 and May 6, Caddy Lake rose by 56 inches whereas West Hawk Lake rose by 27 inches in that same span. Our goal was to get the Caddy Lake level up close to the roadway at PR 312 and then insert logs into the dam to keep it there to maintain the high outflow. At this point West Hawk would begin to take on its share of the burden as we attempt this delicate balancing act to reduce the maximum damage to properties between the two lakes. In early May the water started rising above the roadway so we inserted 5 logs into the dam at that time. Since May 6, Caddy has risen by 6 inches and West Hawk has risen by 18 inches. Currently both lakes are similarly affected by this extraordinary weather pattern and we will continue to operate in order to try to limit damages the best we can for everyone.
As you probably noticed, both lakes have nearly crested from whatever inflow the basin has produced. However, in unfortunate news, there is another significant precipitation event in the forecast that is going to impact the Whiteshell Lakes area that could bring anywhere between 40 mm and 70 mm rain in the next 7 days. In the anticipation of this significant rain, we asked our operation crew at the site to remove one log from West Hawk Lake in order to limit the further rise on the level due to the rain. This operation was completed around 11:30 this morning and we will be monitoring the effects of the operation very closely over the next 24 hours. You will notice this operation will lower the level on West Hawk slightly but will start to increase the level on Caddy Lake. At some point in the coming days/weeks, we may be forced to insert the log back into the dam in order to limit the rise on Caddy Lake.
It is unfortunate to see the damages happening at these lakes, including at your property. However, I hope you understand the complex situation we are going through in dealing with Mother Nature.
Hope this answers your questions.