Water storage and retention as an alternative to drainage to manage water in Manitoba

The Weidenhamer Backflood Project just south of Deloraine: Completed in September 2011 by the Turtle Mountain Conservation District, this small dam and dike provide important flood protection to the community of Deloraine which was almost flooded in 2005.  In 2011, this project alone may have saved Deloraine from flooding.  The water was held back on 30 acres of pasture land, and after the spring runoff, when flooding of Deloraine was not longer a problem, the water was released.  The pasture has come back, and properly managed, the retention of water on this land may improve moisture levels and increase pasture yield.  This latter aspect has still to be determined over a number of years.  The Weidenhamer Project is an example of holding back water on the land to decrease flooding downstream.  It is one of the essential steps in slowing down the rate at which water comes off the land and decreasing flooding downstream.  Locally it can have an impact to decrease flooding at Deloraine.  If this kind of project were carried our in many, many more locations it would have an impact on the flooding further downstream, along the Souris River, along the Assiniboine River and on Lake Manitoba. 

The L6 Medora Creek Retention Facility: Last Tuesday, I visited this project.  Constructed in 1990, the L6 Medora Creek Retention Facility is designed to temporarily hold back 325 acre feet of water.   The sizable dam across Medora Creek (top three photos), holds back water in the valley behind the dam (bottom photo).  There is a culvert which is designed to let water out at a rate which is much less than the rate at which the valley is filled during a flood and thus enables water retention.   Holding back water in this fashion is an important step in decreasing flooding.  We need to be doing much more of this in locations where it can work effectively in southern Manitoba in order to decrease the amount of flooding along the Souris and Assiniboine Rivers and around Lake Manitoba.