The Inter-Mountain Watershed district has been researching water retention strategies and has come up with the idea of dry dams.
The need for dry dams are due to the steep slopes next to the Riding Mountains and the Duck Mountains. This creates high water velocities and high water erosion potentials (Thiele, 2019).

Within the Watershed district there are some of the steepest slopes in Manitoba, major rivers with multiple water issues, and headwaters in the Duck and Riding Mountains. All of these rivers and tributaries are leading into Dauphin lake and are increasing the pressure being put on the lake as well as the landowners around the area.
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The Goal
The goal for the Inter-Mountain Watershed District is to reduce the flows up to 10% by implementing dry dams which will reduce negative impacts and flooding downstream. 

What is a Dry Dam? 

A dry dam is a structure that does not hold water year round, however is designed to retain it for about two weeks. The dam has an undersized culvert pipe that is installed through it to restrict water flow during spring run off and large storms.

What are they designed to do? 

“What they are designed to do is, to take off that peak flow when we have a real high runoff event, whether it’s a spring snow melt. Or a summer storm. Usually we get one or two per summer” “So it is going to take off the high peak flow that does flooding and erosion damage” (Thiele, 2019).

Benefits of Dry dams

  • Flood Control
  • Erosion Control
  • Regulate peak flows
  • Nutrient reductions of nitrates and phosphorus
  • Some can provide back-flood irrigation and a livestock water source

Frequently asked questions

How much land will be taken up? 
The amount of land being taken up or used by the dry dam depends on the size and design of the dry dam. This can be discussed with the District. 
What is the average cost of a dry dam? 
​Every dry dam structure is different and has different design requirements therefore they can be as high as $50,000. Fortunately, there are grants and programs that can be applied for which can help cover costs.
What is the average timespan for the dry dam to be built? 
The average timespan for a dry dam varies on different conditions such as weather, availability of contractors, funding approval, and all the work prior to be done.
What does water retention mean?
Water retention is known as retaining water on the land so it reduces flow downstream and protects from flooding and erosion. In this case we are constructing dry dams as a water retention strategy in the Watershed district.
Picture
Dry dams are built along tributaries. Above is a map of the tributaries located within the district.