Fishing upstream from a damn.Italo, was wondering if you could share your knowledge on the effects that damns have upstream. Will the fishing upstream from a damn be as good downstream for your typical game fish, and are certain species impacted more than others from damns?Regards,Michael

Posted on March 27th, 2017

Hi Michael,  fish are definitely “impacted” by dams since it does not allow for free fish movement in that body of water and they do change the flow above & below the dam and in some cases the water temperature below the dam. There are two type of dam structures and both have different effect on fish below and above the dam. The first one is where the flow runs over the dam (“top-discharge”, like the dams on the Grand River system. The second is where the flow is a “bottom” discharge like the dams on the Trent-Severn Waterway, Belwood Lake, Elora, ON, etc. If it’s a bottom discharge, the water is usually colder and will draw cold-water fish up to the stretches below the dam. Good example is Elora, ON where brown trout have been stocked and are thriving in the Grand River in the stretches below the dam. Down further, the water is too warm and not suitable for brown trout. Above that dam, the surface water is still warm and because it’s a “bottom-discharge”, the warm water fish like bass, walleye, pike, panfish, etc. that live and feed in the layer of water closer to the surface, won’t feel the current flow since it will be much deeper. So fishing close to the top of those dams for warm-water fish may not make any diffferance.

If it’s a top discharge, warm water fish are drawn up to below the dam, and also fish drop back from above the dam close to the dam where there is more flow in the top layers of water, and a concentration of food.

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