Inland Fisheries

4.3.2 Man-Made Lakes

Man-made lakes are water impoundments—or water accumulated in reservoirs—that do not occur naturally in the landscape. These lakes are most commonly created by constructing dams in river or stream valleys. Water released downstream from large man-made lakes, or reservoirs, is regulated according to water use. Reservoirs are typically constructed for purposes of power generation, flood control, navigation, water supply, and recreation. Smaller man-made lakes may be constructed for agricultural irrigation, recreation, or aesthetic purposes. Since the reservoirs have both river-like and lake-like characteristics, reservoirs constitute an intermediate type of water-body between rivers and natural lakes. Their flushing rate and the degree of river influence ultimately determines the specific characteristics and potential uses of reservoirs.

A man-made lake can be designed and constructed to incorporate the desired features including, size, depth, shoreline slope, vegetation, nutrient levels, water residency time, water elevation, and water levels. A man-made lake goes through a period of equilibrium establishment (accelerated ageing) over the first few years. After that time the differences are minimal.