Myth: Hydroelectric dams damage river ecosystems

All dams change river ecosystems, not just the small percent that produce electricity. These new ecosystems are not 'unhealthy', just different. The change can be viewed as positive or negative based on value judgements. It is necessary to evaluate each project individually, using sound science and without preconceived bias or prejudice.

The reservoirs behind dams are often teeming with life, including both anadromous fish and the resident fish populations that depend on the reservoir for survival. These dams provide more bio-diversity, not less. Anglers place great value on these lakes because they often provide blue-ribbon fisheries. Wildlife preserves are often created around reservoirs which, in some cases, provide stable habitats for endangered or threatened species.

Most hydropower projects are 'run-of-river' and do not have the extreme downstream effects mentioned. Often, 'peaking plants' that store and release water, can benefit downstream riverine systems. For instance they may raise dissolved oxygen levels, control water temperatures, or provide increased recreational opportunities. Those storage projects whose effects are not so benign can be managed to lessen their impact.

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