Pro		Con
Hydroelectric power is one of the most responsive (easy to start and stop) of any electric power generating source.1 The conversion of the forces of water to electric energy can be up to 90 percent efficient.2 Hydroelectric power produces no chemical or waste heat pollution.3 Hydroelectric power plants require little maintenance.4 Reservoir lakes can be used for recreation, and can provide considerable flood protection to downstream areas.5 Groundwater reserves are increased by recharging from reservoirs.6 Plants usually have an expected life span two to three times longer than conventional thermal power plants.7 Hydroelectric installations can be used to breed fish and other acquatic products.8		Construction costs of large-scale hydroelectric projects are high.9 Damming rivers causes changes in ecological cycles and surrounding landscapes; self-regulating ecosystems are changed into ones that must be managed.10 Sedimentation can progressively curtail a dam's ability to store water and generate energy.11 There are a limited number of feasible sites for large dams.12 Damming can cause loss of land suitable for agriculture and recreation.13 Drought can affect power production.14 Dams are vulnerable to natural forces. There is a high direct death rate from the failure of dams.15 River channels downstream from dams are more susceptible to erosion.16

AMA Commentary

Because most of the best hydroelectric sites across the U.S. have already been exploited, the growth potential of conventional large-scale hydroelectric installations is slight.17 Hydropower emits no health-threatening chemical effluents, and poses none of the dangers associated with pollutants emitted from coal- and oil-fired generating plants, and none of the dangers associated with radiation from nuclear power plants.18 Hydroelectric power installations can destroy natural habitats in the vicinities of dams and alter the ecological balance of downstream areas.19 Lakes created by dams can destroy river ecosystems and fertile bottom land, and dam collapses can kill people.20

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¹ Gabel, op. cit., p. 109.
² Sant, et al, op. cit., p. 109.
³ Gabel, op. cit.
⁴ Ibid.
⁵ Ibid.
⁶ Ibid.
⁷ Ibid.
⁸ Ibid.
⁹ Ibid. p. 110.
¹⁰ Ibid.
¹¹ Deudney & Flavin, op. cit., p. 172.
¹² Gabel, op. cit., p. 110.
¹³ Ibid.
¹⁴ Ibid.
¹⁵ Ibid.
¹⁶ Ibid.
¹⁷ Energy Security, op. cit., p. 198.
¹⁷ Daniel Deudney, Rivers of Energy: The Hydropower Potential, (Washington, D.C.: Worldwatch Institute, June 1981), No. 44, p. 5.
¹⁹ Energy in Transition, op. cit., p. 55.
²⁰ Holdren, op. cit., p. 140.