Ecological and social implications of hydropower development on a neotropical river system, Costa Rica
Olivas, Elizabeth Anderson
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The Sarapiquí River system is one of several watersheds in Costa Rica currently undergoing rapid hydropower development. As of 2004, eight hydropower plants are in operation, one project is under construction, and additional hydropower developments are being planned for the Sarapiquí. This dissertation examined hydropower development in Sarapiquí at national, watershed, and local scales. At a national / regional scale, this study showed that partial privatization of electricity generation during the past two decades has driven hydropower development in Sarapiquí and on other Central American river systems. In Costa Rica, ~28 private hydropower plants have been constructed since 1990; six of these are located in the Sarapiquí watershed. At a watershed scale, I examined the cumulative effects of hydropower development on the hydrologic connectivity of the Sarapiquí River system. Hydropower plants have dewatered 30.9 river kilometers in Sarapiquí and roughly 10% of stream length in the watershed is now located upstream from dams. The cumulative effects of hydropower development on the ecological integrity of the watershed may interact with the effects of other human disturbances in the watershed, such as deforestation and increasing fishing pressures. On a local scale, I examined the effects of the Doña Julia Hydroelectric Center on stream fish assemblages of the upper Puerto Viejo River. The presence of a diversion dam influenced fish assemblage composition near the dam and along a dewatered reach of stream. This dissertation also examined socio-environmental conflicts associated with hydropower development in Sarapiquí. Here, I document the multiple uses of the Sarapiquí River and examine the role of hydropower as a catalyst for river conservation activities in the watershed. The case study presented in this dissertation may be applicable to other tropical watersheds currently undergoing hydropower development.