The climatological and topographical characteristics of the Iberian peninsula have made the construction of reservoirs a necessity. Thus, more than 700 reservoirs have been constructed since the beginning of the century, one hundred of which have been the object of intensive study (Margalef et al. 1976). Nevertheless, the effect of these reservoirs on rivers is practically unknown. Garcia de Jalon (1984) reached a similar conclusion in a survey of existing literature on this topic. In this study we attempt to quantify the biological and chemical effects of three reservoirs located in the middle section of the River Ter. An earlier study suggested that these reservoirs had affected the macroinvertebrate communities residing below the reservoirs (Prat 1981). Because a flood occurred during our study we were also able to monitor the regulatory efficiency of these reservoirs.

Financial support for this project was provided by the "Comisi6n Asesora de Investigaci6n Cienttfica y Tecnica" (nO 478/81).

11 páginas, 8 figuras, 4 tablas.

Peer reviewed