Seguimiento de la calidad de un embalse de abastecimiento de agua potable según las directrices de la Directiva Marco (embalse del Añarbe. Cuenca Norte)

Abstract

Monitoring of the quality of a drinking water supply reservoir according to the Water Framework Directive (A ñarbe reservoir, North basin)The Añarbe reservoir is located in the Iberic-Macaronesian region and is a water body provisionally identified as heavily modified, comparable to 'lake', that according to the "A" classification system of the WFD is "siliceous, lowlands, big and very deep", and according to the "B" system is ¨lowlands, northern, warm monomictic and of acidic waters". Two annual cycles of studies have been completed (from May of 2004 to January of 2006) looking to the main biological, physicochemical and hydromorphological parameters. The trophic state is oligotrophic for most of the parameters, except for the total phosphorus, that classifies it as mesotrophic. It does not present algal blooms and the average oxygen concentration in the hypolimnion in the zone of the dam during the stratification is 4.5 mg O 2 /l. The percentage of variation of the water volume of the reservoir respective to the maximum volume varies between 40 and 33 % for the years 2004 and 2005, respectively. It shows a good ecological potential and could be considered as a reference within its group.