El descuento juega un papel central y controvertido en la evaluacion de politicas en el largo y muy largo plazo: central por el peso tiene en los reultados de la evaluacion economica en escenarios intergeneracionales, y controvertido por la dificultad de reconciliar primacia del presente sobre el future, en cuanto a medio ambiente se refiere, Ello esta generando un debate cada vez mas creciente en la literature cientifica. Este trabajo cuento diferentes para tangibles e intangibles, usadas simulaneamente en el mismo Analisis Coste Beneficio. Esta metodologia es aplicada, para su contraste empirico a la evaluacion en el que se han valorado los beneficios derivados del mismo mediante una aplicacion conjunta del metodo de valoracion contigente...Discounting plays a central and controversial role in the assessment of long and very long term policies: central because of its weight on the results of economic valuation over intergenerational scenarios and controversial due to the difficulty of reconciling "sustainability" and "valuing present over future" in as far as the environment is concerned. Thus, unsurprisingly, the issue of discounting has long generated a large body of literature of hot debates. This work proposes a dual-rate discounting approach that uses simultaneously two different discount rates for tangible and intangible assets. This method was empirically tested by applying it to the economic Valuation of a Watershed Restoration Project. The benefits generated by the project were assessed through the joint application of the Contingent Valuation Method.