In the present work is studied the main discharge of the jurassic karstic aquifers located in the Cameros Chain. The discharge takes place along the main streams (Iregua, Leza, Jubera, Cidacos and Alhama) in the overthrust tectonic zone between Cameros unit and Ebro Tertiary depression; in these zones the streams are fed by groundwater (gainging streams). The mean resources measured during three hydrological years (93/ 94 to 95/ 96) were 33 hm3/year. The hydrochemical study has permitted to deduce ionic mixture processes for the discharge waters