[en] The El Palmar National Park located in the El Palmar Basin (Entre Ríos, Argentina) is a natural reserve of a relictic nature. As a protected area, its importance lies in the population of Yatay palm trees (Butia yatay). This type of palm tree is restricted to the area of the national park and its surroundings and it is uncommon to observe them in other locations on the platense coast. In the area there are outcrops of units of Cretaceous age represented by the Puerto Yeruá formation on which were deposited the clastic sediments of the Salto Chico formation of Plio-Pleistocene age (no outcrops) and the Ubajay formation of Holocene age in net contact. We identified two types of aquifers in the area, one fissured aquifer contained in Puerto Yeruá and two clastic aquifers contained in the Salto Chico and Ubajay formations. The first is of very thin and low permeability and the second of comparable permeability but thicker. The proposed hydrostratigraphic model has allowed us to understand the lateral and vertical variations of the aquifer units involved.