With the execution of the Hydrometeorological Centralamerican Project (PHCA, 1967-1972) under the coordination of the Regional Comitee of Hydraulic Resources (CRRH) and with the sponsor of the World Meteorological Organization (WMO), supported by the United Nations Program for the Development (PNUD) was agreed to unify criteria for the trace an numbering of the main hydrographic basins in all the countries in the Central American Isthmus (Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua & Panama).

The project was developed with the purpose of assigning a nomenclature to the hydrometeorological stations, and to ease that way the processing and sharing of the information. Besides, it layed the foundations for the strengthening of the meteorological and hydrological stations that help determine the disponibility, in quantity and quality, of the surface hydric resources.

Back then, was agreed that the Atlantic slope basins were assigned odd numbers starting by basin N° 1 in Guatemala, to the 121 in Panama. In the Pacific, even numberss starting from 2 to 164.

As a result of the Central American Hydrometeorological Project, the continental and insular territory of the Republic of Panama, with an area of 75,524 Km², has been divided into 52 hydrographic basins. From these basins, 18 are in the Caribbean slope (30% of the national territory) and correspond to odd numbers starting at 87 through 121; 34 belong to the Pacific Ocean slope (70% of the national territory), with odd numbers from 100 to 166. It can be noticed that the basins areas in the Republic of Panama vary from 133.5 Km² in the Platanal river (basin N° 107) and 4,984 Km² in the Bayano River (Basin N° 148).