The River Parnaíba is born in the chapada one of the Mangabeiras, of the meeting of some courses d.agua, being the Hot Water in the verge of the States of the Piauí and Maranhão, the Parnaibinha in the Maranhão, the Curriola and Lontra in the Piauí, its main confluentes. It possesss an extension of 1485 km, approximately, according to general direction South-North, divided in 3 courses: high, average and low.

In its high course, that goes of its spring (cities of Barreiras-PI, and High Parnaíba-MA) to the Estuary of the Gurguéia (municipio of Jerumenha), the river Parnaíba in such a way receives waters from the Maranhão as of the Piauí and crosses an abundant region in heaths and brooks.

In the average course, that if extends of the estuary of the Gurguéia to the estuary of the Poti (municipio of Teresina), the waters that and le receives are almost that only come from the Piauí.

                 In the low course, beyond waters piauiense and maranhenses it starts to also receive, waters of the Ceará. This stretch goes of the estuary of the Poti to the estuary of the Parnaíba (municipio Great Island).

For being one of the biggest rivers northeast, the river Parnaíba has an important partner-economic paper. This if verifies, mainly, for   the potentiality of its natural resources that propitiate aptitude for the development of innumerable activities: fishing and agropastoris, of navigability, electric energy, urban supplying, leisure, amongst others.