Pastaza River

The Pastaza River ( es, Río Pastaza, formerly known as the SumataraEnock, Charles Reginald (1914) ''Ecuador: its ancient and modern history, topography and natural resources, industries and social development'' Charles Scribner's sons, New York
pages 177–178
) is a large tributary to the Marañón River in the northwestern Amazon Basin of South America.Ziesler, R. and G.D. Ardizzone, G.D. (1979
"Amazon System"
''Las Aguas Continentales de America Latina / The Inland Waters of Latin America'' (COPESCAL Technical Paper No. 1) Fisheries and Aquaculture Department, Food and Agriculture Organization of the United Nations (FAO), Rome, , in English and Spanish

It has its headwaters in the Ecuadorian province of Cotapaxi, flowing off the northwestern slopes of the volcano Cotopaxi and known as the Patate River. The Patate flows south and in Tungurahua Province it is joined by the Chambo River just upstream from the town of Baños de Agua Santa just north of the volcano Mount Tungurahua and becomes the Pastaza.Topographic ma
Baños, Ecuador, Series J721, Sheet 3989 IV, 1:50,000
Instituto Geográfico Militar (IGM), Quito, Ecuador, September 2000, reprinted by the U.S. National Imagery and Mapping Agency Seven kilometers east of Baños, it is dammed for the Agoyán hydroelectric project, which has created a silty lagoon by the village of La Cieniga. The Agoyán dam was placed in that location specifically to leave the famous Falls of Agoyán, about 5 km further downstream, intact. After the waterfall the river enters a gorge where there is very fast whitewater with class-4 rapids; it is often used for whitewater rafting although it is not considered to be of the same quality as the Tena River and is therefore less popular for the sport.

From the junction with the Chambo, the Pastaza flows almost due east for about where it then turns south-east, as it is joined by the Topo River.Topographic ma
Rio Negro, Ecuador, Series J721, Sheet 3990 II, 1:50,000
Instituto Geográfico Militar (IGM), Quito, Ecuador, June 1996, reprinted by the U.S. National Imagery and Mapping Agency The Troncal Amazonas highway parallels the river from Baños to Puyo, passing through seven tunnels, and four major waterfalls that are touristic destinations for many Ecuadorians (Agoyán and Pailón del Diablo being the most popular.) Just past the town of Santa Inez, the Pastaza River crosses into the province of Pastaza, where it forms the boundary between that province and Morona-Santiago. At the town of Mera, shortly before reaching Puyo, the river exits the mountains and flows into a wide valley, becoming wider and shallower.Topographic map Mera, Ecuador, Series J721, Sheet 3989-I, 1:50,000, Instituto Geográfico Militar (IGM), Quito, Ecuador, 1989, a reduced image is available from IGM
After Shell the river becomes braided and meanders, leaving oxbows and sloughs along its route across the Amazonian floodplain.

After cutting through Ecuador, the Pastaza passes into Peru at the village of Hito Zoilaluz on Isla ZoilaluzTopographic ma
Checherta, Peru, Series J632, Sheet 1565, 1:100,000
Instituto Geografico Nacional (IGN), Lima, Peru, June 1995, reprinted by the U.S. National Imagery and Mapping Agency and flows south into the Marañón River near Puerto Industrial.Topographic ma
San Isidro, Peru, Series J632, Sheet 1661, 1:100,000
Instituto Geografico Nacional (IGN), Lima, Peru, October 1993, reprinted by the U.S. National Imagery and Mapping Agency

Tributaries

The Pastaza has numerous tributaries, both above and below the hydroelectric dam. These contribute to its rapid flow and to its tendency to flood. On the highway side of the Pastaza, a tributary river occurs about every 3–4 km for a stretch of about 50 km; on the opposite bank, the number of tributaries is slightly lower. The major tributaries are the Chambo, Bobonaza, and Huasaga, also important are the Ambato, the Pindo, and the Puyo.

Economy

There are no major fisheries on the Pastaza River - it is primarily used as a means of transport by canoe. Its rise and fall are rapid and uncertain, and it is shallow and full of sandbanks and snags. Flooding occurs seasonally.

Bridges

In Ecuador, there are very few bridges across the Pastaza. The most significant ones are in Tungurahua province - namely a large span over the exact point of headwaters, just north of Baños, and the secondary span created by the Agoyán dam. After this, bridges tend to be of the suspension type, suitable for foot or small vehicle passage only. However, it is notable that the Pastaza can be forded during the dry season in a 4x4 truck, going across the floodplains below the town of Mera.

See also

* Agoyán

References and notes

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Tributaries of the Amazon River
Rivers of Ecuador
Rivers of Peru
International rivers of South America
Ramsar sites in Peru
Upper Amazon
Rivers of Loreto Region