Pastaza River Basin

Global Water for Sustainability Program (GLOWS)

September 07, 2010

Mara River Basin Kenya/Tanzania

Pastaza River Basin Ecuador/Peru

Goals and Tasks

Local Partners

Wakal River Basin Rajasthan, India

Goals and TasksLocal PartnersMara Hydrological ModelMara River Basin Kenya/TanzaniaGoals and TasksLocal PartnersPastaza River Basin Ecuador/PeruGoals and TasksLocal PartnersWakal River Basin Rajasthan, India

Pastaza Basin Profile

The Pastaza River originates in the humid valleys of the eastern slopes of Ecuador’s Cordillera Central. As it descends from the Andes, it traverses remote rainforests along the border between Ecuador and Peru, flowing through one of the region’s most important petroleum producing areas and then into one of its most biodiverse wetlands complexes, the Abanico del Pastaza. These wetlands support an extremely abundant and diverse aquatic fauna that provides the main food source for several indigenous communities in the region. On the Peruvian side, the lower Pastaza basin is home to three major indigenous groups (Achuar, Kandozi, and Quechua) with roughly 21,500 inhabitants.

The mainstem Pastaza is a turbid, white-water river, but its watershed comprises a unique mixture of interconnected black and white-water systems with variable physical and chemical characteristics. This spatial heterogeneity of aquatic environments and the seasonal variation of water conditions between wet and dry periods, has helped to create extremely productive aquatic ecosystems in the Pastaza. One such ecosystem is Lake Rimachi, the largest lake in the Peruvian Amazon, located near the confluence of the Pastaza with two black water rivers, the Chuunda and Chapuri. The lake harbors a distinct assemblage of fishes and other aquatic biota.

Basin Issues

The most serious issues affecting freshwater biodiversity and the livelihoods of native communities in the lower Pastaza are environmentally unsound practices such as overfishing, illegal commercial fishing, and oil exploration and exploitation. Overfishing adversely affects several bodies of water, including Lake Rimachi, and has led to a reduction in the populations of several key aquatic species. This reduction has resulted in diminished livelihood opportunities and increased poverty in indigenous communities. The unregulated entrance of commercial fishing fleets into the Pastaza basin also threatens natural resources and the communities that depend on them. Commercial fishing interests strike informal agreements with native communities to extract large quantities of fish or purchase fish from indigenous fishermen at prices well below market value.

The Pastaza basin is the site of extensive petroleum exploration and extraction on both sides of the Ecuador/Peru border. In fact, oil extracted in the vicinity of the Pastaza River on the Peruvian side of the border amounts to 65% of all oil production in the country. Several bodies of water adjacent to petroleum activities have been polluted by spills, in some cases requiring removal and appropriate disposal of contaminated soils and severe restoration measures. The use of outdated infrastructure and technology, coupled with the government’s reluctance to impose stronger environmental regulations and the oil companies’ incomplete cooperation in observing internationally recognized environmental practices, exacerbates the problem of direct disposal of effluents into rivers and contribute to harmful pollution of bodies of water in the area. Such practices adversely affect local indigenous communities, in particular their health and livelihoods. Current Peruvian legislation permits the concession of untitled indigenous territories to petroleum companies, or other extractive industries, without proper consultation or compensation.

Quick Stats

Countries: Ecuador & Peru

Catchment Area: ~ 40,000 km2
Rainfall: 2-3 m/year, depending on location
Elevation Range: 6310 m asl (Chimborazo Volcano) to ~180 m asl

Length: ~500 km
Source: Cordillera Central of the Ecuadorian Andes
Outlet: Marañon River in Peru, tributary of the Amazon River
Main Tributaries: Huasaga River, Huitoyacu River, Bobonaza River, Capahuari River
Larger Basins: Marañon Basin, Amazon Basin

Land Uses
Humid tropical forest; Indigenous community settlements; Conservation areas: Abanico del Pastaza Ramsar Site; Petroleum concessions region: Loreto, Peru

Cultures: Kandozi: 25 communities, 2,500 inhabitants; Achuar: 65 communities, 13,000 inhabitants; Quechua: 18 communities, 6,000 inhabitants