Navigation
The Madeira river rises more than 15 m (50 ft) during the rainy season, and ocean vessels may ascend it to the Falls of San Antonio, near Porto Velho, Brazil, 1,070 km (660 mi) above its mouth; but in the dry months, from June to November, it is only navigable for the same distance for craft drawing about 2 m (from 5 to 6 feet) of water. The Madeira-Mamoré Railroad runs in a 365 km (227 mi) loop around the unnavigable section to Guajará-Mirim on the Mamoré River.
Two large dams (see below) are under construction as part of the IIRSA regional integration project. The dam projects include large ship-locks capable of moving ocean going vessels between the impounded reservoir and the downstream river. If the project is completed, "more than 4,000 km of waterways upstream from the dams in Brazil, Bolivia, and Peru would become navigable.".
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