Tua is a river in northeastern Portugal, flowing by the border of Vila Real District and Bragança District. It is a tributary of the Douro River. The biggest and most important city it flows through is Mirandela.
The Tua line was a narrow gauge railway which closely followed the banks of the river. Construction started in 2011 on the Foz Tua Dam, which will affect the lower reaches of the river and submerge much of the trackbed of the Tua line.
There is also opposition to the dam because it will submerge the river's gorges, which has been formed after hundreds of years. In fact, after the dam starts operation it will turn the river into a lake, altering the natural state of the river.
The people of Portugal have vehemently opposed construction of hydroelectric dams on the Tua River. Even UNESCO supported the people's demands, when in May 2012, it asked the Portuguese government to cease construction of a hydroelectric dam being built at the Tua's mouth. The reason for this was that the dam threatened the Alto Douro Wine Region, a UNESCO classified area.