The Alviela river arises in the Natural Park of Serra de Aire and Candeeiros in Alcanena municipality, parish of Louriceira and flows into the right bank of the Tejo River, near Figueira Valley, in the municipality of Santarém. It has an extension of approximately 40 km and is considered one of the most polluted rivers in the country.
The pollution problem in Alviela river began with the installation of electricity plants nearby. Already in the 50s, the leather sector industries generated negative impacts on the entire river ecosystem, affecting the natural resources of the riverside villages, mills, oil mills, fishing and sand extraction. At this time, the Alviela river suffered daily discharges of 117 plants that were pouring approximately one tonne and a half of sulfides and three tonnes of chromium salts into its riverbed.
The increasing industrialization of the region and growing demand for skin by shoe factories, and the associated lack of treatment of industrial waste, created a high pollution situation that generated a climate of protests with national dimensions. In 1974 the Commission on Anti-Pollution Fight of Alviela-CLAPA in Pernes was founded, which claimed for the construction of a wastewater treatment plant (ETAR in portuguese) in the region. Since then, a wastewater treatment plant in Alcanena – where the tanning industry was concentrated - was planned and the project was approved in 1979. The construction started and was paralyzed by lack of funds, and only in December 1988 was the treatment plant inaugurated. However, increasing pollution meant that by the time it opened, the size of the wastewater treatment plant wasn´t enough for the flow to be treated.
There have been maintenance problems in the ETAR and there were new reports of fish deaths and contamination of the river Alviela. In May 2005, in an initiative of CLAPA, hundreds of people held a walk from the parish of Pernes to the source of the river Alviela in protest against pollution of the river. In the same year, an European initiative - Big Jump - promoted by the League of Nature Protection LPN- developed exhibitions and workshops along with local citizens, to alert the community to the pollution in Alviela river.
In March 2006, the Commission for the Defense of Rio Alviela, composed in 2005 by 40 entities which included the Municipalities of Santarém and Alcanena, riverside Parishes, the National Assembly deputies and NGOs, among others, held a meeting. Their mission was: the development of a detailed survey of the environmental conditions of the rio Alviela and acting as a pressure body to demand funds and the necessity of diagnosis studies to find solutions for pollution and its impacts to coastal communities. In June 2006 a petition for remediation of the Alviela river with more than 10 thousand signatures was delivered to the President of the Assembly of the Republic.
In February 2008, a study for the recovery of the Alviela river ecosystem was presented in Santarém. This study, prepared by a multidisciplinary team, and taken up by the Division of Waste and Environmental Promotion of Santarém municipality, pointed out that the source of the river pollution was in tanneries located in Alcanena and also the agriculture and cattle raising activities in Santarém municipality. In the face of these results, the study proposed the implementation of integrated treatment to deal the effluents of these industries through an association of all users and polluters of the river. The following year, the Environment Ministry made a proposal to Alcanena Chamber and industrial tanning focused on the construction of various wastewater treatment technologies and infrastructures based on the principle of "polluter pays" as a solution to Alviela's pollution problem.
In 2009, in the parish of Vaqueiros, the SOS Alviela project was developed to save native species in the river. This project focuses on training from the municipality to the local population to identify native species and report the pollution signs in Alviela during the month of September.
Finally on April 15th of 2014, the Portuguese Environment Agency-APA signed a protocol with the chambers of Alcanena and Santarém for the rehabilitation of the Wastewater Treatment System of Alcanena and Mouchão Pernes cascade. The protocol was approved by the Minister of the Environment, Land Planning and Energy. The construction will cost 14 millions Euros and should be completed by the end of 2015, under penalty of losing the EU funds.