The value of water and adjacent land, in environmental terms is recognised, for example in the Parc Naturel Regional de Brieres, which is dedicated to the promotion of natural species and landscapes. Water is a key part of the local quality of life that makes the region attractive to migrants whether they come to work or to retire. More recently, water availability' has been associated with tourism activity as well, and Nantes Saint-Nazaire has become an attractive place for short and medium stays and leisure. First, the rivers are constant obstacles to the circulation of goods and the mobility of people.