Oir

The upstream of the Sélune is inaccessible to migratory fish. They are blocked some fifteen kilometres from the sea by an impassable dam. Only two tributaries located downstream are suitable for their reproduction: the Beuvron and the Oir. The latter, with 12 km accessible to migratory fish, is the most productive spawning tributary in the network.

Monitoring activities for migratory fish are the subject of an annual presentation:

Presentations : 2018 - 2017 - 2016 - 2014 - 2013 - 2012 - 2011 - 2010 - 2005

The Oir river, which is 19.5 km long and flows east to west, has an average gradient of 11‰. It drains a catchment area of 87 km², consisting of sedimentary and metamorphic schist terrain with a few granite outcrops. The water is close to neutral and of acceptable quality, but with high nitrate levels. Human activities in this catchment are primarily agricultural (grassland, fodder crops, dairy herds).