The San Tirso de Abres Salmon Scale is an ecological infrastructure located on the Eo Railway Greenway, in the municipality of San Tirso de Abres. This structure allows salmon to overcome the physical barriers imposed by the dams on their migratory route to the upper reaches of the river Eo, where they reproduce. It consists of a series of interconnected steps that facilitate the ascent of the fish, contributing to the conservation of river biodiversity.

In addition to its ecological function, the salmon ladder is a point of interest on the Eo Greenway, a hiking and cycling route that follows the route of an old mining railway. Along this route, visitors can enjoy natural landscapes and observe local fauna, such as otters and waterfowl. The salmon ladder stands out as an example of environmental engineering applied to the conservation of migratory species in the river Eo.