Visiting the “Frieira” hydropower dam

Last friday we had the pleasure to visit the Frieira hydropower plant, the first major longitudinal barrier that anadromous fish encounter when swimming upstream the river Miño (~ 100 km), as an extension of the Passability Expert Workshop and as a part of the OSU-UVigo agreement of collaboration.

Naturgy – the company who owns the hydropower plant – invited us to see how they operated the dam and its fish ladder where many migratory species are captured and subsequently released in tributaries downstream of this major dam for an easier future downstream migration.

The fish ladder
An elevator raises fish that swam up the ladder to the top of the dam.
On this day, a trout, 2 european eels and 6 spanish nase were pulled up from the ladder.
Captured fish are then reallocated in tributaries downstream of the dam.

José Ángel Calvo presented the functionning of the hydropower plant, that works in synchrony with upstream hydropower plants, and how they manage the minimum ecological flows requierements of the river Miño. José also explained past dam removal projects and future plans to reconnect rivers by removing small and obsolete hydropower plants.

Pablo Caballero from Xunta de Galicia explained that decades ago, people noticed young eels climbing up the 30+m dam. Since then, environmental agents have been reallocating eels and other migrating species caught at the Frieira dam to tributaries of the river Miño dowstream of it, aiding in their conservation.

Then, we went to visit a recently built fish ladder in the river Deva, near Abro, as well as a recently removed weir some 250m upstream of it.