• The installation culminates the project to remove barriers to seasonal movements by salmon to spawn upriver and return to the sea 
  • The project includes real-time monitoring of river flow volume 
  • It was undertaken as part of an agreement between ACCIONA and the Cantabria Water Confederation

ACCIONA has installed a salmon elevator at the Palombera dam on the Nansa River (Cantabria, northern Spain) to contribute to restoring this species' natural habitat in the area. The facility, which removes barriers to the seasonal migration upriver, will enable salmon to return to their historic spawning area in Cosío. The fish will be able to return to the sea using a refurbished fishway. The project was undertaken as part of an agreement between the company and the Cantabria Water Confederation.

In addition to the elevator, the project includes two fish ladders, at the Celis and Vendul weirs, a system for real-time monitoring of the minimum compensation flow in the river, and a station for measuring and logging flow volume in the upper reaches of the river.

A conventional fish ladder approach was adopted at the Celis and Vendul weirs because the height to be scaled was small. However, because the Palombera dam is 20 metres high, it was necessary to design and build a comprehensive system to enable salmon to move upriver (elevator) and downriver (ladder).

The facilities at Palombera, Celis and Vendul together enable salmon and other fish to access 50 kilometres of waterway on the Nansa river and its tributaries. 


How the Palombera fishway works

The fish elevator is located on the right margin of the river Nansa. The salmon scale a number of artificial ponds before entering a submerged metal cabin that is then raised along system of rails to the top of the dam. At this point, the salmon can be observed, measured and documented before being released into the Palombera reservoir through a network of channels.

A structure of cascading ponds attracts the salmon to jump until they reach the elevator. The frequency at which the elevator operates is programmed on the basis of the volume of salmon swimming upriver and the point in their life cycle.

Once in the reservoir, the salmon can swim upstream using the fishways constructed at the Celis and Vendul weirs to reach their historical spawning grounds, as documented in the annals of the river, in the middle reaches of the Nansa river and its tributaries, the Lamasón and Vendul.

ACCIONA refurbished the old fish ladder, which had been unused for decades, to enable salmon fry to swim downriver from the reservoir along the Nansa to reach the Cantabrian Sea. This culminates a comprehensive system enabling young salmon to pass the Palombera dam so that they can reach the sea, mature and then return to their original spawning grounds.


Real-time data

ACCIONA has also installed a system for monitoring river conditions in real time and relaying this data. This provides the Cantabria Water Confederation with meaningful information about the river status and can provide early warning of floods. 

The system makes it possible to take action in real time so as to ensure that the minimum compensation flow is maintained.

The agreement between ACCIONA and the Cantabria Water Confederation includes a series of commitments to enhance the ecosystem on the Nansa river, where ACCIONA operates a number of hydroelectric plants, and have more detailed information about river conditions.

ACCIONA's total investment to fulfil the commitments made to the Cantabria Water Confederation amounts to €3 million. 

With these initiatives, ACCIONA is contributing to the objectives of the Cantabria Water Confederation and of the Government of Cantabria to improve the ecosystem in the Nansa river basin, and they are part of the company's commitment to protecting the biodiversity of the environments where its clean power generation facilities are located.