European Eel Foundation

Xerta weir on the River Ebro, Spain, July 2024. This is the first major barrier for upstream migrating fish on this river, and it is located approximately 56 km from the sea. Construction of a new fish pass was underway at the time of my visit, with the ongoing works apparent in the video. The fish pass will be a rock ramp-type channel leading from the tailrace to above the weir. While it won’t solve all the fish passage problems at this site, it will be a significant improvement over the previous situation. Other measures being implemented at this site include fish-friendly management of the ship lock and the installation of a dedicated fish lock.

There has been a weir at this site since the 12th century. However, it was not finished until the early 15th century. The irrigation canal and boat lock were added in the 1850s, with an additional canal on the left bank constructed in the early 1900s. The 18 MW hydroelectric scheme was completed in 2002. A pool pass was installed in 2008, but it never worked effectively. This was due to the entrance being on a different channel away from the main flow in the tailrace, along with the high turbulence and flows in the pass itself.

The irrigation canals supply a vast agricultural area, including the rice paddy fields of the Ebro delta. Downstream migrating fish can still enter both the turbines and irrigation canals. However, there are plans to also address this problem in the future. It is hoped that the new fish pass will facilitate the upstream migration of , shad, and lampreys. Efforts are also underway to restore European sturgeon to the river.

The next weir upstream from here is Ascó weir, and a new rock ramp fishway has also recently been installed at this site. Further upstream, there are three major hydroelectric dams (Flix, Riba-roja, and Mequinenza). Fish passage improvements at these dams are also planned, and fish-friendly improved management of the ship lock at Flix Dam has already been implemented. However, restoring fish passage at these dams will be far more challenging.

The upper Mequinenza dam lies approximately 160 km from the sea, and historically sturgeon accessed the Ebro as far upstream as Tudela, located over 490 km from the sea. In December 2023, juvenile sturgeon were restocked into the River Ebro downstream of Xerta weir as part of the restoration project. It is hoped that the fish passage improvement works currently underway will have been successfully implemented before these fish (hopefully) return.

Restoring rivers is not easy, and there are an estimated 190 significant fish migration barriers in the River Ebro catchment, indicating the scale of the problem. The restoration efforts here are set against the background of water quality decline, over-abstraction of water, climate change, and invasive species, to name a few other pressures. But to hold on to what we still have, we have to try for the impossible.

Conditions are unlikely to ever be suitable again for sturgeon to reach Tudela, but having a small, self-sustaining population in the lower River Ebro would be a major success story. Furthermore, the fish passage improvements will greatly benefit eels, sea lampreys, and shad. These species are likely to be regularly seen upstream as far as the Flix Dam, and potentially even further into this major European catchment in the near future.

Just because you have an eel pass does not necessarily mean you are facilitating passage: Meelick Weir on the River Shannon, June 2024. Four eel passes were eventually installed on the weir to meet a planning condition that I advocated for. In my previous post, I showed that two of the "passes" were textured tiles. However, due to their placement in high flows on the old salmon pass, they could not possibly work. In this video, I show the other two passes, which are the more traditional ramp design. But these also do not work. I have checked both passes regularly since they were installed, and there is no water flowing down the ramps. There are other design flaws that limit their potential effectiveness - but it is impossible for eels to use the passes when there is no water on the ramps.

The "refurbishment" of Meelick Weir was a €3.2m project, and no other fish passage improvements were provided. This is the largest weir in Ireland, and refurbishing it presented an opportunity to address the fish passage problems. However, nothing was done, and these elver passes were recently put in as an afterthought to meet the planning condition. Despite the obvious expense, these passes were little more than a box-ticking exercise, and none of the four passes work.

The Meelick weir project is planning scandal as a different project than the one assessed in the Environmental Impact Assessment (EIA) and Natura Impact Statement (NIS) was built. The planning application stated that the original face of Meelick Weir would be "sensitively restored" to its 1880s appearance with only "vegetative growth removal and repointing" proposed. Instead, the entire historic weir was covered in concrete steps and rubble bags, and it now looks nothing like the original Victorian-era structure.

It was stated that construction access would be from the Galway bank only. However, the weir was accessed from both banks, and a "greenway" was built from Victoria Lock up to Meelick Weir through the Natura 2000 site, without planning permission. The original project proposal specifically stated that a causeway would not be built across the river to facilitate construction access. Instead, it was proposed that small sections would be dewatered and the "restoration" work would take place from floating pontoons. Careful underwater work with divers was also proposed due to the sensitivity of the site. However, a major temporary rock causeway and construction road were installed in the river, causing serious environmental impacts. The EIA/NIS also stated that there would be no dredging, yet major dredging works were undertaken during the construction phase.

It was claimed that fish passage would not be affected as this was only a restoration project. However, there were existing fish passage problems at this site, and now they have been made worse. The EIA/NIS committed to providing otter ledges, but they were never installed. The four eel passes that were reluctantly installed after the project was completed do not work. These works were all located in a dual-designated Natura 2000 site (Shannon Callows SAC/SPA). A major breach of the EU Habitats Directive and national planning laws occurred here.

Flix Dam on the River Ebro, Spain, June 2024. This dam diverts water to the Flix hydroelectric station and reduces the flow in the downstream 'Flix meander' wildlife reserve. The hydroelectric scheme was built in 1948 and does not have a fish pass. It is located 110 km upstream from the sea.

There are two large weirs (Xerta and Ascó) downstream from here, and fish passage improvements are currently underway at these weirs. A new rock ramp fishway has been installed at Ascó weir, and a new fish pass is currently being built at Xerta weir. Fish passage improvements are also planned for Flix Dam, and optimized management of the ship lock to assist fish migration is already underway. In addition to these weirs, there are two other large hydroelectric dams upstream of Flix Dam (Riba-roja and Mequinenza), making fish migration restoration on the lower 150 km of the River Ebro very challenging. Indeed, there are an estimated 190 significant dams in the River Ebro catchment.

However, eels, sea lampreys, and shad have recently been recorded as far upstream as Flix Dam, and efforts are underway to restore European sturgeon to the river and allow other migratory species to access further into this great European river catchment. European sturgeon historically accessed the Ebro as far upstream as Tudela, located over 490 km from the sea. In December 2023, juvenile sturgeon were restocked into the River Ebro downstream of Xerta weir as part of the restoration project.

In addition to fish passage problems, the River Ebro faces numerous environmental issues, most notably the historical dumping of industrial waste in Flix reservoir. Poor water quality is also evident in this video. However, water quality improvement programs are also underway, including the removal of the contaminated material from Flix reservoir.

So do textured tiles help endangered overcome human-made river obstacles? It depends on how they are installed. This is Meelick weir on the River Shannon. Four eel passes were eventually installed on the weir to meet a planning condition that I got included. Two of the “passes” are shown in this video and are examples of these textured tiles. But due to their placement in high flows on the old salmon pass, they could not possibly work. Eels are unable to use them to get upstream due to the velocity of the water flowing over the tiles, which is well beyond the swimming and climbing ability of eels (and lampreys). In my next post, I will show the other two eel passes included at this weir. These don’t work either. The “refurbishment” of this weir was a €3.2m project, and no other fish passage improvements were provided. Incredibly, a different project than the one assessed in the Environmental Impact Assessment (EIA) and Natura Impact Statement (NIS) was also built. The planning application stated that the original face of Meelick weir would be "sensitively restored" back to what it looked like in 1880 with only “vegetative growth removal and repointing”. Instead, the entire historic weir was covered in concrete steps and rubble bags, and the weir now looks nothing like the original Victorian-era structure. It was stated that construction access would be from the Galway bank only. However, the weir was accessed from this bank, and then a “greenway” was built from Victoria Lock up to Meelick weir, yet this has no planning permission. The original project proposal specifically stated that a causeway would not be built across the river to facilitate construction access. Instead, it was proposed that small sections would be dewatered and the “restoration” work would take place from floating pontoons. Careful underwater work with divers was also proposed due to the sensitivity of the site. However, instead, a major temporary rock causeway and construction road were installed in the river, causing serious environmental impacts. The EIA/NIS said there would be no dredging, yet major dredging works were undertaken during the construction phase. It was claimed that fish passage would not be affected as this was only a restoration project. However, there were existing fish passage problems at this site, and now they have been made worse. The EIA/NIS committed to providing otter ledges, but they were never installed. These works were all located in a dual designated Natura 2000 site (Shannon Callows SAC/SPA). A major breach of the EU Habitats Directive occurred here.

The ridiculous 'temporary' fish pass at Termonbarry Weir on the upper River Shannon this week. This fish pass was installed here almost 25 years ago as a temporary measure, but it never worked and was never replaced. This weir continues to block salmon and eel migration in the upper River Shannon. None of the navigation weirs along this river have adequate fish passes.

Critically endangered juvenile (Anguilla anguilla) running at Ennistymon Falls on the River Inagh, Co Clare, this week. The falls are natural - but they have been modified for hydroelectricity generation. Very few of these elvers make it upstream.