Devastating instream works and spread of non-native invasive species on the River Arigna

The photos below show the impact of dredging works and dispersion of non-native invasive species on the Arigna River, which is a tributary of Lough Allen in the upper Shannon catchment. We first reported these works to Inland Fisheries Ireland during 2012 and posted them on our Facebook page – shortly after these works were done, and visited the site again last week.

These works have destroyed the salmonid habitats along over 3 km of this important spawning tributary of Lough Allen and have also been polluting the lower reaches of the river with suspended solids ever since (due to the unstable banks and river bed). We also reported that these works dispersed the non-native plant species Japanese knotweed Fallopia japonica on these river banks. This plant has now aggressively taken hold all along this stretch and this river channel will never recover. Moreover, this stretch of river is now a major biosecurity threat to other areas, including downstream section of the River Arigna and Lough Allen.

The first photos below show the river at Gubharudda Bridge, Co Roscommon, in September 2011 (before the works) and then again in August 2012 (immediately after the works). It is quite clear from the 2011 photos that there was no justification for these works. There were no obstructions in this eroding river. This was an important spawning and nursery area for the brown trout population of Lough Allen.

BEFORE: Arigna River at Gubharudda Bridge, September 2011. There are clearly no blockages etc. on this channel. This was a natural upland trout stream.

AFTER: Arigna River at Gubharudda Bridge, September 2012. The aquatic and riparian habitats here have been devastated by excavation and dredging works.

Japanese knotweed growing from dispersed fragments, September 2012. There were clearly no biosecurity measures in place during these works and fragments of this non-native invasive plant were dispersed all along the section. By September 2012 new plants were growing from the dispersed fragments.

Major and unnecessary works on channel, September 2012. Hundreds of tonnes of cobble and gravel were dug from the river and piled along the banks.

Unstable banks after deranged river works, September 2012. It was clear that much of this material was destined to fall back into the river again during the first flood event.

Unstable banks after deranged river works, September 2012

Recent river excavation works, September 2012. Excavations cut into the river banks all along the section making them unstable.

Devastated stretch downstream of Gubharudda Bridge, September 2012. Did Inland Fisheries Ireland really do this?

Arigna River c 1km downstream of Gubharudda Bridge, September 2012, immediately after the dredging works.

Arigna River c 1km downstream of Gubharudda Bridge, August 2014, over 2 years after the dredging works. The non-native invasive pant species Japanese knotweed which was spread by the 2012 works is now firmly established. The banks are still unstable and this site is a source of both suspended solids pollution and Japanese knotweed to downstream catchment area.

Japanese knotweed is spreading all along the spoil heaps in this area after fragments were dispersed duing the works that took place during 2012 (photo from August 2014).

I reported these damaging works to Inland Fisheries Ireland in 2012 and offered to assist them with any prosecutions against the perpretators. However, I am still waiting for a formal reply and explanation of why no action was taken in relation to these works. Some months later I was was told verbally by IFI that they are unable to take prosecutions against persons undertaking works like this if they are completed outside the salmonid close season. They assured me that IFI was seeking to have this addressed in upcoming fisheries legislation. I never accepted that this was a satisfactory answer, but this was the one given to me by IFI. This explanation given in 2012 suggests that IFI were not involved in the above devastating dredging works on the Arigna River. However, this just does not add up when you read the below.

However were these works actually completed by Inland Fisheries Ireland?

According to this answer in March 2012 by the Minister for Communications, Energy and Natural Resources given in the Houses of Oireachtas these works actually appear to have been been undertaken by Inland Fisheries Ireland. Deputy Pat Rabbitte states “I am advised by Inland Fisheries Ireland, which is implementing this project“. According to this answer, this project cost €377,897 and was supposed to be river remedial works. We note that Inland Fisheries Ireland have never given us a proper explanation regarding why nobody was prosecuted here. Perhaps this is why? From the top photo it can be seen that there were no problems or obstructions (i.e. landslide material) in the river here in 2011, with the last recorded landslide in catchment having occurred in 2008. There appears to be no justification whatsoever for these works, and there is certainly no justification for dispersing the non-native invasive Japanese knotweed along the river corridor here. An extract from the Houses of Oireachtas answer is as follows:-

Arigna River Section — 3 km section of Arigna River at Gubharudda Bridge: This section will be undertaken in 2012 when R280 Road Bridge section is completed. The 3km section of river stretches 1km upstream of Gubharudda Bridge and 2km downstream. It is proposed to commence work on the Arigna River section in April 2012 and complete the project in October 2012. As requested, itemised costs incurred to date and estimated future costs to project completion totalling €377,897 is shown in the tables. Due to consistent debris destroying bank-work already remediated there will be ongoing maintenance works required for a period after the completion of the project.

The the full answer can be accessed here and it seems to clearly implicate Inland Fisheries Ireland in these works.

I have written again to Inland Fisheries Ireland to find out the truth about these works. The answer given me to in 2012 suggests that IFI were not involved in the above devastating works on the Arigna River. However, it is clear that this does not add up – the written answer from Deputy Rabbitte above seems to clearly implicate them in this devastation.

I have also provided this photo looking upstream from Gubharudda Bridge from September 1992. As you can see from the this photo the Arigna River looked like it did in 2011 for at least two decades prior to these works. We can see no justification for same.

Arigna River looking upstream from Gubharudda Bridge, September 1992.

After water quality, habitat destruction and invasive species are the biggest threats to riverine habitats in the Shannon catchment. It is certainly a sad day if the agency charged with protecting our aquatic habitats and, indeed supposedly taking a lead in the control of non-native non-invasive species in Ireland, end up being shown to have been responsible for these impacts on the River Arigna in Co Roscommon.

It is clear that these works would be considered to be an offence under Irish legislation

Japanese knotweed Fallopia japonica is listed as a non-native species subject to restrictions under Regulations 49 of the European Communities (Birds and Natural Habitats) Regulations (2011). This Regulation states that “Save in accordance with a licence granted under paragraph (7), any person who plants, disperses, allows or causes to disperse, spreads or otherwise causes to grow in any place specified in relation to such plant in the third column of Part 1 of the Third Schedule, any plant which is included in Part 1 of the Third Schedule, shall be guilty of an offence“. This Regulation states that “Save in accordance with a licence granted under paragraph (7), any person who plants, disperses, allows or causes to disperse, spreads or otherwise causes to grow in any place specified in relation to such plant in the third column of Part 1 of the Third Schedule, any plant which is included in Part 1 of the Third Schedule, shall be guilty of an offence”.