Dr. Cathal Gallagher:

I thank the Deputy. We take a catchment-level approach. I have a copy of one we have done for the River Dodder, which looks at the information. We try to bring together many sources of information along with sources from colleagues in the EPA and parks and wildlife, and we have data coming in from our own fish surveys. We also have rapid habitat assessment techniques that we use to look at habitats. We try to get a picture of the whole habitat and what is impounded. Similar to the discussion on the Shannon, we are taking a holistic approach. As we have now put dots on the map, at least we know where these barriers are and we can know how many are in a catchment.

One part of the work we are doing is prioritisation. Because we only have a limited fund, we ask where will we get the best benefit or bang for our buck. What we do is prioritisation. This is something that we are doing a little bit of research on. We are working towards further development as we engage further on the programme. The reason I say that is that this is new ground to develop a national programme. We are trying to put together all the tools in the toolbox to be able to roll it out on a wide scale. The prioritisation at present is based on looking at what the benefits are. The benefits are evaluated against the amount - the quantity - and quality of the environment that will be opened up.

In answer to the Deputy's question in relation to the overall catchment, it is also about looking at the cost - a small barrier versus a big barrier, where it might be, etc. - as well as the socioeconomic impacts and the ease of doing it.

In some cases, we have been involved for more than ten years in trying to deal with a barrier at the front of a river or close to it. If we do not get past that part, though, it does not necessarily mean we should not be doing parts elsewhere as well. It is a question of balance. These are the sorts of techniques we are using to identify and prioritise work.

There was a further prioritisation of the 257 barriers the Deputy mentioned, in that we broke them down into small, medium and large-scale. There are different scales of project. The breakdown sets out approximately 160 small-scale projects. Some of the prioritisation is driven by resources and action plans. The barrier mitigation programme has to be delivered by 2027, so we have to balance what works we can get done in that period in terms of the size of barriers. Multiple approaches have been taken.