Mr. Shane Herlihy:

I thank the Senator. This morning, the EPA said a few things that I would respectfully disagree with. Before I address any of those points in particular, I will say it is important that when we look at water quality, discuss water quality and discuss data, trends and everything else, we have to think about what we are actually sampling. This comes to the heart of the issue. When we take a sample of groundwater in particular, we are taking a composite sample of things that have gone on for a very long period of time. Depending on where the sampling point is located in the aquifer, you are looking at years or decades of a composite water that you are taking a sample of. When you take a sample of that and you report it only in terms of what was there the year before, it can be difficult to draw conclusions on what has definitely occurred. That is the first point. What are we actually sampling?

There is also the issue of surface water. In the summer months and the dry months, surface water will usually reflect what is flowing into rivers and streams as groundwater, or base flow. We have less flow and it is being supported by the groundwater that is coming into those streams. In the winter months, more of what we see in the rivers comes from overland flow, where the soils are saturated and where there is intense rainfall. It runs off the surface and it picks up slurry - if it is being spread inappropriately - and other pollutants that get into the water.

Equally, wastewater treatment plants come under a lot of pressure in the winter months because they cannot cope, particularly in cases where there are combined sewers which include foul water and surface water. When they cannot cope, there has to be an outflow into the rivers. That is what is being sampled. From a hydrogeological and an environmental perspective, I have concerns with the way the EPA is reporting some of the data because it does not seem that the hydrological context is considered or portrayed in the reports. That is really important in terms of what advice you give to try to drive a policy measure that will make a difference and a change. Teagasc has done really good research.

The question of how nitrates get into the environment and into waters is really well understood, but the time-lag factor definitely does not receive enough attention in terms of how things are considered and how we respond to what we think are changes in water quality.

The second issue I have a concern about in terms of how the EPA has presented the data is that there is constant reference made to increases. The language that is being used is significant. It is being reported that there have been large increases and that concentrations are not where we need them to be. Looking at the data, the trends are quite flat. I do not agree that we are seeing any significant increases. We are generally seeing pretty stable conditions. There will always be a bit of fluctuation on the basis of natural variations and laboratory and sampling errors. One of the things that is not really discussed by the EPA in its reports is the statistics relating to how it is defining the trends it is discussing and placing huge emphasis on. Respectfully, that is a concern which needs to be addressed. The reporting shows that there are trends in terms of where the water is coming from. That is the main thing really in terms of the EPA's analysis. Perhaps Mr. Buckley or Dr. O'Connell want to comment on what we have seen today.