Ms Ruth Hennessy:

On lag time, when we look at phosphorus, the lag time is generally much quicker. If that is what is causing the problem in the river, you will see the river respond and water quality improve relatively quickly. It can happen in a single growing season, so over a year, you would expect to see improvements in water quality once the sources of phosphorus are removed and the ecology will recover. For nitrogen, it will depend on the catchment and the time it takes that surplus nitrogen that is in the soil and is being leached how long it takes to work through the system. Generally, we see much of that surplus nitrogen come through within a single year and we see it come through the subsequent wet period the following winter when it will often spike.

We would expect to see the effect of it within that time. An issue in the context of lag time, particularly for nitrogen, is that we need to see improvements in a wide area across the catchment. That requires the participation of a large number of farmers across different sectors including pasture and tillage. That can cause, if one wants to call it such, a lag time in behavioural change, perhaps, or people may be slower to get on board or see their role. Widespread uptake of some of those basic measures and basic compliance and the supplementary, additional measures that can be implemented through the likes of the Farming for Water EIP and other schemes is required to see the level of water quality improve in the catchments about which the Senator spoke, such the Nore, the Suir, the Barrow and the Slaney, and elsewhere.