Dr. Marie Archbold:

On the question of upstream and downstream monitoring, the concentrations are as monitored in the water. A sample is based on what is coming downstream so it will be impacted. That sample will also show what is coming from upstream. The EPA examines land use and flow pathways that can contribute. As Mr. Flynn said, the EPA can then determine what activities are making a contribution. It can then almost decipher the relevant sources. In addition, representatives of the local authorities water programme in a large proportion of the country go out and ground truth the EPA results to further confirm the sources. There is a disaggregation involved there. We are able to pull apart the meaning of the concentrations in a sample at a monitoring point.