Dr. Marie Archbold:

Basically it is about the pathway. If we think about nitrogen and the way it travels, it travels very quickly and landowners are pre-draining soils that may be overlying the areas of karst, the underground cave systems. If nitrogen gets into those areas, we will see a response very quickly. On the other side, looking at phosphorous, it usually flows overland in poorly-draining soils. After a flood or a rainfall event, one might see a response very quickly in the river, in terms of the concentrations going up. The response is based on the pathway, the soil type and the geology, as Mr. Flynn mentioned. On the response time, in terms of the chemistry, we can see it very quickly, but the response of the biology, which is another part of the assessment that is required as part of this review, can be slower. Also, it is monitored a lot less frequently, every three years. That monitoring lag is another problem. As I said, the chemical response can be very quick, but the biological response is probably the slowest to track.