At the weekend we were invited to see the Severn bore in Gloucester. Although there are surges up the tidal Severn 260 times a year, on the days immediately following the new moon, the largest bores occur around the equinox.

A tidal wave starts in mid-ocean, travels toward Europe and, as the wave enters the Severn estuary, the decreasing width of the channel forces the water to form a fast-flowing wave of water travelling against the river at about 10mph.

We watched from a bend in the river at Framilode. When we arrived, we could see the river flowing out down a narrow central passage. At the due time a fast-flowing surge of water, the bore, appeared from the Bristol Channel, on this occasion making a small wave. Within five minutes thousands of litres of water had entered the river channel, which was now covered from bank to bank.

Most of us in Montgomeryshire live and farm on a tributary of the Severn. On occasions there has been too much sediment entering the river causing cloudiness in the water called turbidity – it is important that we as farmers play our part in reducing the number of times this happens. The turbidity affects organisms that are directly dependent on light, like aquatic plants, because it limits their ability to carry out photosynthesis. This, in turn, affects other organisms that depend on these plants for food and oxygen. Sediment impacts on the availability of spawning grounds for fish eggs to be laid in river gravel, with fine sediment preventing oxygen getting to the incubating eggs. As farmers we play our part in preventing water running off yards and fields by using techniques such as planting buffer strips of grass and woods to catch any run-off sediment thus reducing turbidity.

It is also important that nitrogen and phosphate do not enter rivers. Regular sampling of our soils can allow us to apply the right amount of nitrogen and phosphates making best use of our greatest asset - our soil. These nutrients, if over applied, overstimulate the growth of aquatic plants and algae blocking light and also using up dissolved oxygen as they rot. This oxygen is essential to life in the river.

Lorna Davis, NFU Cymru project manager of the Voluntary Farmer Led Approach project to nutrient management is trialling an approach to enable farmers to test nitrogen and phosphate levels in their water. This is to enable farmers to monitor land drains, ditches and streams for potential leaching off their land. For more information please contact Lorna at NFU Cymru.