I recently spent the day with the Wye and Usk Foundation and other members of Rivers Trusts from across the country looking at the conservation work they are doing to restore the Wye, the Usk and their tributaries back to good health.
Rivers Trusts have been formed by angling groups, riparian owners and conservationists to ensure the survival of our rivers. Initially tasked with restoring fish stocks it soon became clear that the whole river systems have to be restored to good health to ensure the fish survive and multiple. The trusts are funded with private money and European funding and work in partnership with government bodies.
Thursday’s visit took us to see two important aspects of their work on tributaries of the river Wye. The principles of what we saw are and can be applied to the Usk and rivers across the country.
All rivers start somewhere up in the hills. The grassy, peaty uplands act like gigantic sponges soaking up rainwater and releasing the water steadily throughout the year to ensure an even flow and preventing flooding. This is all well and good until the Forestry Commission come along and plant conifers on the uplands. This has two major effects;
(1.)The foresters dig ditches in the bogs to drain them which cancels out the sponge-slow release effect and (2.)conifers make the water too acidic. If the water is acidic young fish will not survive when they hatch.
Up on the hill we saw how the Wye and Usk foundation had negotiated with the foresters not to re-plant the main bogs once the trees had been felled and had also dammed up the drainage ditches. It had only taken a few months for the drains to begin to silt up and the ground return to its original sponge like status.
The second step is increasing the pH of the water so that young salmon and trout will survive. This has been done by spreading tons of lime over the hill so that it soaks into the bogs with the rain. Lime is alkali and thus raises the pH, counteracting the effect of the acid.
A healthy river is one that is fast flowing, with healthy vegetation on the banks, few overhanging trees and a clean gravel bottom. This is all well and good until farming is introduced in the equation. In the upper reaches of the Wye and Usk catchments this is mainly sheep and cattle farming. Stock break down the banks as they enter the streams to drink and in doing so mud is brought into the river and builds up as silt. As the banks break down the river becomes wider and slower meaning less oxygen in the water and the now muddy bottom prevents fish and invertebrates laying their eggs in the gravel bed.
Farmers seldom have time to cut back the trees on the river banks over time this shades out the river and the trees eventually fall into the the water and causes blockages preventing salmon from returning to their spawning grounds.
The solutions are straightforward but expensive and labour intensive.
It does not too long for visible effects to show and within twelve months the trout and salmon ( as well as insects, birds and mammals) will begin to colonise the rejuvenated stretches. This is a very simple and brief piece on the extensive and very scientifically based work of the Wye and Usk Foundation and I encourage you to find out more about their work from their website and sign up for their regular email updates.