The Mile Field is an agricultural area of a flood plain on the Western Cleddau immediately downstream of St. Catherine’s Bridge, at Camrose. This is a part of the river where the Pembrokeshire Rivers Trust and the Environment Agency have carried out major habitat improvement works.
The site was for many years used for the grazing of livestock with, no restrictions in place on access to the river. This resulted in wide spread damage to the banks and bed of the river (by both grazing and trampling), causing erosion and fouling of the water due to sediment stir up and biological waste. This disruption of the natural progression on the physical river and the flora which contribute to the structure and integrity of the river banks and bed has had significant effects on the fish stock levels in the river and many other types of fauna.
The project
The project at the mile field is the first site on the Western Cleddau trail that Pembrokeshire Rivers Trust and its partners took from the drawing board stage right through into practice. Much of the development at the site has been carried out, and with physical maintenance the environment should start to return toits natural state. The site has backing and support from many quarters. Countryside Council for Wales have committed to the provision of compensation payments to land owners and farmers whose land is affected, as well as for the maintenance of the fencing at the site for ten years. PRT and Pembrokeshire Anglers Association are committed to supervision of the maintenance and to continued monitoring and support of the site.
Features of Interest
This is a demonstration site on how to counter the effects of land drainage and intensive farming. Considerable work has already been carried out by a fencing contractor with guidance from the relevant experts working for and with PRT. A range of protective measures have been put in place such as a fence running down both sides of the river to keep livestock from grazing the banks and entering the river at will, disrupting the sediment and eating the flora. Cattle watering bays have been installed for the drinking purposes of the livestock but this is limited to specially managed areas allowing the cattle to use the river without the damaging effects of free access. Boulder banks have been installed on some areas of the riverbank deemed to be eroded badly. Habitat forming is an on going process in the river helped by the laying down of new bedding materials and the clearing of silts; these types of improvements aid habitats important to young or spawning fish.
All of these measures are depicted on panels situated around the site, giving a brief description of the work done to date and the desired outcome.
Riverside Habitats
Tall plants include reeds, tall flowers and brambles, many of which are grazed by cattle and if unrestricted this can occur right to the waters edge, eliminating the current flora and stopping the growth of new plants from developing.
This disappearance or even reduction of flora at a rivers edge can cause many problems; the effects on the fauna of both the terrestrial and the riverine environments are considerable. The shade supplied by riverside flora is crucial in the development of a site for fish to both spawn and survive as juveniles.
Riverside flora also provides a habitat for many insects on which fish and birds rely for nutrition. Mayfly and dragonfly nymphs require grasses on which to crawl up from the river on their emergence as adults. The roots that break through the banks and enter the water provide excellent areas for otters to hide; without these 'safe areas' otters are easily lost to an area and are difficult to regain.
Small rodents such as water voles use reeds as a large part of their diet and fish use the cover where reeds encroach upon the river itself. Branches offer birds a perch, essential for the likes of Kingfishers to hunt. Even the organic debris from the plants is food to freshwater shrimps and many insects. These factors have knock on effects on other fauna that inhabit the riverine environment.
Physically trees and tall plants are just as important to the integrity of the river banks by adding stability through their root systems and their ability to slow down run off from the land, this helps in protecting against accelerated erosion caused by flood water entering the river valley from outside of the river environment but also protects against the on going erosion caused by the natural meandering of a river in the flood plain. A treeless river in the flood plain is much wider and shallower than one with trees and is more prone to the effects of the river when the flow is increased or there is flooding.