Poundbury Hill Fort willow island project

Frome Piddle & West Dorset Fisheries Association
Dorchester Fishing Club

The Frome Piddle & West Dorset Fisheries Association, and many thanks to the West Country Rivers Trust, is funding a habitat improvement project, the construction of two willow islands on the Dorchester Fishing Club water just upstream of Dorchester, by the Poundbury hill fort grid ref SY 6746 9222.

This area has seen several other enhancement projects take place all with great success.

Work was completed in the early autumn of 2010 when the water level was at its lowest, Salmonid movement at a minimum, and any breeding of mammals and birds finished, in fact there is no negative ecological impact on the area.

The above picture shows the two finished islands (September 2010) these will fill up with silt over the winter
The work was carried out by Casterbridge Fisheries Ltd staff and over seen by the FP&WDFA project manager.

To create two small islands to add a variation to the very uniform flow in this area, displacing some of the silt build up also adding natural woody debris encouraging various invertebrates, possibly native Crayfish and creating another suitable area to encourage spawning Salmon and importantly cover for 0+ Salmon and Trout Parr.

The posts for the frame of the two islands were driven in by hand, with 500mm centres and driven well into the bed of the river to a depth of at least 750mm to prevent any movement over the coming years.

All the willow needed to create the structures was harvested on site, woven around the outside stakes creating a solid framework before filling the whole island with willow mattress, and then the structure is wired in tightly to prevent any winter wash out.

The structures over the winter months gather and collect silt, providing nutrients and a firm base for the willow to grow come the following spring.

Other islands previously constructed on the fishery (Thanks to Environment Agency funding) have been outstanding, one island actually resulting in a large gravel shoal forming upstream of it creating some stunning Minnow spawning habitat, and to see well over a thousand of these little fish in their spawning colours gathering in an environment that we delivered was very rewarding.

We are seriously impressed with our design of these islands, they deliver a great enhancement at a sensible price, and we will be exploring many other sites for instillation.

The above picture of the islands, which were constructed in the autumn of 2009, about 500m downstream of the two new islands, clearly showing the change in the river bed and the early spring growth of the island, now full of silt after the winter.

This short reach was clearly over wide and during times of low flow full of dead weed (of various species namely Ranunculus) and the gravel bed covered in Algae, over this summer the bed stayed clean and there seemed to be a steady population of 0+ Salmon and Trout Parr, and an abundance of Minnows, Bullheads and Stoneloach.

This latest island enhancement took place not far up stream of these islands and we are extremely confident of similar results.

john@riverworks.co.uk – www.riverworks.co.uk
Casterbridge Fisheries Limited