ISAC - Stream Restoration

Habitat Restoration

In 2007 WUF conducted a trial on a tributary in an adjacent catchment during which the hazel was pleached into the channel rather being removed during the coppicing process. The intention was to increase the amount of lateral woody debris in the channel, accelerate the recovery process, increase channel structure and provide high flow refugia. In 2010 we studied the electro-fishing data for this stream and its two neighbours. We found that prior to the work the site had been performing in line with its neighbours, but since the works it has been showing a 473% increase in salmon fry numbers and a 176% increase in salmon parr.

This modification to the technique has been employed in ISAC and has extended tree work to include some of the less heavily shaded areas. Results of 2011's electro-fishing show a similar or better effect at the sites completed during the winter of 2010/11.

Work started in September 2010 with 6.8km of coppicing of the over shaded lower Chwefru and 8.4km of the moderately to heavily shaded sections of the South Dulas. In addition 3.1km of the Garth Dulas, including a section heavily degraded by uncontrolled livestock access, was also targeted, although tree work at this site was limited to the pleaching-in of woody debris.

Update March 2012:

The 2011/12 winter coppicing season has finished with a total of 27.1km of riparian strip completed, bringing the project total to date to 45.6km of single bank. Once 2012's summer work has been completed this will bring the project total for habitat of SAC designated streams brought into favourable condition to 23.5km.

Fencing works started in April 2011. The first year's fencing and provision of alternative water completed in late October 2011. 7.7km of single bank fencing has been erected on the South Dulas, 4.1km on the Chwefru and 1.8km on the Garth Dulas so far. This combines with existing good fencing already in place to restore 11.4km of SAC designated tributary.

The initial survey determined the following requirements for instream works:

3 sites on the South Dulas, 2 on the Chwefru and 1 on the Garth Dulas were completed in 2011.

In 2012 we are extending the riparian survey to include upper middle reaches of the main stem of the Irfon now that the acid waters are being ameliorated. Aerial surveys show this area to need extensive works.

Update 31st March 2012:

Progress is shown in the table below. 2 more years fencing 2011/12 and 2012/13 and one more years tree work will complete the projects aims.