In August 2021, 460 tons of gravel were added into the Black Water of Dee as part of the restoration project. This followed a habitat survey by GFT in 2016 which identified that a lack of small spawning substrates were a key contributor to the lack of fish in this river. This led to the development of The Black Water of Dee Restoration Project which involves several organisations such as DRAX, GFT, SEPA, Dee DSFB, Galloway Glens and FLS with partial funding from Galloway Glens.
The project is ongoing with opportunities to volunteer with future works to further restore this river.
The Black Water of Dee is the largest tributary of the Kirkcudbrightshire Dee. Nearly 20km of the lower Pullaugh Burn and Black Water of Dee is accessible to migratory fishup to Clatteringshaws Dam but very few fish were found here partly due to the setting of a low compensation water flow from the Dam. This was improved in 2012 when Scottish Power increased the compensation flows from the dam and re-establishd flow down the lower Pullaugh Burn which had been dry for 80 years. An improvement in trout densities was recorded following the increase in flows however there was still an absence of salmon at each site.
In 2016, an extensive habitat survey was undertaken by GFT which highlighted a lack of small substrates within the river which would provide spawning grounds for salmonids. It also identified areas where conifer trees (both planted and naturally seeded) were in close proximity to the watercourse which causes various problems. There were few deciduous present on the river banks. Deciduous trees are beneficial to fish for several reasons – they bind the soils which prevents erosion while providing shade and cover for the fish. Following this survey, the Black Water of Dee Restoration Project was proposed and extensive planning of the works began in 2020.
In August 2021, a total of 460 tonnes of gravel were deposited into four sites along the Black Water of Dee with one site on the Pullaugh Burn. Sites were selected based on the physical characteristics as it was required for sites to have adequate flows to carry gravel, enough width to support the addition of substrate, and accessibility for the contractor vehicles. Two of the sites required access ramps to be built for the diggers to get close enough to transfer gravel into the water. Gravel was deposited in instream piles in the main channel at each site and also used to create sloping banks to imitate natural gravel banks. These methods allow river flows to gradually carry gravel downstream to settle naturally.
The gravel is being closely observed to monitor downstream transportation. There are time-lapse and motion capture cameras in operation at selected sites along the Black Water of Dee to monitor progress. The gravel is also checked visually to monitor any changes. Winter floods will push the gravels downstream allowing it to create spawning grounds for salmonids. Geomorphological surveys looking at substrate compositions were undertaken at selected sites before the gravel was deposited and are being repeated to further monitor gravel movements.
Ongoing plans for the project include continuing to monitor and add gravel to each site regularly to achieve and maintain an adequate volume of spawning substrates within the river. Mapping natural conifer regeneration in the riparian zones and removing it where it causes impacts will benefit the river as a whole. Areas which would benefit from riparian deciduous trees are to be identified followed by the planting of native trees. Planting the deciduous trees will require the help of volunteers and any involvement from the public will be greatly appreciated.
As December is right around the corner, I am sad to say that my internship here at GFT is nearly over. However, I am grateful for my experiences at the trust and there is still plenty for me to get up to before it does come to a close.