Motorised boat traffic on the Shropshire part of the Montgomery Canal has reduced the numbers of water plants and invertebrates that live in the water. This is because the water has become turbid (cloudy with mud) due to disturbance of the mud at the bottom of the canal. The motors on the boats and the speed the boats travel churn the water reducing the light levels and creates wake which breaks the rafts of floating plants up. Dredging to maintain the channel so it's suitable for boats also causes muddy water. Even a small amount of disturbance reduces the amount of floating water-plantain (Willby & Eaton 1993).
We know motorised boating will cause damage. Here is an example from part of the canal in Shropshire. The Aston Locks to Keeper's Bridge part of the canal was designated as a SSSI in 1986. It was restored and reopened in 2003 and by 2013 Natural England reported that the site was in an unfavourable condition due to the public access, associated disturbance and pollution.
Pollution is also a reason that the Shropshire end of the canal has become unfavourable (Newbold 2001). Fuel and waste water can all end up in the waterway. Not only does this impact the plants and invertebrates, but also to birds, such as swans, that breed on the canal.
Government guidance on SACs state that competent authorities such as Natural Resources Wales and any one holding public office (councillors and planning commitees) have a duty to prevent significant disturbance of the site's designated species from human activity.
Please ask Powys County Council and Canal & River Trust to not allow motorised boating on the canal to prevent significant disturbance of this wildlife-rich waterway.