COUNCIL chiefs are assuring anglers, residents and visitors that everything possible is being done to control weeds on the canal in Warrington’s Sankey Valley Park.
But it could be several years before any improvement is noticeable, they have warned.
Problems are being caused by a range of aquatic plants. Some species remain submerged (hornwort), some are rooted in the canal bed but with leaves that emerge through the surface (water lily) and other plants float on the surface (azolla and duckweed). These plants can cause oxygen levels to drop during the night, which can impact on fish.
The council has developed a water management plan to address the issues, in partnership with the Environment Agency and the Dallam and District Community Angling Club. However, the council has stressed that it may take a number of years before people begin to see a real impact.
The council’s cabinet member for leisure and community, Cllr Tony Higgins, said: “Green weeds and plants in Sankey Valley canal present a number of complex challenges for us. These are not easily overcome, as when we successfully remove one type of weed, it provides opportunities for others to flourish. They take advantage of this and reproduce rapidly.
“We know that these are unsightly and can impact on fish stocks, and we are listening to the concerns of local people. We are taking a pro-active approach, working with the Environment Agency and the angling club. Together, we are doing all we can to manage water plants on and in the canal to improve the look and appeal, benefit wildlife and improve angling. But it will take time.
“While this will not be resolved overnight, I want to ensure everyone that we are working hard to improve the water for anglers, walkers and everyone else who enjoys this important asset.”
A major challenge at the canal currently is the rapid growth of a number of species of water lily. This plant, although beneficial to wildlife in small quantities, has developed significantly in recent years. Physical removal is very difficult as the plant regenerates with increased vigour from any small root pieces not removed.
The council will be spot treating a number of the plants this year with a herbicide, under licence from the Environment Agency, to reduce the coverage, with the aim of creating a central channel of lily-free water between Sankey Way and Callands Pool.
The lilies will be treated towards the end of the growing season, when plant nutrients are being reabsorbed by the plant as it naturally dies back for the winter. This is the most effective time to apply the herbicide, as it is absorbed into the root.
The treatment programme will be sustained over a number of years and its success monitored.
Steps are also being taking to deal with the challenge of surface weed on the canal. Weed coverage experienced earlier in the year was predominantly Azolla, a non-native, fast growing plant. As in previous years, the council is managing this through biological control, introducing a specific species of weevil that only eats the Azolla plant.
This approach has proved to be a success, with azolla now scarce along the canal.
