November began with a meeting between staff from the Stour Internal Drainage Board and their contractors Rhino Plant to review the cutting of Shalmsford Street Dyke.
The dyke once supported white clawed crayfish and was a nursery ground for trout but has become degraded with silt covering gravels and an excess growth of watercress across the channel.
These problems are exacerbated by high nitrate levels and poaching of channel banks by livestock. Sheep stand in the channel to graze the watercress causing further poaching and nutrient enrichment.
Fencing would be one solution but landowners often don’t want the expense. Fencing can also cause problems for rivers if the fence line is too close to the channel edge and prevents bankside management. When this happens river banks can begin to scrub up creating dark channels which are impossible to manage.
During the meeting we looked at ways the cutting of the channel could help alleviate the situation. Narrow channels are often faster flowing with better oxygen levels and less silt drop out but this needs to be balanced against flood risk.
We decided that parts of Shalmsford Street will be cut manually which creates less disturbance to the channel bed and can give a more sinuous cut working with the natural processes of the river while other parts will be machine cut in order to create more open conditions to allow for winter water levels.
A further meeting took place with the IDB and EA in the middle of the month to talk about improvements to Buxford Dyke, near Ashford. Again poaching by livestock is causing issues here, pushing banks and silt into the river where it can cover gravels. Other sections of this channel are prone to drying out and there is potential to create off line ponds which could provide refuge for macro invertebrates during drought periods. Further discussions are needed with landowners before work can take place.
November also saw the annual IDB AGM where I gave a presentation to the board on the work we have completed in the last year and some of the challenges we face including managing invasive species on Chislet marshes and deciding which IDB channels to reduce maintenance on as we take on management of main river channels as part of the Environment Agency Rationalisation programme.
The Rationalisation Project looks at changing the status of some of our main rivers downgrading some of the smaller channels to Ordinary Watercourses. This would allow the Environment Agency to reduce the cost of its maintenance programme.
It is proposed that the downgraded rivers are managed by the Internal Drainage Boards, whose costs are met by landowners who pay drainage rates for the channels to be managed. Several areas have been chosen to trial the project and the River Stour board is potentially one of the pilot areas, chosen partially because of its good environmental track record.
As the River Stour Board takes on the maintenance of more kilometres of river then they need to reduce maintenance on channels they currently manage. One of my main areas of work at the moment is deciding which channels would most benefit from reduced maintenance.
This project offers great potential to improve habitat for species such as Shining Ramshorn snails who like rivers with more in-channel weed and I have been liaising with Kent Wildlife Trust to choose which ditches in areas like the Ash Levels would benefit the most. Other species prefer more open water habitat and here I have been talking to the County Plant Recorder to make sure that channels with species such as hair like pondweed continue to be managed on an annual basis.
This will create one of the biggest changes in the drainage district for many years but one which provides exciting opportunities for wildlife.