ATC: Works along the River at Barn Meadow

In Nov 2019 Amersham Town Council issued a notice to inform residents of the Old Town of intended works along the River Misbourne at Barn Meadow. The restoration scheme was proposed by Affinity Water which will be funding the project and working in partnership with Environmental Agency and the Town Council. The timing of the works is preliminarily set to start from early 2020 with the expected improvements to the river in 2021.

The notice was delivered to the houses backing on to Barn Meadow. To make it public for all concerned we are transcribing it below:

River Misbourne at Barn Meadow
River Misbourne at Barn Meadow. Shows willow trees and vertical brick wall referred to in the notice

Dear Resident,

15 November 2019

It is with great pleasure to announce that Affinity Water has proposed a river restoration scheme to address morphological issues within the stretch of the River Misbourne along Barn Meadow.

Throughout this stretch, the river is generally overwide and straight with limited flow diversity and marginal and in-channel vegetation. The channel has likely been straightened from its original course and shading from the willow trees has limited the in-channel and marginal vegetation that can establish.

As such Affinity Water, in conjunction with the Town Council, intend to undertake the following works to improve the habitat and the morphology of this valuable chalk stream:

  • Pollarding or coppicing of the willow trees that line the river at Barn Meadow; see photo [above]. Such tree works would allow more light into the river and encourage the growth of vegetation on the banks and in the channel, in addition to improving the health of the trees. A tree survey is to be conducted prior to the works, noting the current condition of the trees and the recommendations.
  • Pre planted coir rolls will be installed to create a more sinuous channel along the right bank next to the vertical brick wall (photo [above]). Once the coir rolls vegetate, the amount of marginal vegetation will increase, and in conjunction with the tree works, should contribute to additional vegetation establishing on the margins and in the channel.
  • Wet ledges could be created on the left bank to increase the capacity of the channel, potentially reducing the risk of flooding. These ledges will also enhance in-channel habitat and increase flow diversity (slow and fast flowing areas). Deeper and shallower sections of water, known as pools and riffles, may also be formed, creating an improved habitat for plants, fish and macro invertebrates.

As noted above, the intended works aim to improve the morphological issues, in addition to reducing the risk of flooding. As such the private footbridges through Barn Meadow will need to be considered in the design and may have to be raised. Needless to say, no works to any bridges would be carried out without permission from the owners.

Affinity Water will be funding all the works and will be working in partnership with the Environment Agency and the Town Council. Affinity Water has undertaken similar projects at Upper Gadebridge Park on the River Gade and at Tewin Water House on the River Mimram, among others, with huge success.

The River Misbourne is arguably one of the Chilterns most important natural features. The river is ideal for a variety of creatures to breed and thrive, however in its current state, the River Misbourne, particularly through Amersham, lacks the natural features and processes characteristic of a chalk stream. It is very much hoped that these improvements will aim to address this issue.

The Town Council has received numerous calls from residents who are concerned that the river is currently overgrown with vegetation. Vegetation has encroached into the channel during periods of low flow and drying through this section of the river as a result of lower than average rainfall. It is expected that the vegetation will naturally die back as flows recover in the winter months. Therefore, Affinity Water has asked that this vegetation is not cleared. The intended works aim to improve the morphology and the habitat for plants, fish and macroinvertebrates which should contribute to addressing this issue.

The timing of the intended works is yet to be confirmed. We are looking to complete the tree works in early 2020 and the improvements to the river to the latter end of 2020/2021.

If you have any queries in relation to these works, then please do not hesitate to contact Grace Harland at Affinity Water at […].

With best wishes,
Amersham Town Council