River Misbourne Environmental Restoration Project.

Following our recent visit to The Misbourne Valley where we came across the environmental restoration project, I was curious to learn more, so contacted Tina Abbott at Chiltern & South Bucks District Council, who kindly replied with the following interim update on the project, with a full report to follow on completion of the works in the Autumn.
Many thanks to Tina for taking the time to respond with the article below:

The section of the river where the waste recycling site is located is part of a losing reach. This means that characteristically the river does not flow, it is dry, for certain times of the year. This is because the groundwater levels are usually lower than the river bed levels (the channel is perched above groundwater levels and chalk streams are typically dependent on groundwater levels- that is what ‘feeds’ the flow). Also, for some sections of the River Misbourne, including around London Road depot, the channel does not follow its original course as it has been moved/straightened in the past for a number of reasons (for example, as you know, the channel was straightened between Amersham and Quarrendon Mill for the mill, and originally meandered and flowed through the bottom of the valley).

Prior to the tree works, some parts of the reach between Amersham and Quarrendon Mill were heavily over shaded allowing limited light into the river. Therefore, the aim of the tree works was to create dappled shade in the channel and allow more light into the river. This is to encourage vegetation on the margins and in the channel to establish which should help to create flow diversity (slow and fast flowing areas). In addition, with maintenance, this will improve the health of the trees. This will also be contributed to by the creation of in-channel benches, which form part of the planned river restoration works.

These more natural features will create habitat diversity for plants, fish and macroinvertebrates. Moving and re-meandering part of the channel to the bottom of the valley should help to reinstate natural chalk stream features and improve the rivers connection with groundwater. The channel through this section is currently perched above the valley bottom and groundwater as it was historically diverted and straightened away from its original course to provide water to Quarrendon Mill.

The driver for this work (the river restoration works) is the Water Framework Directive (WFD) as the River Misbourne is currently failing to achieve Good Ecological Status. The aim is to achieve GES by 2027. This project is at no cost to Chiltern District Council and is fully funded by Affinity Water in conjunction with Water Framework Directive.

Tina Abbott

Estates Officer – Joint Estates Team
Chiltern & South Bucks District Council.