Decision details

To grant a Licence to Access and Occupy relating to land off the Amersham Bypass to Quarrendon Mill, London Road East, Amersham to Affinity Water for the period of 28th September 2020 to 30th December 2021

The Licence will give Affinity Water the right of access and occupation in order to carry out river restoration works which includes channel re-alignment and re-grading, installation of fencing and cattle crossing points along the new channel, in-channel works (installation of raised benches (berms)), creation of an informal wetland area and 300mm raised earth bund, and like for like replacement of a small footbridge.
This project will considerably improve the functionality of this stretch of the River Misbourne which in turn forms part of a future long term plan for the whole of the River Misbourne by Affinity Water.
The River Misbourne, Water Framework Directive (WFD) waterbody is failing WFD criteria for its Hydrological Regime and Fish. The river has been negatively affected in the past by channel straightening, the building of weirs and other barriers, over-widening and re-location away from the valley bottom, often into millstreams.
Affinity Water was asked by the Environment Agency to address morphological (physical habitat) issues in the depleted area (i.e. the area affected by extraction; Great Missenden to the M25 at Denham) as well as to reduce the extraction of water in the catchment.
The 1km long project area which affects the Councils land lies to the south of Amersham (see append/attch). The river passes through a rural landscape, initially through pasture, then between arable fields and finally bypasses around the north of Quarrendon Mill.
This whole section of river is artificial; with the original natural channel some 60 – 70 metres
to the south-west. The channel was diverted in order to provide water to Quarrendon Mill.
The mill is no longer operational.
The artificial channel is unnaturally straight and, being away from the valley bottom, is
disconnected from ground water re-charge. In turn, this means that the river is more prone
to drying than it otherwise would be. Conversely, during times of high flows or channel
blockages, water spills out and runs across the fields to the bottom of the valley, re-joining
the river via the remnant channel to the south of Quarrendon Mill.
The recommendation from Affinity Water was that this section of the River Misbourne is
returned to the bottom of the valley as close to its original course. By returning the river to
the valley bottom, the river will be better connected with ground water re-charge and will
therefore be more resilient to low-flows. Moving the river to its original course will reduce
the risk of flooding whether caused by high flows /blockages in the channel.
Officers have been working with Affinity Water on the proposals over the past couple of
years and a report was submitted to Chiltern District Councils Corporate Asset Management
Group (CAMG) on 25th July 2018.
Members agreed to support the proposal to relocate the river to its original course and to
authorise the Head of Environment to take the necessary action to proceed and implement
the proposal in consultation with the relevant Portfolio Holder.
Consultations with stakeholders have been undertaken including the Council’s Tenants, the
Town Council, Legacy Council Ward Members, Chilterns AONB Chalk Stream Officer and the
River Misbourne Association.
There is no financial contribution required from the Council for this project as it is being fully
funded by Affinity Water through the National Environmental programme in connection
with the Water Framework Directive (WFD).
The Agricultural tenants have been kept fully informed throughout the process and are
supportive of the project. The two tenants have signed the Licence in the last week.
Affinity Water have appointed a contractor to carry out the works and the contract is due to
start on 28th September 2020.

Not Applicable