2020 – February Fill-Dyke

“Enough is enough!”, you may cry as yet more precipitation precipitates, but please don’t blame the messenger.

It will be little surprise that groundwater levels have risen well along the valley and in the Chilterns during the last two months. Indeed, a glance at the rainfall record in our Quickview pix shows that both the three months and six months to end January were some 40% above the three and six month averages – no great surprise there. But, worth noting is that the 12 month total was still no more than the average for a year. This appears to be reflected in the other graphs showing levels are good but by no means exceptional, though maybe end February will show a further leap.

Meanwhile, there is water in Mobwell Pond (by the Blackhorse pub) at Great Missenden for the first time in 4 years and the “upper Misbourne” is flowing through Great Missenden. Recovery from Amersham down was quite rapid during December – aided by our work party and the beginning of the latest EA/Affinity water “restoration project”. Flow then “hung up for several weeks around the Thames Water balancing tanks beside the recycling centre. The late John Norris and previous Chiltern Society RWG chair Roger Lerry were firmly of the opinion that this was a seriously leaking reach of the river due to the disturbance caused by the construction of the deep tanks when the Amersham Sewage Works were removed in 1954. Previously the treated effluent was returned to the river but subsequently the raw sewage has been piped down the valley to Maple Cross – one of the reasons why Misbourne flow is not as remembered by some of our senior citizens.

Anyway, it is to be hoped that a future project will sort this area out with some environmentally sensitive, ecologically friendly, cost effective lining as the porous chalk is almost at the surface where the river turns the corner below the tip back into its original bed through the fields below The Ivy House. That would greatly help the river on its way to the Chalfonts as it is almost always “perched” from Amersham downstream.

Meanwhile, we will do what we can to encourage flow through this area by clearing as much of the last three year’s debris as we can at our next work parties which will be on Saturday 7th March from 09.30am to about 12.30pm and on Wednesday 11th March from 10.00am. Please let me know if you can join us and I will send out “orders of the day” near the time – note that I need to know your shoe size so we have the right waders available.

P.S. Posted 3rd March 2020
Further to my note a couple of weeks ago, the river has continued rapidly recovering from the dry spell since it last flowed through the lower part of the valley in mid 2017.

In fact, I understand from various reports that there is now continuous flow form Mobwell Pond, N of Great Missenden, all the way to Chalfont St Giles village. Excitingly, the “lower river” is also making its way back up the valley with flow through Gerrards Cross Golf Club and lots of springs and some flow N of Chalfont St Peter. So, it seems that it won’t be long before we have continuous flow from top to bottom again.

Without doubt, there has been a lot of rain! However, the rate at which flow has reappeared along the valley is unprecedented in our records and may, perhaps, as suggested before, have something to do with our efforts to maintain the channel. Which brings me back to our work parties this Saturday and next Wednesday where we could still accommodate a few more volunteers. The extent of the newly wetted stretches means that we have literally miles of watercourse awaiting removal of the accumulated debris that has formed lots of mini-dams obstructing the nascent flow.

So, if you can join us, and haven’t already done so, please let me know and don’t forget to include your shoe size (so I can arrange waders). As usual, I’ll aim to send out details of suggested work locations just before the day but they will certainly include central St Giles, parts of St Peter and downstream of Mill Lane St Giles as a minimum.

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