ALMOST exactly five years on from its first test, Slowing the Flow (STF) in Pickering has once more proved its efficacy and value for money.

A couple of months with frequent pulses of heavy rain have left catchments across the whole North York Moors fully saturated, causing rainfall to run off rapidly into watercourses with virtually no infiltration. Against this backdrop, two days of persistent steady rain from Storm Cristoph on 19-20 January caused all the rivers to rise quickly to near record levels. The Natural Flood Management (NFM) and beaver dams in the upper catchment quietly did their job of slowing the flow by temporarily storing water and evening out the flows.

Meanwhile, the Pickering Flood Storage Area (FSA) started to impound water behind the bund for the 35th time since its completion in September 2015, with the level peaking at 3.49m, breaking the previous record level from Storm Desmond on Boxing Day 2015 by just 2cm. The flood water levels in Pickering town’s Beck Isle area were held relatively constant, while around 6,000 m3 of water that would otherwise have flooded parts of the town sat safely in a remote field up Newtondale. No properties were reportedly flooded. The bund has currently impounded the flow of Pickering Beck on 38 occasions since completion, 11 of these in the last two months.

Since my first involvement with flooding issues in 2006, when STF and NFM were considered to be weird and whacky unproven theories, it’s heartening to now hear this exact terminology on a regular basis in the media from people at the highest level, along with ‘effective upland, river and land management’ and suchlike. How opinions change with the right persuasion. It’s a relief to stop banging my head against that particular brick wall. It was also heartening as a member of Ryedale District Council’s (RDC) planning committee to attend a site visit to the proposed River Foss FSA – a similar but much larger bund to Pickering’s – and then to grant approval for the application in December. It will provide up to 1million m3 of flood water storage NE of York to protect almost 500 properties against up to 1:100 year events. The concept is clearly no longer unproven. It also slows the flow for the whole length of the river system downstream, rather than just protecting properties in the immediate vicinity. An important feature of NFM and FSA schemes is that their effects are cumulative, so new measures could be added to increase potential storage should the need arise and the funding made available.

It must be borne in mind that in the case of extreme flood events when the storage capacity is exceeded, these bunds will overtop and flood areas downstream, in a similar way to flood walls overtopping. C’est la vie. However, at least there will be warning of a fairly exact time for this to happen.

These bunds, which fall within the strict auspices of the Reservoirs Act, are deliberately designed and built with a reinforced spillway in line with the main channel to protect the structure from fast flowing water whenever it overtops. However, farm vehicles using the crest of the Pickering bund as a through route have created deep ruts in the lateral bund that protects the railway line. If/when the bund fills to capacity, this could result in the lowered and weakened section becoming an unprotected spillway, with potentially serious results. The Environment Agency (EA) were aware of this a year or two ago, but I sent a gentle reminder, ironically just four days before the record level was reached.

The beavers in Cropton Forest continue to thrive. The original two released by Forestry England in a secure compound in April 2019 are now a happy family of six. They have built an incredible dam right across the valley, up to circa 6ft tall, turning the boggy remains of two former ponds into a significant water storage area, with multiple benefits. The positive effects on biodiversity, floodpeak reduction, flow attenuation etc are being monitored and compared to the baseline. The timber mini-bunds built in 2009 are showing their age. Assuming the cost of replacement will not be forthcoming, hopefully the beaver family will oblige in due course with effective alternatives.

* One of Mike's recent Zoom talks about NFM and beavers is available at

He also posts relevant news and links on the STF Pickering Facebook page.