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From a Thames lock keeper
Martyn G
Posted December 28, 2015 at 9:32 am | Permalink
I have been a volunteer assistant lock keeper on the river Thames for the past 4 years and modestly suggest that I might know something whereof I speak. The Oxfordshire section of the river Thames was not dredged at all this year. In fact, I put a dredger and its barge through the lock I was working at the start of the season, after which it was berthed at Abingdon lock and didn’t move for the next 6 months. At the end of the season it returned downstream for winter, having not once being put to use. We were informed by the EA that they were in dispute with the Fisheries Agency, who had effectively banned dredging to protect the fish and water life. I have no idea whether or not the EU was behind that.
There is concrete visual evidence that, in the absence of dredging, silt levels have significantly built up over 2015. At the start of 2015, downstream of my local lock weir there were 2 green buoys (keep on your right going upstream, left downstream) marking the edge of the edge of the navigable channel. There are now 5 green buoys marking the greatly expanded silted up shallows and 2 red can buoys (keep on your left going upstream, right downstream) showing by how much the channel has been reduced over 2015 alone. Over the boating season the lock is filled and emptied many hundreds of times and each time the lock empties to let boats downstream, thousands of gallons of water flush the channel and act to keep it relatively clear of silt. But the silt has to go somewhere; hence the addition red dan bouys because silt flushed along the channel has built up against the downstream right hand bank of the river where it bends to the left.
Over the past 2 or so months there has been a small handful of lock movements, hence little water to flush the channel and it is entirely predicatable that the channel will become even narrower without dredging in 2016. The commercial users of the river using large passenger boats are likely to find their businesses affected by narrowed and shallowed navigation channels. There is another predictable matter, in that we haven’t had a great deal of rain recently, but nearby weirs have opened most of their sluices and put out ‘red boards’ warning of increasing stream (speed and strength of flow). Predictably, if we get heavy and persistent rain in this part of the world, the increasing silt buildup and narrowing navigable channels will restrict the ability of the river to pass the increased stream and flooding issues will arise at an earlier stage than would otherwise be the case. Listening on the radio and TV to those in the badly flooded areas this morning, it seems pretty clear that lack of dredging is at least part – perhaps a major part – of the problem for those unfortunates affected by flooding. Note that I do not entirely blame the EA for this, because I can see that its activities are hindered by reduced funding, political decisions and perhaps not least the ‘green blob’.
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