Q & A

Question

River Yeo – Waverley House next to Curzon Cinema

I know you guys are keeping a weather eye on the River Yeo, but I have noticed over the past few days that the levels are very low and that there is a large amount of weed growth, and I know that you cleaned up a few weeks ago. Have you any idea what is happening ?

Regards

Estates and Facilities Manager NHS North Somerset

Answer

The Environment Agency are understandably concerned about the risk of flooding as a result of recent heavy rain and the forecast of more to come.

I may have mentioned that the Land Yeo flood flows can be released into the Blind Yeo on the Tickenham side of the Motorway, recently the level in the Land Yeo has been dropped by as much as 12″, at the moment it is down by about 8″.

By doing this the river capacity can be increased if a torrential downpour were to occur in this area, also the drainage of the farmland to the east of the motorway is improved.

With the rainfall we have had, attaining a lower level is the opposite of what you would expect. As a group we have put a lot of effort into improving the flow of water in the Land Yeo and when the levels are lowered the flow virtually stops, however we appreciate that sometimes the Environment Agency  must take these steps to reduce the risk of flooding.

On the question of the rapidly growing weed, it is a species of  Watercress. It spreads like wildfire, as clumps break off the main body and float downstream, forming viable plantlets further along the river. It is a species that only grows in pure water, so in a way we are ‘victims of our own success’. However, the Environment Agency tell us that they have a successful way of dealing with it, so lets hope it will soon be less of a problem. We have removed several weed problems only to be faced with another, ‘the lively swings and roundabouts of life’.
Question

Whilst I appreciate the work you have done, myself and my neighbours are deeply concerned over the ever decreasing level of the the Land Yeo. We live in Yeo Way and our houses back onto the river. Over the past 2-3 years the river level has dropped increasingly year on year. I have photos of the different river levels and whilst I understand it drops slightly in the winter, the evidence is apparent on the river bank which clearly shows previous levels. The banks are now frequently collapsing and the bottom is clearly visible. The levels are at least 18″ lower than they were 3 years ago. Whilst I have had a conversation with Stewart Edwards regarding this I do not feel that your organisation are too concerned about the levels. Your brochure picture distributed to all households, shows the river level as it used to be,  a far cry from today’s level . You say you wish to maintain river levels, what are you doing to promote a higher level or are you just accepting the levels set at the outlet and tilting weir at Cooks Clyse. The river has been dropped and we are not happy about it, if it carries on the way it is going we will be left with nothing more than a stream.

Thanks,  Nick Lester –  Yeo Way Clevedon.

Answer

Nick, there has been a recent temporary lowering of the water level at the Land Yeo Outfall.  This response and update will hopefully answer the points you have raised and address your concerns.  I know you are already aware of some of the following, but thought it worth including, for the benefit of others, who will also read it on the Website.

The LYF have always appreciated the importance of flow in improving the health of the river. Flow has improved  water quality, thereby avoiding the algae blooms and fish deaths that have occurred in the past,  we feel it is a very  important factor in improving the health of the river and the whole of the wildlife habitat.

Other factors affect the flow, apart from adjustments to the river levels that can be made on the other side of the motorway at Cooks Clyse and at the tilting weir incorporated into the Outfall in Marshalls Field.   If a blockage or restriction exists anywhere in the town section the flow of mostly good quality spring water from upstream, is diverted down the Yearling Ditch into the Blind Yeo, thereby completely bypassing the town.  I can assure you from my own observations for a considerable period of time, this has been 100% of the flow from Tickenham, so in effect the river through the town has been nothing more than a long pond, (stagnant in places) from the motorway to the Outfall.

Having identified three major blockages in the town section (two in culverts underground) and by sending hundreds of emails, also phone calls and letters, by our gentle powers of persuasion, we have convinced those responsible that these obstructions should be removed.  I am very pleased to be able to tell you that the third and final blockage was removed from the culvert under Shopland’s Saw Mill a few weeks ago.

Now the blockages have been removed, in order to achieve a flow, the level in the river at the outfall needs to be lower than the level on the other side of the Motorway.  In answer to your question we have explored the possibility of a higher level at Cooks Clyse and a meeting was held with the Environment Agency and the North Somerset Internal Drainage Board.  The NSIDB has similar powers with regard to rivers as the EA, their responsibility with regard to the low lying land between Clevedon and Nailsea amongst other things is to maintain drainage.  The setting of the tilting weir is controlled by the EA. The EA and the NSIDB between them determine the levels for summer and winter, (winter Dec 1^st to Apr 1^st). The level has to be lower in the winter to help prevent waterlogging of the farm land. Basically it is not possible to increase the level at Cook’s Clyse, without a detrimental effect on drainage.

So there you have it. If the river level is returned to where it was three years ago by holding back water at the Outfall, the level will be similar to that at Cooks Clyse and in the winter the flow will stop.  The good news is the water level and flow will soon increase by the setting of the summer level at CC, this could be before April 1st if the relatively dry weather continues.  As this will be the first occasion the town section has been clear of blockages for many years, we are hopeful of a significant improvement in flow, resulting in a level increase of 4” to 6” at your end.  The level was recently lowered by about 4” (compared to last winter) to increase the flow on completion of the culvert cleaning.

Unfortunately slumping of the river bank  is a common problem, although fluctuating  levels don’t help, I believe that the type of soil,  the banks being  very steep, and frost damage, are the main causes of the problem.  I spent £600 on materials (approved by the EA) a few years ago to reinforce the bank in my garden, if you need any information I would be pleased to help.

Considering the above, we hope that you now accept that as an organisation our concerns do include levels and that we have explored the possibility of an increase upstream.  In addition we hope you accept as we have, any return to the levels you remember at your end will have an effect on flow, and a detrimental effect on the rest of the town section of the river.  Going back to winter periods in the 90’s I can remember when the river level by Marshall’s Field was so low that bricks and stones were showing above the surface, I am not suggesting that we should go back to that, I do however feel a winter water level of 4.3 metres, set at the outfall is a reasonable compromise, when taking the whole of the river into consideration.

If you or your neighbours still have any questions or concerns, my previous offer still stands, we can arrange a walk out to Cooks Clyse to see how it operates and see where the river level is relative to the land, if you would like to do this walk, please get back to one of us.

Stewart Edwards       March 2012

Question

Why has the end of the Land Yeo from say Strode Road to the sluice become so cloudy over the last two or three years. I used to fish the last section and it was more or less clear. Now you can’t see any more than a few inches below the surface.?

(question received by e-mail 22.6.2011)

Answer

It is believed that this happening because three years ago the river through the town was more like a long pond due to the lack of flow, most of the water from upstream being diverted into the Blind Yeo on the other side of the Motorway.

The Queens Square Culvert blockage was cleared in Dec 2009 and the Willow tree growing in the river at the back of Coleridge Road was removed earlier this year. Both of these were severely restricting the flow, allowing silt to build up on the river bed. Also as a result of poor flow, the water and silt became stagnant. The situation has now changed and the water at this end (by the Medical Centre) is now crystal clear, and flowing. As a result there are more creatures living in the silt.

The feeding habits of the Ducks has changed in the last couple of years, they can now be seen diving to reach the silt and the creatures that live in it, where the river is shallow.

Likewise the Swans and Cygnets are feeding on the weed growing on the river bed, this feeding activity is disturbing the silt putting it back into suspension in the water.

Because there is more flow which may not be so obvious where the river is wider and deeper, the silt in suspension is migrating towards the Pill, which is as it should be.

It is expected the situation will improve in time as the build ups caused by the blockages gradually get washed away.

The Environment Agency should soon be de-silting the river to the East of the town, down as far as Northern Way, this should reduce the possibility of more material being carried into the town section.

22/6/2011

Question

Willow trees that has its overhanging leaves touching the river. The question was:-

Will these start to take root if they make contact with the riverbed?

Answer

If the leaves are simply touching the water then there should be no risk of anything taking root in the river bed. The soft tips of the shoots and leaves can’t grow under water and will either rot back or be nibbled off by ducks etc.

All willows can potentially self root from pieces of branch stuck in the mud so it’s certainly worth checking regularly for, and removing, fallen branches.