Myself and two members from the Environment Agency (Catchment Co-ordinator and Geomorphologist) went on a walk over of Bury Brook at the end of October this year. The aim was to identify/confirm reasons for WFD failures and also to identify what actions could be taken (long term, short term and by EA or others) to try and improve the health of the river. The following are my observations and thoughts:
- Flow: Flow rates were generally slow. The river has been over widened for drainage purposes and relies on surface water run off to feed it. As it is on clay bedrock it is probably a flashy river and we visited after a period of low rainfall which might account for a lower flow rate but some river stretches were extremely slow indeed, leading to…..
- Sediment: in many places the river had a deep layer of silty sediment. This is probably caused by run off from fields and slow flow.We did see sites where the slope of the fields, lack of natural barriers (hedgerows etc) and limited /no buffer strips would be likely to lead to high run off rates. Deep layers of sediment do not make good habitats for invertebrates or fish and act as a source of stored nutrients which adversely affect river water quality and associated wildlife.
3. High phosphate levels: were indicated by large amount of nettle growth upstream and various algal growths downstream including filamentous algae. The most likely cause of these high levels upstream is run off; downstream there are two sewage treatment works which might also be contributing phosphates into the river.
4. Some good signs : where the river has had “light touch ” management it is showing signs of reverting back to a more natural state. In places the bed was gravelly with varying width and flows and it was even beginning to re-meander within its deep channels with the occasional berms or islands developing. On the golf course quite far downstream the EA had done some restoration work and created artificial berms.
So what could we do?
- Investigate phosphate levels upstream in high flow conditions
- Consider what actions could be taken to reduce field run off
- Selective bank clearance where it is heavily overgrown to create more varied habitats
- Further sediment removal to create artificial berms/pools