Oxon Ray Catchment Summary of significant issues affecting the water environment

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Oxon Ray Catchment Summary of significant issues affecting the water environment Introduction This information pack has been produced to support the Challenges and Choices consultation document for

1 Oxon Ray Catchment Summary of significant issues affecting the water environment Introduction This information pack has been produced to support the Challenges and Choices consultation document for the Thames River Basin District. It summarises the key issues in the Oxon Ray catchment and a snapshot of the latest findings from the Environment Agency s rolling programme of investigations. Examples of options that BBOWT, the EA and other local partners have identified are also included. The Oxon Ray catchment has been split into 12 river water bodies and also includes the. Each waterbody was assessed and classed based on water quality and biology. All of the water bodies were found to be failing and therefore required investigations and actions to address the problems. The maps on the following pages display where, current evidence, shows that there are significant negative impacts on the water environment caused by each issue. Each water body that has a major issue has been shaded in blue. More detailed information for each water body can be produced upon request. Significant Issues in the catchment Diffuse pollution from rural and urban areas and transport These sources of diffuse pollution include the impacts from agricultural practice, the M40, local roads and rural land management. In the Oxon Ray catchment the main pollutants arising from these sources are phosphorus and sediment with additional impacts on oxygen levels in the rivers. All are having a negative impact on the local fish and plant life. Livestock and surface water run off from fields are having an significant impact on seven water bodies in this catchment. Some of the potential options that local groups and the EA have identified so far include implementing best practice for farming through schemes such as Catchment Sensitive Farming; installing cattle drinkers or fencing along riverbanks to block livestock access to the rivers and installation of sustainable drainage systems to reduce pollution from urban areas and roads (e.g. mini wetlands and ponds). Due to the nature of diffuse pollution these options have been identified based on the needs of the catchment rather than just within specific water bodies. As such the scale to which they need to be implemented and total costs to reach Good Ecological status is still unknown. Changes to Flow and levels Some waterbodies may not reach Good Ecological Status due to the natural conditions of the rivers. The Oxon Ray catchment is relatively flat and the main source of water is from rain. As such parts of the catchment are susceptible to low river flows, which can lead to poor conditions for river life to grow and thrive. Habitat restoration could be undertaken in the six affected water bodies to allow the river system to be more resilient to low flows and so provide an improved environment. The water bodies affected by low flows are also impacted by physical changes to the river systems due to land management and diffuse pollution inputs. As such there is the potential for tackling all three issues with combined actions such as creating wetland habitats which produce a more natural habitat and can also cope with changes in river levels and reduce the amount of diffuse pollution affecting life in the river. Physical changes to rivers due to land management This is where the physical nature of the rivers has been altered to improve drainage for the surrounding land. This has often resulted in highly channelized stretches which are over-deepened, straightened, widened or in some cases reinforced with concrete. Habitat restoration projects, such as creating meanders, installing gravel beds for riffles and reconnecting the river to the floodplain (e.g. at Otmoor) can remove some of these modifications and revert the river back to a more natural, healthy and functional state. These potential options are all being considered for the six water bodies impacted by this issue. Although these actions have to be properly planned so that they will not increase flood risk to local communities. Invasive Non-Native Species (INNS) Invasive Non-Native Species, plants and animals from outside the UK introduced to UK waters, pose a threat to both native species and the water environment as a whole. In the Oxon Ray catchment, North American Signal Crayfish are suspected to contributing to the problems affecting fish and insect communities in four water bodies. Unfortunately, there is no clear option for tackling this specific invasive species although some techniques for restoring habitat to a natural state have been shown to help. Impoundments such as weir Artificial impoundments along a stretch of a river can detrimentally impact on a river in two ways. Firstly, if an impoundment holds back water or alter the flow regime then this can lead to low flows and associated environmental damage. Secondly, impoundments present an artificial modification to the form of a river. This can lead to altered sediment deposition, damage to natural habitats and the obstruction of migratory routes for fish. Although there are 15 known impoundments with the Oxon Ray catchment only five have been shown to be having a significant impact (e.g. Islip, Irongate, Oddington and Charlton weirs). All in the lower reaches of the River Ray itself. Some potential options for dealing with these obstructions are removing the weirs or installing fish passes to allow passage up and downstream of the obstructions. Water Company and Industrial treated waste water discharges There are 11 major water company sewage treatment works in this catchment, all associated with local towns and villages. Their primary impact is creating elevated concentrations of phosphorus, leading to excessive plant and algal growth in the rivers. These discharges are also contributing to low levels of oxygen and high levels of ammonia in the rivers. Both of which are having a negative effect on the fish and insects. Some potential options that could be put in place are improving the quality of the discharge at all 11 works, although this would be an expensive undertaking. Alternatively small wetlands or other different treatment techniques at small village works could be installed to reduce phosphorus concentrations. This option could also provide habitat improvements, helping to get more environmental improvements for less money.

2 Oxon Ray water bodies WBID GB GB GB GB GB GB GB GB GB GB GB Name Gallos Brook (Bletchingdon Stream to Ray) Ludgershall Brook and Muswellhill Brook Tetchwick Brook, Source to Ray and tribs Bletchingdon Stream Oxon Ray (upstream A41 to Cherwell) including Otmoor Ray and tributaries NorthEast of Grendon Underwood Gubbinshole and Broadmoor ditch to Ray (Oxon) Summerstown Ditch and Launton and Cutters Brook Gallos Brook (Source to Bletchingdon Stream) Langford Brook (Bicester to Ray inc Gagle Brook) Town Brook at Bicester GB Langford Brook (source to downstream A41) GB

3 Rural Diffuse pollution Urbanisation and run off from roads

4 Natural conditions Invasive non-native species

5 Drainage due to land management Impoundments such as weirs!! River obstructions

6 Water Company treated waste water discharges Industrial treated waste water discharges Major Sewage Treatment Works Industrial Sewage Treatment Works

What is happening now and who to contact What is happening in the catchment now A local partnership led by the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust is currently working on

The group s aim is, through partnerships, to create a more natural landscape with unpolluted waters, which is resilient to future pressures and is an attractive place for people to work, live and

Langford Brook upstream of Bicester, Summerstown Ditch, Gubbinshole Ditch and Tetchwick Brook have currently been prioritised for actions based on current evidence and the potential actions that

To get involved with work in the catchment please contact: Catchment host LouisePrint-Lyons@BBOWT.Org.

7 What is happening now and who to contact What is happening in the catchment now A local partnership led by the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust is currently working on improving the rivers in the Ray sub-catchment. The group s aim is, through partnerships, to create a more natural landscape with unpolluted waters, which is resilient to future pressures and is an attractive place for people to work, live and visit. In addition to this the EA and partners are working with Cherwell District council on developments around Bicester, working to improve the local environment for local communities. Langford Brook upstream of Bicester, Summerstown Ditch, Gubbinshole Ditch and Tetchwick Brook have currently been prioritised for actions based on current evidence and the potential actions that could be put in place. Langford Brook has now been assessed as being at Good Ecological Status. Further biological monitoring will be taken to ensure the river does not deteriorate by To get involved with work in the catchment please contact: Catchment host LouisePrint-Lyons@BBOWT.Org.UK OR For more information on the issues, classifications or for specific evidence for this catchment please contact: EA Catchment contact Mark.Barnett@Environment-Agency@Gov.UK All maps in this document are based on Ordnance Survey Landline data and produced for the Environment Agency with the permission of Ordnance Survey. Aerial imagery is copyright Get mapping plc, all rights reserved. Licence number Crown copyright. All rights reserved. Environment Agency, , 2008.

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