Watercourses and associated corridors

NE2: Watercourses and associated corridors 1. Development is required to conserve and enhance the functions and setting of any affected watercourse and associated corridor through good design, including in terms of biodiversity, landscape, flood management and recreational/amenity value. 2. Opportunities for de-culverting and re-naturalising watercourses and removing fish passes shall be actively pursued where development sites contain or are adjacent to watercourses. Where this is clearly demonstrated not to be possible, s106 contributions will be sought to help enable enhancement works on areas of a watercourse in the vicinity. Contributions will be commensurate to the de-culverting or re-naturalising opportunity that could not be taken. 3. Proposals will only be supported where they do not involve the canalising or culverting of watercourses and do not prejudice future opportunities for de-culverting / renaturalising. 4. Development proposals for new development adjacent to or containing a watercourse are required to provide or retain at least a 10 metres natural buffer between the top of the watercourse bank and the development, with no lighting, and include a long-term landscape and ecological management plan (or habitat management and monitoring plan) for this buffer. Where the watercourse is a Chalk Stream or a ditch connected to a chalk stream, as listed in this policy, this natural buffer must be at least fifteen metres. 5. Chalk streams (including headwaters) (as indicated in the Local Nature Recovery Strategy Mapping) in Buckinghamshire are: a) Hamble Brook b) Hughenden Stream c) River Chess d) River Misbourne e) River Wye f) River Colne g) Alderbourne h) Escarpment chalk streams 6. A long-term management plan must be in place for the watercourse and its buffer zone within the control of the development including the management of invasive nonnative species. The management plan must be in accordance with the river catchment management plan (and other more specific plans) In new developments, publicly accessible space must be designed to include existing watercourses to ensure adequate access for maintenance of the watercourse. 7.146 Policy NE2 emphasises the importance of conserving and enhancing watercourses, as part of improving the wider water environment (see also policy NE1 on water quality). Watercourses and their associated corridors are a vital element of the Green and Blue Infrastructure of Buckinghamshire. They have several valuable functions – as a landscape and amenity feature, for biodiversity as a habitat and as a corridor to allow movement of species, for flood management, for recreation, as a water resource and to allow access for river maintenance. Enhancements and improvements to river habitats and their buffers will provide resilience to climate change. 7.147 In terms of 5 (g) Escarpment chalk streams are found along the north-west facing side of the Chiltern Hills. They are fed by groundwater and originate along the spring-line at the base of the Chiltern escarpment. The spring-line occurs where the Chalk aquifer discharges at the junction with underlying or adjacent less permeable strata (notably the Upper Greensand and Gault Clay). 7.148 The Local Nature Recovery Strategy mapping identifies the location of chalk streams and rivers in Buckinghamshire. It does not show sections of streams and rivers which are underground due to culverting, however this policy does apply to underground sections. 7.149 This policy covers Main Rivers (as defined by the Environment Agency), ordinary watercourses, and canals. Ordinary watercourses are any channel / passage of water through which water flows, which do not form part of a Main River. They can include streams, ditches, drains, mills, dams, culverts and weirs. 7.150 Of particular importance in the county are the River Wye, River Chess, River Misbourne, River Colne, Hamble Brook, Alderbourne and their tributaries as these are chalk streams which are a globally rare habitat that has been designated as a priority habitat within the UK Biodiversity Framework. Additionally, the River Thames has a nationally important landscape value. 7.151 Opportunities for the built environment involving watercourses include creating attractive places where people want to live, work and play through making space for water and green spaces in the built environment. They can also provide cost-effective infrastructure that uses fewer natural resources and has a smaller whole-life carbon footprint. One of the aims of the policy is to help create developments that are more able to cope with changes in climate, protecting people and property from increased flood risk from climate change. 7.152 Some watercourses have been altered in some way by either straightening the channel, replacing natural banks with hard engineering, dredging or widening. These changes over time have led to the loss of natural features such as bankside habitats, gravel riffles, pools and meanders, and in many cases, banks have been increased in height, disconnecting the watercourse from its floodplain. 7.153 Developments which contain or are adjacent to watercourses offer an opportunity to provide ecological buffers, restore bankside and in-stream habitats, create pond complexes and natural floodplains. Carefully designed developments along watercourses can increase the ecological and biodiversity value of the features within them, and the value of the overall development. 7.154 Canalising is the use of hard engineering (including walls, piles, gabions and plastic geo-bags) to create structure instead of more natural riverbank. 7.155 Developers will need to refer to the detailed Lead Local Flood Authority (LLFA) information on the website regarding responsibilities and requirements for Consents / Permits prior to work on any watercourse being undertaken. Early engagement with the LLFA should also be pursued for works in and around ordinary watercourses. https://www.buckinghamshire.gov.uk/environment/flooding-and-flood-risk-management/ 7.156 The policy requires a 10m buffer (except for chalk streams – see below). Where the watercourse flows through a development site, the buffer is required on both sides of the channel. This width of buffer provides the minimum width of habitat needed to provide for the functioning of wildlife habitats, while being able to facilitate informal access for enjoyment of the river (see VALP watercourse advice note on the website for more details). This width also ensures that the river is buffered from land-based activities, e.g. reducing the levels of diffuse pollution reaching the watercourse. Furthermore, this buffer allows for ease of access for maintenance of the watercourse to ensure flood risk is not increased due to lack of maintenance and/or blockage. Developers are encouraged to engage early on with the council to understand what is appropriate for inclusion within the buffer strip. The buffer zone is also a riparian zone highlighting its importance for biodiversity and habitat. 7.157 Development can enable good opportunities to increase public access to rivers and riverbanks. Increasing public access provides a great opportunity to engage the public and connect people with nature. This should be achieved in an environmentally sensitive manner to ensure biodiversity is not adversely affected by human activity. 7.158 Buffer zones should be of natural character, free from built environment (including paths, roads, residential gardens and play areas), with no light pollution greater than two lux and a warm white’ colour temperature of 2700k or less (see also policy NE10 Mitigating light impacts). 7.159 The importance and vitality of chalk streams to Buckinghamshire's Chilterns Landscape cannot be underestimated. Chalk rivers and their ecosystems provide a unique habitat for fish, animals and plants. Healthy chalk streams are the most biodiverse of rivers. They face increasing pressure from climate change, population growth and development, pollution and abstraction. Ensuring no further deterioration from current baselines involves affording them stronger policies for their protection. 7.160 Within the Chilterns National Landscape and it is setting please also see the Chilterns Chalk Streams Planning Guidance (2025 as replaced). This guidance offers a way forward; a set of practical recommendations for planners, developers, and communities to ensure these precious rivers are properly considered and protected in the planning system. 7.161 Chalk-stream ecological health depends on three factors. a) water quantity (the naturalness of the flow regime) b) water quality (how clean the water is) c) physical habitat quality (the physical shape of the river, but incorporating biological factors like invasive species which can degrade habitat directly and indirectly) 7.162 Chalk streams are also highly dependent on the geomorphology and biodiversity of the riverbank, necessary to maintain the condition of the chalk habitat and the species it supports. As a result, a wider buffer of a minimum of fifteen metres is required for designated Chalk streams and their headwaters. This zone should extend further than 15m where necessary in line with the natural flood plain. Where development is proposed in areas close to modified chalk streams, planning can help to seek to return the river to a more natural state. Other consents/ permits from the relevant authorities will still apply. 7.163 Opportunities to expand ecological buffers, corridors or stepping stones such as existing riparian vegetation that link up with existing green infrastructure should be maximised. 7.164 The policy requires a Water Framework Directive assessment where development could have an adverse impact on the water body. This is because development adjacent to watercourses are expected to contribute to achieving the Water Framework Directive objectives. River Basin Management Plans are a tool used to deliver the WFD objectives and Buckinghamshire Council; water companies and developers have an obligation to have regard to such plans.