Buckinghamshire & Milton Keynes Biodiversity Action Plan Rivers and Streams Habitat Action Plan
Rivers and Streams
Key associated species
Bittern Pipistrelle Black Poplar Reed Warbler Brook Lamprey River Water Dropwort Bullhead Sedge Warbler Depressed River Mussel Spined Loach Daubenton’s Bat Teal Flowering Rush Water Vole Freshwater Pea Mussel Whiskered Bat Kingfisher Freshwater White-clawed Crayfish Otter
Rivers and streams are dynamic systems, continually modifying their form. However within Buckinghamshire their ability to evolve has been much reduced or arrested by flood defence structures and impoundments. Historically, unsympathetic engineering schemes have been responsible for destroying many riverine habitats, lowering water levels and water tables in the surrounding land.
Lowland, nutrient-rich streams support a thriving ecology, including a range of invertebrates, fish, mammals and birds. They are dominated by higher plants, but where nutrient levels are artificially high the occurrence of algae increases. Rivers are more than just conduits for water, with a range of associated in-channel and riparian habitats that may include shingle and gravel beds, riffles and pools, earth banks, eroding cliffs, silt bars, islands, reedbeds and overhanging trees.
Rivers provide a wide range of functions including the supply of water, sewage disposal, the drainage of flood waters and they act as areas for leisure and recreation. Rivers and streams are systems capable of self- regulation but it is vital that they are managed in a sympathetic manner so they may fulfil their ecological potential. It is also important to recognise that if river catchments are to be managed sustainably, floodplains must also be considered as an essential component of the river environment
The draft criteria for BAP Rivers in the England Biodiversity Strategy that are relevant to Buckinghamshire and Milton Keynes are as follows;
1. Headwaters 3. Chalk Rivers as given in the existing BAP definition. (see seperate HAP for Chalk Rivers) 7. Species – detailed quantitative guidance is under development in 2008 and will cover: a. Occurrence of Annex II Habitats Directive species
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b. BAP priority species
Disqualifying feature 9. Reaches which are heavily degraded and which have little scope for improvement, for example because they are heavily canalised, will not be considered for inclusion as BAP priority habitat.
1 Current status in UK
Biological status
1.1 Rivers and their floodplains in their natural state are dynamic systems continually modifying their forms. They can encompass a great variety of habitats for wildlife and provide important wildlife corridors. Rivers and streams are also valued for fisheries and as significant landscape and historic features.
2 Current status in Buckinghamshire
Cover and distribution
2.1 Buckinghamshire encompasses part or all of four distinct river catchments: the River Thame, River Wye, River Colne and Upper River Great Ouse totalling 1,600 km of rivers and streams within Buckinghamshire, all of importance for wildlife.
2.2 The watershed between the Thames and the Great Ouse catchments lies between Aylesbury and Buckingham with a network of streams and springs draining these catchments. These include the Ouzel and the Claydon Brook in the north, the Thame and Ray in the Vale of Aylesbury, and the Colne, Chess and Misbourne and Wye of the Chilterns and South Buckinghamshire.
2.3 The Environment Agency has undertaken river corridor surveys of most of the Statutory Main Rivers in Buckinghamshire.
Relatively unmanaged rivers have a diverse physical structure with pools, riffles, secondary channels, backwaters, fringing marshes and floodplain woodland. The high diversity of river and floodplain habitats results in a corresponding diversity of wildlife.
Trends
2.5 Historical demands to protect people and property from flooding, and improve agricultural land have resulted in a legacy of insensitive land drainage and flood defence in the UK. Such works tended to degrade the ecological value of the river channel and hydrologically isolate the river from its floodplain, resulting in habitat loss for wildlife. However, a more integrated approach to rivers and their floodplains has been
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developed by the Environment Agency through Local Environment Agency Plans (LEAPs),addressing pressures such as urban and rural land use and development, water management and recreation. An overall improvement in water quality and restoration and enhancement of riparian habitats over the last 10 or more years has resulted in the return and recovery of many species.
River management now falls under the Water Framework Directive, with the production of River Basin Management Plans which cover all aspects of river basin management.
3 Current factors affecting the habitat 4 Pollution 3.1 Discharge of effluent arising from sewage treatment works, industry and agriculture, including point and diffuse sources, leads to high nitrate and phosphate levels, causing eutrophication and acidification.
Abstraction 3.2 Excessive ground water and surface water abstraction, results in low flows and reduced dilution of pollutants.
Loss of riverine habitats and floodplain 3.3 This can include artificial channel modification, construction of dams and reservoirs, insensitive land drainage and flood defence works.
Inappropriate land use and bank management 3.4 This can include intensive agriculture and overgrazing which leads to a deterioration in habitat quality.
Invasive species 3.5 Invasive plant and animal species can be introduced or arrive naturally.
Climate change 3.6 This may result in different hydrological regimes and extreme environmental effects.
Development 3.7 Industrial, housing and hydroelectric power scheme development within the floodplain.
Recreation 3.8 This can lead to loss of habitat quality through disturbance and erosion eg through high levels of boat use.
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4 Current action
Legal status 4.1 The Environment Act came into force in 1995. Under this Act, the Environment Agency has two primary statutory duties in respect of conservation interest.
* To further, wherever possible, conservation when carrying out water management functions. This also applies to Freshwater Fisheries Act 1975, Land Drainage Bylaws and Water Resources Act 1991, and licensing functions.
* To have regard to sites of special conservation interest when carrying out pollution prevention and control functions.
4.2 In fulfilment of these duties the Environment Agency seeks to conserve and enhance the water environment when carrying out all its regulatory and advisory activities.
4.3 As a statutory planning consultee, the Environment Agency also applies these duties and a free-standing duty, generally, to promote the conservation of natural beauty and amenity, and the wildlife dependant on the aquatic environment, to seek to influence structure plans, major development and individual planning applications.
4.4 The Conservation (Natural Habitats etc) Regulations 1994 state the importance of rivers and other linear features as wildlife habitats and mechanisms for dispersal. As such their protection and management is encouraged. This is also recognised in PPS 9 Biodiversity and Geological Conservation.
4.5 Nitrate Vulnerable Zones cover the whole of the county except for most of South Bucks (the Thames and Colne are covered) and the area west of High Wycombe around Cadmore End and Ibstone. These place certain restrictions on the use of nitrogen fertiliser on farmland and are designed to help reduce the levels of nitrate in rivers and aquifers.
Management, research and guidance
4.6 The range and type of natural habitats found in rivers are determined largely by fluvial processes. As water works its way downstream, energy is expended on the transportation and re-arrangement of materials in the river channel and floodplain. Meanders can migrate, banks may erode, new channels form and old ones cut-off, creating backwaters. An understanding of fluvial geomorphology is essential if such habitats are to be safeguarded or re-created.
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4.7 In the modified river it is the range of remaining natural habitat features which dictate its wildlife potential and it is these which may be degraded or enhanced by management.
4.8 River and floodplain habitat in its unconfined natural state is characterised by a continuum of habitats, from the flowing main channel to aquatic, semi-aquatic and terrestrial environments. In- channel riffles are spawning areas for fish species, gravel bars may support a wide range of invertebrates, eroding bankside cliffs provide nesting locations for a range of birds, channel margins, backwaters and lowland wet grassland are particularly valuable habitats for wetland plants as well as other wildlife.
4.9 Restoration and enhancement of degraded rivers can be achieved by recreating natural river features, allowing natural dynamic river processes to occur and restoring the river’s connectivity with its floodplain.
4.10 Following approval by the DETR of the Environment Agency’s submission for the National Environment Programme of improvements of the water companies, the latter’s Asset Management Plan (AMP3) for 2000-2005 contains a comprehensive programme of improvements to performance for sewage treatment works and for the resolution of problems associated with over-abstraction
5 Objectives
5.1 It is important that Habitat Action Plan objectives and actions are considered in conjunction with those in Generic Issues (see Generic Issues). All Generic objectives and actions apply to each individual Habitat Action Plan.
6. Biodiversity Opportunity Areas
The following Biodiversity Opportunity Areas are likely to identify Rivers and Streams as a priority habitat.
• Bernwood • Claydon and Padbury Streams • Colne Valley • Milton Keynes City • Ouse Valley • Ouzel Valley • South Bucks Heaths & Parklands • Thame Valley • Thames Valley • Upper Ray
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National Target Code Target Action Start End Action location Lead Other Orgs Nume Baseline ric Units RS1 Achieve good ecological status for rivers and streams RS1/1 Identify critical sections of river habitat 2007 2010 Aylesbury Vale AVDC X ha X in Aylesbury Vale and notify as Local Wildlife Sites RS1/2 Identify critical sections of river habitat 2007 2010 Milton Keynes BMKB X ha X in Milton Keynes and notify as Local P Wildlife Sites RS1/3 Identify critical sections of river habitat 2007 2010 South Bucks BMKB X ha X in South Bucks and notify as Local P Wildlife Sites RS1/4 Identify critical sections of river habitat 2007 2010 Wycombe BMKB X ha X in Wycombe and notify as Local Wildlife P Sites RS1/5 Protect and improve the quality of water Bucks & MK EA in the county by developing a macrophyte and macroinvertebrate monitoring programme to implement the requirements of the Water Framework Directive RS2 Restore river and stream habitats RS2/1 Identify, develop and implement river 2007 2010 Aylesbury Vale TBC X ha X and stream habitat restoration and enhancement in Aylesbury Vale RS2/2 Identify, develop and implement river 2007 2010 Milton Keynes TBC X ha X and stream habitat restoration and enhancement in Milton Keynes RS2/3 Identify, develop and implement river 2007 2010 South Bucks TBC X ha X and stream restoration and enhancement in South Bucks RS2/4 Identify, develop and implement river 2007 2010 Wycombe TBC X ha X and stream restoration and enhancement in Wycombe RS3 Ensure best practice environmental management guidelines are implemented on all
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rivers and streams RS3/1 Advise on river margin options in the 2007 2010 Bucks & Milton FWAG X sites X consultation process of Environmental Keynes Stewardship applications
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