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Home , Chalk stream, River Misbourne, Winterbourne (stream)

Buckinghamshire & Biodiversity Action Plan Habitat Action Plan

Chalk Rivers

Key associated species

Bewick’s Swan Water-crowfoot Brook Lamprey River Water-dropwort Snipe Bullhead Spined Loach Cetti’s Warbler Water Crowfoot Grayling Water Rail Green Sandpiper Water Shrew Kingfisher Water Vole Otter Freshwater White-clawed Crayfish Reed Bunting

Chalk rivers are amongst the most species-rich and productive riverine habitats and have a characteristic plant community often dominated in mid- by River Water-crowfoot species and Starworts, with and Lesser Water-parsnip along the edges. Such habitat provides suitable sites for a rich diversity of invertebrate life and provides important fisheries, with low banks also supporting a range of water-loving plants and associated fauna.

All chalk rivers are fed from and in order for them to maintain their flow, adequate winter rainfall is needed to recharge the . In winter when more percolates down into the aquifer the source of the river will be higher up the . In summer, as the drops, so the source of the river moves back down the valley. These stretches of the with intermittent flow are known as ‘winterbournes’. A number of specialised invertebrates and plants are adapted to such conditions. Calcareous fen communities and carr woodland occur within the river corridor of chalk streams where these have not been lost to intensive agriculture or development.

The characteristics of chalk streams can be summarised thus: y they are fed primarily from groundwater y the temperature of the water does not vary greatly throughout the year (2-3 degrees max) as it comes from the ground y they have a high biodiversity y they are not generally liable to flash flooding as they are little affected by direct rainfall y the source of the river will move up and down the valley through the seasons y they generally have very clear water, filtered by its passage through the chalk and bed.

1 & Milton Keynes Biodiversity Action Plan Chalk Rivers Habitat Action Plan

1 status in UK

Biological status

1.1 The soft, calcareous, porous rock known as chalk only occurs in , France and New Zealand. In England it is found in hills (downs) and plains within a crescent extending from , through Kent, Buckinghamshire and to Norfolk and East Yorkshire. The smaller rivers rising from this rock are known as chalk streams. As a result of a combination of climate, geology and human activity, they have several characteristic features, which encourage plant and animal life and make them unique.

1.2 Chalk streams are internationally important and are listed in Annex I of the European Habitats Directive as ‘floating vegetation of Ranunculus of plain and submountainous rivers’. England has the majority of this resource in Europe and therefore has special responsibility for the conservation and enhancement of chalk streams systems. This status was reflected in the UK Biodiversity Steering Group Report, which prioritised chalk rivers as a key habitat. The 2007 Habitats and Species Review proposed that rivers be defined as a UK BAP Priority Habitat with the inclusion of Chalk Rivers within this wider definition. However the Chalk Rivers in Buckinghamshire are considered such a priority for the county Biodiversity Action Plan that the separate Chalk Rivers HAP has been retained.

1.3 The characteristic plant community of chalk streams is often dominated in mid-channel by Water-crowfoots and Water-starworts, whilst Watercress and Lesser Water-parsnip grow along the edges. They have low banks which support a range of water-loving plants. The adjacent riverside habitats are often of considerable value for wildlife. Wet meadows may provide areas of species-rich grassland and are particularly important for breeding birds such as Redshank and Snipe.

1.4 All chalk streams are fed from groundwater , producing clear waters and a generally stable flow and temperature regime. These conditions and the gravel substrate support a rich diversity of invertebrate life and important fisheries, notably for brown trout. Brook Lamprey, Salmon, Freshwater White-clawed Crayfish and otter are among the species listed on Annex II of the EC Habitats Directive that chalk streams support. Most chalk streams have stretches in their headwaters. These often run dry, or partially dry, in late summer because of lack of rainfall recharging the aquifer. A characteristic range of invertebrates has adapted to these conditions, as has the pond Water-crowfoot.

2 Buckinghamshire & Milton Keynes Biodiversity Action Plan Chalk Rivers Habitat Action Plan

2 Current status in Buckinghamshire

Cover and distribution

2.1 The chalk streams of the Chilterns are an important component of the wildlife resource of Buckinghamshire. The river valleys contribute a great deal to the character and quality of the Chilterns landscape and they support distinctive wildlife communities. Buckinghamshire has a number of chalk streams running to the south of the Chilterns, namely: , , River Wye, and Hughenden .

Trends 2.2 Since forest clearance around 1000 BC, chalk streams have been heavily influenced by human activities. The Romans and Saxons started building water mills. Impoundments on the streams resulted in localised decreases in gradient and stream flow energy, resulting in siltation and a reduction in dissolved oxygen. They also caused a problem for the passage and migration of aquatic invertebrates and fish. Drainage of the fields in the valley bottoms reached a climax between 1650 and 1900 in the elaborate system of water meadows. As the population of the valleys increased, human and animal affected the chalk rivers (today it is mostly discharged as well-treated ), increasing the amount of phosphorus entering the water.

2.3 Intensive agriculture in conjunction with drainage has destroyed wetlands and degraded the river corridor and has led to increased nutrients and within the rivers. Urban pressures can lead to reinforcement and the loss of river corridor. Modification of the temperature, mineral and organic content of the water will affect plant and animal life as will the introduction of non-native species such as and signal crayfish. More and more subterranean water is abstracted from the chalk for human use, which has sometimes reduced the flow.

3 Current factors affecting the habitat

Pollution 3.1 of arising from sewage treatment works, industry and agriculture, including point and diffuse sources, leads to high and phosphate levels, causing eutrophication and acidification.

Abstraction 3.2 Excessive ground water and abstraction, results in low flows and reduced dilution of pollutants.

Loss of riverine habitats and 3.3 This can include artificial channel modification, construction of and , insensitive land drainage and defence works.

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Inappropriate land use and bank management 3.4 This can result from intensive agriculture, overgrazing and allowing cattle uncontrolled access to banks.

Insensitive fisheries management 3.5 Poor management can lead to reductions in native animal and plant populations. Invasive species 3.6 Invasive plant and animal species can be introduced or arrive naturally and result in a loss of habitat quality.

Climate change 3.7 This may result in different hydrological regimes and extreme environmental effects.

Development 3.8 This may include industrial and housing development within the floodplain.

Recreation 3.9 Recreation can cause disturbance and and lead to a loss of habitat quality.

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.

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4.4 The Conservation (Natural Habitats etc) Regulations 1994 states 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 DOE PPG 9 Nature Conservation.

4.5 Agri-environment schemes can help to protect chalk streams. For example, in the Chilterns Area, Environmental Stewardship objectives include Arable Margins for the conservation of river valleys and chalk streams by provision of arable field margins to link and buffer existing wildlife habitats.

Management, research and guidance

4.6 Chalk streams have generally been subject to a long history of management and modification to meet a number of different needs such as fishing, cultivation of watercress and water supply. Consequently, there are no chalk streams in Buckinghamshire which could be considered to be wholly natural systems.

4.7 The construction of watermills and other structures has resulted in the creation of lakes and impounded sections, leading to a loss of the characteristics of a fast flowing with its abundant wildlife. Future management should aim to remove these man-made structures where possible.

4.8 Previous modification by dredging and poaching pressure from livestock has resulted in over-wide sections of stream, resulting in reduced flow velocities and silt . However, rehabilitation schemes to narrow over-wide sections are now occurring leading to restoration of the previous value of a fast flowing chalk stream.

4.9 Artificial of river channels for flood protection has resulted in loss of natural chalk stream habitat, particularly bankside and marginal habitats. Restoration and enhancement projects, such as restoring a natural channel or modifying artificial channels, increase the wildlife and amenity value of affected sections. For example, River Wye Project at Kingsmead Recreation Ground, .

4.10 Good fisheries management is compatible with nature conservation but sometimes the intensity of management can be detrimental. The Environment Agency and English Nature have produced guidance.

4.11 The Misbourne and Chess Valleys Project, set up in 1997 by the Chilterns Conference as a partnership between local authorities, water companies, voluntary organisations and the Environment Agency has carried out a wide range of work to enhance, interpret and promote the conservation of the chalk stream environment. Successes include in- stream and floodplain enhancement works on the River Chess, the

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production of interpretation and education material and promotion of the Misbourne Alleviation of Low Flows Scheme. This project, renamed the Chilterns Chalk Streams Project, is now expanding to bring benefits to other chalk streams in the Chilterns. It is anticipated that during 2000, a Chilterns Chalk Streams Officer will be appointed by the Chilterns Conference to work full time on chalk stream conservation.

4.12 The River Misbourne Alleviation of Low Flows Scheme, developed and implemented by the Environment Agency, Three Valleys Water and Thames Water, has led to a considerable reduction in abstraction in the Misbourne catchment. A 15 million litre per day reduction in abstraction will, combined with sufficient winter rainfall, create the necessary conditions for increased flow in the river.

4.13 The Environment Agency is currently progressing the River Wye Alleviation of Low Flows Scheme.

5 Objectives

5.1 It is important that Habitat Action Plan objectives and actions are considered in conjunction with those in Generic Issues. All Generic objectives and actions apply to each individual Habitat Action Plan.

6. Biodiversity Opportunity Areas

The following Biodiversity Opportunity Areas contain Chalk Rivers

• Central Chilterns Chalk Rivers • Chess Valley • Colne Valley • Hambleden and Wormsley Valleys

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National Target Code Target Action Start End Action Lead Other Targ Baseline location Orgs et total T2 - Achieve at least Good CR1 Achieve good Ecological Status or Good ecological staus, Ecological Potential for all high water quality chalk rivers (includes chalk and river SSSIs) by 2030 environmentally T6 - Achieve high water sustainable fish quality objectives for all communities in chalk rivers: GQA - chalk rivers 2000km achieve biological GQA class 'a' and chemical GQA grade 'A' by 2010 T10 - Achieve environmentally sustainable characteristic fish communities - 20% of chalk rivers achieving target by 2010 CR1/ Ensure that existing chalk river 2007 2009 Chiltern CCR CDC X X 1 Local Wildlife Sites in the P sites Chilterns AONB are in favourable condition CR1/ Undertake site visits and 2007 2010 Chiltern & CCR X X 2 provide specific guidance to Wycombe P visits fisheries managers CR1/ Identify obstacles to fish 2007 2010 Chiltern & CCR X X 3 migration and work with Wycombe P sites landowners and anglers to remove obstacles where appropriate CR1/ Establish a database of riparian 2007 2010 Chiltern & CCR X X 4 trees in the Chilterns AONB Wycombe P priorit

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and determine priorities for y management of existing trees sites and locations suitable for new trees CR1/ Monitor water vole populations 2007 2010 Chiltern CCR BBOWT 1 X 5 on the River Chess biannually P monit oring progr amm e CR1/ Monitor Brown Trout 2007 2010 Chiltern & EA 1 6 populations in the Chess and Wycombe surve Misbourne on an annual or 5 y year rolling programme CR1/ Review consents for utility 2007 2010 Chiltern & EA X 7 industrial / effluent discharge Wycombe cons where these are found to ents damage the quality of chalk revie rivers by 2010 (and implement wed necessary improvements by 2015) CR1/ Undertake biological monitoring 2007 2010 Chiltern & EA 1 8 of water quality in order to Wycombe monit produce BMWP score for each oring river progr amm e CR1/ Undertake chemical monitoring 2007 2010 Chiltern & EA 1 9 of surface and ground water Wycombe monit quality on all main river sections oring progr amm e T3 – Restore 150kms CR2 Restore chalk river chalk river habitat to high habitat

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quality physical status (RHS) (<30% graded poor) by 2010 T9 – Restore 3 chalk river wetland sites suffering from drying by 2010 CR2/ Identify, develop and implement 2007 2010 Chiltern & CCR CDC WDC X ha 0 1 at least one restoration Wycombe P programme per year CR2/ Complete River Restoration 2007 2010 Chiltern & CCR CDC WDC X 2 Plans for chalk streams to Wycombe P plans determine suitable sites for enhancement T4 - Ensure best practice CR3 Ensure best environmental practice management guidelines environmental are implemented on all management chalk rivers by 2015 guidelines are implemented on all chalk rivers by 2015 CR3/ Advise on river margin options 2007 2010 Chiltern & CCR FWAG NE X X 1 in the consultation process of Wycombe P advis Environmental Stewardship ory applications visits CR3/ Identify and designate chalk 2007 2010 Chiltern & BCC CCRP X 0 2 river sections as new Local Wycombe sites Wildlife Sites CR3/ Provide site specific 2007 2010 Chiltern & CCR BBOWT X 3 management advice to farmers Wycombe P visits and landowners along chalk rivers, particularly targeting water vole key areas CR3/ Hold an annual chalk river 2007 2010 Chiltern & CCR 1 4 forum in order to inform Wycombe P foru

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landowners and advisors on m management issues event T5 - Achieve ecologically CR4 Achieve acceptable target flow ecologically regimes for all chalk rivers acceptable target - 1000km chalk rivers flow regimes for all achieving ecological chalk rivers acceptable flows by 2010 CR4/ Monitor the need for further 2007 2010 Chiltern EA 1 reduction in abstraction on the Misbourne CR4/ Undertake regular chalk stream 2007 2010 Chiltern & EA X 2 flow measurements at Wycombe monit monitoring stations oring visits

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