Information and Advsiory Note Number 65, November 1996
1.1 Scotland has approximately 50,700 km of rivers (at 1:25,000 scale), 30,000 freshwater lochs (at 1:63.360 scale), and a sea area inside the 12 mile territorial limit of nearly 55,000 km2. Together, these aquatic environments constitute a resource of immense socio-economic, cultural and natural heritage importance.
1.2 All of these waters receive at least some inputs of human-generated waste materials, from atmospheric deposition, diffuse non-point sources, direct point-source discharges and accidents. Rivers, some standing waters, estuaries and coastal waters have traditionally been used for the disposal of sewage, agricultural and industrial wastes. Such discharges have only received serious attention and pollution control efforts in the last few decades. The improvement of water quality in urbanised rivers such as the Clyde has attracted much public attention, largely through the return of the long-absent salmon. Other pollution incidents in Scottish waters, such as the seepage of crude oil into the North Sea following the sinking of the tanker Braer, have received international interest.
1.3 Responsibility for pollution control and the licensing of discharges to Scottish waters lies with the Scottish Environment Protection Agency (SEPA). SEPA has a duty to consult SNH over proposed discharges which are likely to have an effect on some natural heritage interests. This Note sets out the legislation and procedures by which water pollution control is achieved in Scotland, and provides information for SNH staff dealing with consultations over discharge consent applications. Consents are most frequently applied to rivers, and the licensing procedure is very similar to the local planning process in terms of statutory timescales, etc. (Figure 1). The range of polluting substances likely to be encountered in effluent discharges entering Scottish waters is presented in Table 1.
2.1 Over the past 30 years, water pollution control has been undertaken by the seven river purification boards and three islands councils (collectively referred to as the river purification authorities (RPAs)). In April 1995, the former RPAs, Her Majesty’s Industrial Pollution Inspectorate, the waste regulation and local air pollution services of the councils, and some duties of the Hazardous Waste Inspectorate became combined under a single management structure. This has integrated the regulation of emissions to air, land and water from industrial processes by one national agency: SEPA; its responsibilities are set out in the Environment Act 1995.
2.2 Integrated Pollution Control (IPC) has been introduced by part 1 of the Environmental Protection Act 1990. The recently introduced EC Integrated Pollution Prevention and Control Directive extends the scope of the UK IPC legislation. Discharges from industrial plant are authorised by SEPA, where a single written authorisation for a particular process is granted covering all three environmental media. These authorisations are based on best available techniques not entailing excessive cost (BATTENS). An authorisation has two main functions:
If a discharge to controlled waters is not acceptable, the IPC licence may be granted if an improvement timetable is agreed.
2.3 EC Directives (Table 2) have established environmental quality standards (EQSs) for particular uses of water. EQSs limit pollution by setting emission limit values for the most dangerous ‘black list’ substances. The UK’s approach to discharge control has been based on the attainment of environmental quality objectives (EQOs) for the receiving water. A framework Directive on dangerous substances (76/464) allows a compromise in approach by establishing both limit values and quality objectives.
2.4 SEPA’s water pollution control powers mainly stem from the Control of Pollution Act 1974 (COPA) as amended by Schedule 23 of the Water Act 1989 and the Environment Act 1995. COPA provides a duty for the relevant authority to promote the cleanliness of inland waters, groundwaters, estuaries and coastal waters. The powers of COPA to set discharge consent conditions are relied upon for the implementation of water quality standards and objectives that are set by various EC Directives. To comply with the Directives, the Water Act 1989, amended by the Water Resources Act 1991, established statutory water quality objectives (SWQOs) for controlled waters. These objectives are a legal tool for setting and achieving water quality targets for specific catchments and by specific dates. As yet, SWQOs are only being established on a pilot scale in England and Wales, and none are proposed for Scotland.
3.1 The Environment Act 1995 requires SEPA to have regard to the desirability of conserving and enhancing the natural heritage when considering the effect of a development proposal. As a general duty, separate from the rest of its functions, SEPA is to promote, as it considers desirable, the conservation of flora and fauna which are dependent on an aquatic environment. Under the same Act (Section 35), SNH has supplied SEPA with details of all SSSIs, in order to allow SEPA to assess whether a proposal is likely to damage the interests of a SSSI and, if so, to consult SNH over the proposal. Under the ‘Habitats Regulations’ 1994, SEPA, as a competent authority, should have regard to the requirements of the EC ‘Habitats Directive’ in exercising any of its functions. Under this Directive, SEPA also has specific duties to assess the effects of discharge consents on European sites.
3.2 These new statutory requirements strengthen the existing Scottish Office voluntary code of practice on conservation, access and recreation. SEPA has been given clear duties and guidance that it should go as far as is reasonable to protect the natural heritage when fulfilling its statutory duties with regard to the assessment of discharge consent applications. In reality, SEPA staff may look to their local SNH staff to provide guidance on the likely impacts of any proposal on natural heritage interests.
3.3 In making an assessment of the likely impacts of aquatic pollution, the following natural heritage interests should be considered:
3.4 There are also clear opportunities for SEPA to promote natural heritage enhancement, e.g. use of reedbeds in surface water run-off and sewage treatment.
4.1 Since both SEPA and SNH have a statutory remit for the sustainable use and management of the natural environment, it is sensible for the two organisations to agree a way of co-ordinating common and complementary activities. A Memorandum of Understanding (MoU) was signed by the Chairmen of both organisations in August 1996. The MoU sets out a framework ensuring that both SEPA and SNH are committed to co-operation, that each is aware of the objectives and responsibilities of the other, and that where there is a common interest the demands are not conflicting. With regard to discharges to the aquatic environment, this should lead to improved co-ordination over casework involving the protection of sites and species from aqueous pollution.
5.1 Under Section 34 of COPA anyone discharging to controlled waters must apply for a consent from SEPA. Having a consent for a discharge and complying with it is a defence against committing a statutory pollution offence. The applicant must provide full details of the proposed discharge to SEPA, which advertises significant discharges and copies the application to the local authority.
5.2 Application forms for discharge consent are also designed to remind the discharger to inform SEPA of any changes to effluent or site conditions so that existing consents can be amended, where necessary, to continue protection of the receiving waters.
5.3 When SEPA receives a discharge application it has to answer a number of questions before making a decision on whether to license the discharge and, if so, what conditions to set. Questions SEPA will consider include:
5.4 In framing a consent SEPA must balance three main points:
In addition, SEPA must take into account the likely effects of any new or altered discharge on the natural and built heritage. This assessment must be balanced against the social and economic needs of the area in which the discharge is proposed. Generally the consent will be issued subject to conditions which may refer to the location, design and construction of the discharge outlet, the volume of the discharge, the concentration and loads of particular components in the discharge, and arrangements for taking samples of the discharge. Some types of discharge may require a toxicity condition in which case the appropriate test method will be prescribed on the consent at the time of issue. Charges are made by SEPA for processing a discharge consent application, for subsequent monitoring and any enforcement activity.
Due to the ways in which limits can be expressed and the complexity of effluents, there are three main categories of discharge consents:
6.1 Numeric consents relate to discharges for which numeric limits are specified for the flow and for concentrations of one or more constituents (also referred to as determinands). These consents are often monitored and continuously sampled.
6.2 Non-numeric consents apply to discharges where numeric limits may be set for flow but not for the determinands. These conditions often relate to the technical requirements of the process which the effluent passes through, e.g. storm overflows.
6.3 Descriptive consents are a sub-group of non-numeric consents and usually relate to smaller discharges of little or no significant environmental impact, e.g. very small sewage works. This does not devalue their importance or the need for dischargers to comply with the consent.
7.1 The aim of the discharge consent is to control the polluting load of the effluent. This calls for various limits to be set.
7.2 Load is the amount of material per unit time being carried by the discharge. In practice, the load of a discharge is established from direct measurements of flow and determinand concentration. Limits on loads are often applicable to effluents which are accumulative or which have long residence times due to the poor dispersion conditions in the receiving water.
7.3 Absolute limits (maximum limits) apply to most numeric consents, where it is an offence to exceed the limit set. However, in practice it is regarded as satisfactory if compliance is met 75% of the time. Absolute limits constrain peak discharges.
7.4 Percentile limits control the routine operating levels of discharges and require a time-period reference. Modelling techniques are used to evaluate the continuous variability in effluent quality, and give a statistical distribution of required effluent concentrations. Percentile limits (expressed as 95% or 99.5%) prevent dischargers from operating just under the absolute limit, control the cumulative impacts of the effluent, and provide a safeguard against possible non-conformity with the absolute limit.
8.1 Once SEPA has issued a consent for a new or altered discharge, it monitors the quality of the effluent in order to ensure that it meets the required standards. Effluent samples are collected and analysed routinely, the frequency depending on the size and importance of the discharge. Larger urban sewage treatment works may be sampled weekly or monthly, while small sewage treatment works may be inspected only once or twice a year.
Chemical biological monitoring
8.2 In addition to routine effluent sampling, SEPA also has a programme of routine water quality sampling of the receiving water. Chemical and biological samples are collected from rivers, some standing waters, estuaries and some areas of coastal waters. Chemical sampling leads to an indication of the condition of the river at the time of sampling, and can identify particular polluting compounds (if included as part of the chemical sampling programme). Biological samples are usually of benthic macroinvertebrates - insect larvae, crustacea, snails, worms, etc. - and can indicate the condition of the river at the moment of sampling and in the recent past. Biological sampling can also allow for tracing pollution to otherwise undetected sources, and indicate forms of pollution not routinely chemically analysed. The bacteriological quality of coastal water is also monitored for compliance with the EC Directives on bathing water and shellfish.
8.3 The main purpose of all these routine monitoring programmes is to ensure that the overall quality of the aquatic environment is maintained, i.e. that licensed discharges are not leading to an unacceptable degradation in aquatic environmental quality. There is an added benefit in that this environmental monitoring often leads to the detection of previously undetected pollution sources, such as chronic leaks from farm waste storage facilities, or severe impacts, such as spillages of agricultural pesticides into watercourses. The collected data also contribute to long-term monitoring of trends in water quality parameters.
9.1 Records of discharge consents and effluent monitoring are maintained by SEPA on a public register. Registers are open for public inspection. There is no charge made for inspection of the records.
9.2 SEPA publishes summaries of all its monitoring data on an annual basis. More detailed information may be obtained from SEPA offices.
10.1 SEPA operates a 24 hour call-out service to allow an immediate response to pollution incidents. Pollution prevention staff normally attempt to track down the source of the pollution, if possible. They will then take what steps they can to prevent further pollution from that source. This might be by contacting the appropriate landowner, manager, or other person responsible for the polluting facility, or more directly by, for example, deploying oil pollution prevention equipment (e.g. booms, oil-absorbent pads, etc.) following a spill or leak of oil to a watercourse.
To a large extent point-source pollution (from pipelines, etc.) is well controlled in Scotland, but diffuse-source pollution (e.g. nitrates leaching from agricultural land, sedimentation as a result of forestry activities, etc.) remains difficult to legislate against and control.
10.2 There are four main sources of diffuse pollution which pose a threat to Scottish fresh waters:
The options for statutory control of such sources are limited.
10.3 SEPA staff work pro-actively with farmers, local authorities, private landowners, industrial and commercial concerns, providing advice on improvements in existing pollution control facilities. Practical guidance is available to help land users to avoid causing pollution to watercourses, such as the Code of Good Practice for the Prevention of Environmental Pollution from Agricultural Activity (SOAFD, 1993), and the Forests and Water Guidelines (Forestry Commission, 1994). EC Directives (e.g. the Nitrates Directive) are also proving useful since they tackle the important issue of land-use management as a method of limiting pollution.
11.1 Compliance monitoring provides factual evidence for the enforcement of pollution control legislation. Failure to comply with consent conditions is a criminal offence under COPA Section 30F. Fines may be up to £20,000 per day. SEPA is trying to prevent pollution by promoting rapid remedial action and the provision of better treatment facilities. Therefore a breach of consent is not automatically reported to the Procurator Fiscal for consideration as to whether a prosecution is appropriate.
11.2 Where there is a risk of pollution from activities not covered by licensing, regulation may be achieved through prohibition notices. Such activities include:
The extent of risk from pollution determines whether SEPA makes a conditional or absolute prohibition notice. Notices are issued on a case by case basis, and provide the opportunity to consult with SNH. Where no pollution risk is perceived, SEPA advocates pollution control by best management practices (BMPs) through the planning application process.
Pollution events which are not controlled by the consent procedure constitute an offence under COPA Section 30F. Section 31A makes provision for pollution prevention through measures such as the Control of Pollution (Silage Slurry and Agricultural Fuel Oil) (Scotland) Regulations 1991. Such Regulations allow SEPA to order operators to take remedial measures to address the risk of pollution, and failure to comply constitutes an offence.
11.3 Where the powers of enforcement are limited, education and persuasion are necessary. Co-operation between relevant agencies, such as SNH, offers a means of providing more pre-emptive action. SEPA also seeks to influence planning authorities to encourage land zoning and planning policies which promote sustainability and are complementary to water quality objectives.
Forestry Commission 1993. Forests and Water Guidelines. HMSO, Edinburgh.
Haslam, S. M. 1990. River Pollution: an Ecological Perspective. Belhaven Press, London.
Howell, D. L. 1994. Role of Environmental Agencies. In The Fresh Waters of Scotland. A National Resource of International Significance. Maitland, P. S., Boon, P. J. and McLusky, D. S. (Eds), 577-612. John Wiley, Chichester.
Laws, E. A. 1991. Aquatic Ecology: an Introductory Text (2nd Ed.). John Wiley, Chichester.
Mackay, D. W. 1994. Pollution Control. In: The Fresh Waters of Scotland. A National Resource of International Significance, Maitland, P. S., Boon, P. J. and McLusky, D. S. (Eds), 517-530. John Wiley, Chichester.
Scottish Office 1993. Conservation. Access and Recreation - Code of Practice for Water and Sewerage Authorities and River Purification Authorities. HMSO, Edinburgh.
Scottish Office Agriculture and Fisheries Department 1993. Code of Good Practice for the Prevention of Environmental Pollution from Agricultural Activity. HMSO, Edinburgh.
SEPA local offices (contact Erskine Court for details)
Nikki Wood, SNH
Scot Mathieson, SEPA