« Previous | Contents | Next »
Listen
4. OVERVIEW OF DETAILED PROPOSALS
General surface water quality standards, water resource standards 2, morphological condition limits 3 and environmental quality standards for specific pollutants and priority substances play a key role in the management of the surface water environment. They describe the environmental conditions needed to support a particular ecological quality in surface waters, for example "high", "good", "moderate" or "poor" status.
The following sections provide additional information on the standards and condition limits for:
1. a second tranche of water quality (chemical and physicochemical) standards for surface waters comprising standards for:
(i) temperature in rivers;
(ii) phosphorus in freshwater and brackish lochs; and
(iii) nitrogen in transitional and coastal waters;
2. a second tranche of water resource standards and morphological condition limits for surface waters comprising standards or condition limits for:
(i) condition limits for river flows;
(ii) condition limits for freshwater flows into estuaries;
(iii) morphological conditions for freshwater and brackish lochs; and
(iv) morphological conditions for transitional and coastal waters;
3. environmental quality standards for 19 toxic pollutants (called "specific pollutants") being discharged in significant quantities into surface waters;
4. surface water environmental quality standards for pollutants identified as "priority substances" at European level 4;
5. biological standards for a range of plant and animal indicators of the status of surface water ecosystems;
6. threshold values for pollutants indicative of pressures placing bodies of groundwater at risk; and
7. an update to the 2007 Directions to include standards for "moderate" and "poor" to help differentiate the severity of adverse impacts where the standards and condition limits for "high" and "good" are not met.
4.1 SURFACE WATER QUALITY STANDARDS
This section deals with proposed standards for temperature in rivers, phosphorus in freshwater and brackish lochs and nitrogen in transitional and coastal waters.
Details of the technical work undertaken by UKTAG to develop the second tranche of water quality and water resource standards and conditions, and the results of the stakeholder review of this work can be found at:
http://www.wfduk.org/stakeholder_reviews/stakeholder_review_1-2007/LibraryPublicDocs/UKTAG_Report_Surface_Water_Standards_and_Conditions
Temperature standards for rivers
The proposed temperature standards for rivers are set out in Annex 1.
Ecological impacts
Temperature can affect the growth and development of aquatic species, how they tolerate and metabolise toxic substances, their success in reproduction, in resistance to disease and, ultimately, whether they survive or die. Temperature can also have an indirect effect on aquatic species by causing changes to water chemistry and by altering the solubility and metabolic consumption of oxygen.
Causes of temperature alterations
Temperature can be artificially elevated as a result of the discharge of cooling waters. It can sometimes be artificially lowered by releases of water from behind large dams. Temperature is also affected by climate change. However, this is not expected to cause failures of proposed standards in the short to medium term.
Implications of the proposed standards
More stringent temperature standards currently apply to the majority of rivers in Scotland under the Freshwater Fish Directive, which dates back to 1978. We have an obligation to apply these temperature standards for the purposes of the Freshwater Fish Directive until the repeal of that Directive in 2013. However, in terms of delivering WFD aims and objectives, SEPA will use the proposed new standards for assessing and protecting the ecological status and ecological potential of rivers. Because the proposed standards for "good" are less stringent than the existing standards, compliance with the new standards is not expected to require additional action by operators.
Lochs, transitional and coastal waters
For lochs, transitional waters and coastal waters, UKTAG's advice is that there is currently inadequate scientific understanding to propose new standards representing temperature increases or decreases likely to give rise to significant adverse ecological impacts in these waters. This is in part due to the complex thermal structure of these waters created by natural temperature gradients. Accordingly, we are not proposing to introduce new temperature standards for these waters at this time. The standards established in the Freshwater Fish Waters Directive and the Shellfish Waters Directive will continue to apply to the relevant Protected Areas for fish and shellfish.
Phosphorus standards for freshwater and brackish lochs
The proposed phosphorus standards for freshwater and brackish lochs are set out in Annex 2.
Ecological impacts
Increases in phosphorus concentrations can promote plant growth resulting in changes in composition and biomass of plant communities in the loch. This can then lead to reduced dissolved oxygen levels and lower water transparency. These and related changes can then adversely affect fish populations and invertebrate communities.
Causes of phosphorus enrichment
Phosphorus is contained in sewage effluent discharges, and run-off from land to which fertilisers have been applied. Phosphorus is also released into lochs from fish farms.
Implications of the proposed standards
The proposed standards for "high" and "good" have been derived so as to align with the results of the EU intercalibration exercise on biological standards for plants in lochs.
SEPA's initial estimates indicate that the standard for "good" is failed in approximately 20 % of Scottish freshwater lochs. This represents a small increase (around 5 or 6 additional lochs) compared to the number of lochs failing the management standards previously used by SEPA to control discharges into these waters.
The majority of freshwater lochs in Scotland are naturally nutrient poor ("oligotrophic"). These are also the lochs in which most of Scotland's freshwater aquaculture is based. The proposed standards for oligotrophic lochs are in the majority of cases slightly less stringent than the management standard previously applied by SEPA. In other cases, they are equivalent to the management standards previously applied by SEPA.
Nitrogen standards for transitional and coastal waters
The proposed nitrogen standards for transitional and coastal waters are set out in Annex 3.
Ecological impacts
Increases in nitrogen concentrations can promote plant growth resulting in changes in composition and biomass of plant communities. This can then lead to reduced dissolved oxygen levels, lower water transparency and cause toxic algal blooms. These and related changes can then adversely affect fish and invertebrate communities.
Causes of nitrogen enrichment
Nitrogen is contained in sewage effluent discharges and in run-off from land to which fertilisers have been applied.
Implications of the proposed standards
The proposed standards for "good" in coastal waters and in "clear water" transitional waters are equivalent to the thresholds currently used for the purposes of identifying eutrophication problems as part of the UK obligations under the Oslo and Paris Convention ( OSPAR).
The standards for transitional waters in which light availability is reduced because turbidity ("intermediate", "turbid" and "very turbid" waters) are more relaxed than the OSPAR threshold values. This is because plant growth in these estuaries responds less to nutrients than in clear water estuaries because of the relatively lower light availability.
Initial estimates are that no coastal waters and very few estuaries in Scotland fail the "good" standard.
Suspended solids all surface water bodies
No new standards are proposed for suspended solids in surface water bodies.
Ecological impacts
Suspended solids occur naturally in waters. Some will be the result of natural erosion or exacerbated, for example, by deforestation. In areas of extensive urban development, inputs of suspended solids may be dominated by human impact. However, the range of types of solids, their origins, and their extreme variability in time makes it very difficult to derive standards that can be used helpfully and generally in the classification and management of water bodies. Given the state of current scientific understanding and taking account of the advice of UKTAG, we do not intend to propose numeric standards for suspended solids at this time. Instead, we expect SEPA to consider the need for action based on local evidence of ecological damage or a risk of such damage.
In Protected Areas for freshwater fish, the guideline standard established by the Freshwater Fish Waters Directive will apply in accordance with that Directive.
4.2 CONDITION LIMITS IN RESPECT OF WATER RESOURCES AND MORPHOLOGY IN SURFACE WATERS
This section deals with proposed condition limits for river flow; the proposed condition limits for freshwater flows into estuaries; and the proposed morphological condition limits for lochs, transitional waters and coastal waters.
Details of the technical work undertaken by UKTAG to develop the second tranche of water quality and water resource standards and conditions, and the results of the stakeholder review of this work can be found at:
http://www.wfduk.org/stakeholder_reviews/stakeholder_review_1-2007/LibraryPublicDocs/UKTAG_Report_Surface_Water_Standards_and_Conditions
condition limits for river flows
The proposed condition limits for river flows are set out in Annex 4.
Ecological impacts
The pattern of higher flows in rivers is important in maintaining the processes of sediment erosion, transport and deposition which maintain and refresh river habitats that in turn support biologically diverse river ecosystems. Such flows are also important for triggering and enabling fish migration and other ecological processes.
Causes of impacts on river flows
The condition limits for river flows included in the second tranche are designed to help assess the risks posed by changes to the river flow regime downstream of major dams. There are currently no equivalent limits in Scotland.
Implications of the proposed condition limits
Initial estimates by SEPA suggest that the majority of failures will be caused downstream of major public water supply or hydropower impoundments. These water bodies will typically be designated as heavily modified water bodies. This means that compliance with the condition limits is not required under the WFD if it would have a significant adverse impact on the use for which the water body is designated ( e.g. public water supply). Instead, improvement targets for such heavily modified water bodies will be defined in terms of the practicable mitigation that could be taken to improve the affected river flows. The river flow condition limits would be used to help assess how far downstream of the impoundment the river flows recover to "good", for example, as a result of flow contributions from tributaries downstream of the impoundment and any mitigation that has been implemented.
condition limits for freshwater flows into transitional waters
The proposed condition limits for freshwater flows into transitional waters are set out in Annex 5.
Ecological impacts
Freshwater flows into estuaries maintain the characteristic salinity gradient and low water channel of an estuary which in turn creates different ecological niches in the estuary. The input to the estuary of plant material and other nutrients carried in the freshwater flows is also important to the food web supported by the estuary.
Causes of impacts on freshwater flows into estuaries
The condition limits for freshwater flows into estuaries are designed to help assess the risks posed by major changes to the river flow regime into estuaries, such as those caused by major transfers of water between river catchments or by the regulation of river flows by major reservoirs.
Implications of the proposed condition limits
There are currently no existing condition limits in Scotland for freshwater flow into transitional waters. However, no transitional waters have been identified as being at risk from changes to their freshwater flows and initial estimates by SEPA suggest that no estuaries are currently failing the "good" standard.
Morphological condition limits for freshwater and brackish lochs
The proposed morphological condition limits for freshwater and brackish lochs are set out in Annex 6.
Ecological impacts
The physical structure of lochs and their shore zones provides the diversity of habitats needed by different aquatic plant and animal species at different stages of their lifecycles. The shore zone also provides inputs of plant material and invertebrates which provide a source of food for aquatic animals, such as fish. Engineering works can result in a reduction in the diversity or extent of loch habitats. This can affect the condition of plants and animals which depend on those physical habitats.
Causes of impacts on loch morphological conditions
Engineering works on lochs are much less common than on rivers. Alterations are typically undertaken as part of transport infrastructure works; to enhance water storage for water supply or hydropower schemes; or to facilitate access to the lochs for recreation.
Implications of the proposed condition limits
These new morphological condition limits will provide a standardised and consistent means of assessing risks. As well as ensuring consistency, the use of the condition limits provides efficiencies by reducing the need for detailed site-specific studies and ensures that those studies that are required are properly targeted. This will simplify risk assessments.
The condition limits will also help identify waters affected by the legacy of past morphological alterations. SEPA will use this information to help prioritise restoration efforts.
Morphological condition limits for transitional and coastal waters
The proposed morphological condition limits for transitional and coastal waters are set out in Annex 7.
Ecological impacts
The physical structure of transitional and coastal waters, including their intertidal zones, provides the diversity of habitats used by different aquatic plant and animal species at different stages of their lifecycles.
Causes of impacts on transitional water and coastal water morphological conditions
Engineering works can result in a reduction in the diversity or extent of transitional water and coastal water habitats. For example, extensive intertidal zones can be lost to flood defence works. This can affect the condition of plants and animals which depend on those physical habitats.
Pressures on transitional and coastal waters include navigation activities focused around ports and harbours; coastal defence works to protect land from flooding and erosion; and land claim for waste disposal.
Implications of the proposed condition limits
The morphological condition limits provide a standardised and consistent means of assessing risks. As well as ensuring consistency, the use of the condition limits provides efficiencies by reducing the need for detailed site-specific studies and ensures that those studies that are required are properly targeted.
The condition limits will also help identify waters affected by the legacy of past morphological alterations. SEPA and FRS will use this information to help prioritise restoration efforts.
4.3 Environmental QUALITY standards for specific pollutants in surface waters
The WFD requires Member States to identify and develop standards/ thresholds for specific pollutants which, if exceeded, could result in adverse effects on aquatic ecosystems if discharged to water in 'significant quantities'. UKTAG have identified nineteen such pollutants and these are listed below:
List of specific pollutants
1. 2,4-D
2. Chromium vi
3. Chromium iii
4. Cypermethrin
5. Diazinon
6. Dimethoate
7. Linuron
8. Mecoprop
9. Phenol
10. Toluene
11. Ammonia 5
12. Chlorine
13. Copper
14. Cyanide
15. Permethrin
16. Iron
17. Zinc
18. 2,4-dichlorophenol
19. Arsenic
Further pollutants may be added to the list in future cycles. Pollutants may also be removed from the list if they cease to be discharged in significant quantities.
The proposed standards for specific pollutants in rivers and freshwater lochs and in transitional and coastal waters are set out in Annex 8.
Details of the technical work undertaken by UKTAG to develop these standards and the results of the stakeholder review of this work can be found at:
http://www.wfduk.org/stakeholder_reviews/stakeholder_review_1-2007/LibraryPublicDocs/final_specific_pollutants
Ecological impacts
Specific pollutants are toxic pollutants which can have lethal or sub-lethal effects on aquatic plants and animals if they are above a certain concentration. Where concentrations are at, or lower than, the proposed standards, the quality of the surface water concerned will be able to support an ecological quality of "good" or better than "good".
Implications of the proposed standards
The standards have been derived by UKTAG using a formal technical procedure specified in the WFD. This procedure includes a peer review process.
The standards for ten of the specific pollutants (2-4 dichlorophenol, ammonia in salt water, arsenic, chlorine, copper, cyanide, iron, permethrin, zinc and the annual mean standards for toluene) are the same as the standards which are currently applied ( e.g. under the Dangerous Substances Directive). This means that there are no additional requirements associated with the adoption of these standards.
The ammonia standard in freshwater lochs is the same standard as that for rivers set out in the 2007 Directions. SEPA's initial estimates indicate that there are no failures of this standard.
A detailed analysis of how the other nine specific pollutants compare with existing standards is provided in the UKTAG report. The standards for 2,4 D; chromium VI in salt water; linuron, phenol and mecoprop are significantly more stringent than the existing standards. Available monitoring data in Scotland is limited but initial estimates have not identified failures of these proposed standards .
4.4 surface water Environmental QUALITY standards for priority substances and other dangerous substances in surface waters
'Priority substances and other dangerous substances' are substances identified at European level as posing a significant risk to or via the water environment. The associated environmental quality standards for priority and dangerous substances are also established at European level.
We are required to take account of the standards for priority substances and other dangerous substances in classifying the chemical status of surface water bodies.
Priority substances
Negotiations on a daughter directive, which will set out the environmental quality standards for priority substances, are currently ongoing. However, a common view was reached in June 2007 by the Environment Council of the 27 Member States on environmental quality standards for the priority substances. These standards are based on scientific studies commissioned and coordinated by the European Commission.
The common position of the Environment Council may be subject to change depending on the outcomes of further discussions with the European Parliament expected to be completed in 2008. However, it is unlikely that the standards themselves will change. We therefore believe it is important to include the proposals as they currently stand to provide the full picture.
The standards will help in preparing the first river basin management plans. For completeness and information, we have set out the relevant standards for priority substances in Annex 9.
Other dangerous substances
The 'other dangerous substances', relevant to Scotland's water environment, which are listed in the Dangerous Substances Directive, are also included in Annex 9. The environmental quality standards for these substances already apply to Scotland under that Directive and have been included as they are relevant to river basin management planning process.
4.5 BIOLOGICAL STANDARDS FOR SURFACE WATERS
Role of biological standards
The application of biological standards will play an important role in the river basin management planning process. They will be used alongside the standards and condition limits for water resources, water quality and morphological conditions to help:
- classify the ecological status of our rivers, lochs, transitional waters and coastal waters 6;
- decide where improvements to the water environment are most needed; and
- evaluate the effectiveness of measures taken to protect and improve the ecological health of Scotland's waters.
Although biological standards help in identifying where action is most needed and whether action has been successful, they are not used to determine the level of action required ( e.g. by how much an abstraction or discharge would have to be reduced to enable the achievement of good status). For this, the standards and condition limits for water resources, water quality and morphological conditions are used.
Comparability of standards across Europe
Many of the proposed biological standards have been compared and aligned with the corresponding standards for aquatic plant and animal groups developed by other Member States (See Table 1). This work has been part of a Europe-wide "intercalibration" exercise coordinated by the European Commission. Our proposals include the biological standards that have been agreed through this exercise and which will shortly to be published by the Commission. The use of these intercalibrated standards will help ensure comparability, and hence a level playing field, across Europe.
Table 1: Aquatic plant or animal groups for which the proposed biological standards have been fully or partially intercalibrated (i) ("yes") and those that have not ("no")
Plant or animal group | Transitional waters | Coastal waters | Rivers | Lochs |
|---|
Aquatic angiosperms | Yes | Yes | Standards not applicable (ii) | Standards not applicable (ii) |
Aquatic macroalgae | Yes | Yes | Standards not applicable (ii) | Standards not applicable (ii) |
Phytoplankton - chlorophyll | Yes | Yes | Standards not applicable (ii) | Yes |
Phytobenthos | Standards not applicable (ii) | Standards not applicable (ii) | Yes | No |
Aquatic macrophytes | Standards not applicable (ii) | Standards not applicable (ii) | No | Yes |
Benthic invertebrates | No | Yes | Yes | No |
Fish | No | n/a | Standards not being proposed (iii) | Standards not being proposed (iii) |
Notes to Table 1
(i)Partial intercalibration means that at least one of the indicators used to assess the condition of the plant or animal group has been intercalibrated. For example, in lochs the main indicator, chlorophyll a, has been intercalibrated whereas the indicator of nuisance phytoplankton blooms has not.
(ii)Plant or animal group is not applicable for assessing the ecological status of the water category.
(iii)We are not proposing standards for fish in rivers or freshwater lochs at this time. UKTAG is currently developing standards for fish that will be applicable to fish in Scottish rivers. However, this work is not expected to be complete until 2009/10.
Comparability of the proposed intercalibrated and non-intercalibrated standards
The intercalibration exercise has not yet looked at a number of the biological standards that are required for the purposes of the WFD. A second round of intercalibration is expected to consider these standards before preparations for the first updates of the river basin management plans begin.
This means that a number of the standards we need for river basin management planning have not so far been intercalibrated. Some of these will be used to help assess the impacts of the same pressures as some of the intercalibrated standards (See Table 2).
Comparisons of the non-intercalibrated standards with the corresponding intercalibrated standards have been undertaken by UKTAG. This work indicates that, where there is a corresponding intercalibrated standard, the proposed non-intercalibrated standards are equivalent to, or slightly less stringent, than the intercalibrated standard.
Table 2: Proposed non-intercalibrated standards which initial assessments indicate are of very similar or slightly less sensitivity than a relevant intercalibrated standards
| Rivers | Lochs | Transitional waters |
|---|
Pressure to which standards are sensitive | Standards sensitive to the effects of nutrient enrichment | Standards sensitive to the effects of nutrient enrichment | Standards sensitive to organic enrichment |
|---|
Plant or animal group for which a non-intercalibrated standard sensitive to the pressure is proposed | Macrophyte | Phytobenthos Benthic invertebrates | Benthic invertebrates |
|---|
Plant or animal group for which an intercalibrated standard sensitive to the pressure is proposed | Phytobenthos | Phytoplankton (chlorophyll) | Benthic invertebrates in coastal waters |
|---|
Information on the proposed biological standards
A summary list of the proposed intercalibrated and non-intercalibrated biological standards is set out in:
Further technical details on the different biological standards can be found at: http://www.wfduk.org/UKCLASSPUB/UKCLASSPUB/technical_reports/
4.6 THRESHOLD VALUES FOR GROUNDWATER
The Groundwater Directive 7, a daughter directive of the WFD, requires Member States to establish threshold values for pollutants, groups of pollutants or indicators of pollution contributing to the identification of bodies of groundwater as being at risk of failing to achieve good groundwater chemical status. The threshold values have to be established by 22 December 2008.
The threshold values will be used in assessing the chemical status of groundwater. They do not represent the boundary between good and poor groundwater chemical status. A failure of a threshold value is used as a trigger for investigations aimed at determining whether the conditions for good groundwater chemical status are met. This may involve investigating whether pressures on bodies of groundwater are, or would compromise, the quality of drinking water sources, the quality of surface waters into which groundwater flows or the quality of wetlands connected to the groundwater.
Five separate criteria must be met for a body of groundwater to achieve good groundwater chemical status. These tests are described in detail in the UKTAG recommendations on groundwater classification. The recommendations are available at:
http://www.wfduk.org/stakeholder_reviews/stakeholder_review_1-2007/LibraryPublicDocs/final_gw_sr2007
Different threshold values for different pollutants or indicators of pollution may apply to different tests.
Threshold values have not been proposed in relation to the protection of groundwater dependent terrestrial ecosystems because at present there is insufficient data and understanding to enable appropriate generic threshold values to be derived. Until appropriate information becomes available, UKTAG recommends that site-specific investigations will be required where there are indications that a groundwater terrestrial ecosystem may be at risk because of groundwater pollution.
The threshold values are used for the purpose of assessing the chemical status of groundwater. As well as these values SEPA has to take into account other considerations when dealing with discharges to groundwater, for example, the Groundwater Directive requires Member States to prevent the entry of certain hazardous pollutants into groundwater and limit the entry of others so as to prevent pollution of groundwater. The achievement of this objective will be the principal consideration in the control of discharges.
The proposed threshold values for groundwater are set out in Annex 13 and have been derived by SEPA using the methodology 8 recommended by UKTAG. The methodology has been subject to a stakeholder review co-ordinated by UKTAG.
Implications of the proposed threshold values
The threshold values are used to trigger investigations aimed at determining whether the criteria for good groundwater chemical status are met or not. Consequently, they drive investigative action rather than environmental improvements.
The threshold values proposed have been set at levels corresponding to other established risk-criteria. These include:
- surface water environmental standards for the tests relating to the impact of groundwater pollution on surface waters; and
- drinking water standards for the impact of groundwater pollution on drinking water sources.
Consequently, the threshold values are only expected to trigger investigations which are proportionate to the environmental risks involved.
4.7 Proposals for updating the 2007 Directions
In the main, the 2007 Directions set out environmental standards and condition limits consistent with "high" and "good" ecological quality. Annexes 14, 15 and 16 below set out proposals for updating the 2007 Directions to include standards and condition limits consistent with "moderate" and "poor" ecological quality.
The extended standards will help SEPA prioritise action to improve the water environment by helping to assess the relative severity of adverse impacts. It will also help with the determination of the likely causes of ecological impacts where biological standards are found to be failed.
We are also proposing amendments to the morphological condition limits for rivers. The amendments, which are set out in Annex 16, bring the conditions limits into line with the latest advice from UKTAG and correct minor technical drafting errors in their original Report.
Implications of the proposed updates
The principal objective of the WFD is to restore water bodies to good ecological status. The proposed standards for moderate and poor will help assess how far away we are from this objective.
They will also help SEPA make judgements about the capacity of the environment to accommodate proposals for abstractions, discharges and engineering works before there is a significant risk of deterioration of status. We believe this will facilitate the sustainable use of the water environment and ensure a consistent approach to assessing environmental risks.
« Previous | Contents | Next »