CONTENTS 1 INTRODUCTION 1 1.1 BACKGROUND 1 1.2 SCOPE 5 2 COUNTRY REPORT - PORTUGAL 7 2.1 PORTUGAL - THE CONTEXT 7 2.2 THE DESIGNATION PROCESS - THE URBAN WASTE WATER TREATMENT DIRECTIVE 9 2.3 THE DESIGNATION PROCESS - THE NITRATES DIRECTIVE 20 3 MARINE/COASTAL WATER AND ESTUARIES 23 3.1 INTRODUCTION 23 3.2 EUTROPHICATION - OVERVIEW 23 3.3 THE NORTH COAST - VULNERABILITY 25 3.4 THE TAGUS ESTUARY 26 3.5 THE SADO ESTUARY 29 3.6 THE MONDEGO ESTUARY 33 4 REVIEW OF FRESHWATERS DESIGNATED AS SENSITIVE AREAS UNDER THE URBAN WASTE WATER TREATMENT DIRECTIVE 36 4.1 SURFACE FRESHWATER 36 4.2 THE PORTUGUESE CLASSIFICATION SYSTEM 36 4.3 SURFACE FRESHWATER QUALITY - AN OVERVIEW 37 4.4 NITRATE CONTAMINATION 41 4.5 WATERS USED FOR THE ABSTRACTION OF DRINKING WATER 48 4.6 GROUNDWATERS 54 5 REVIEW OF THE WATERS DESIGNATED AS VULNERABLE ZONES UNDER THE NITRATES DIRECTIVE 57 5.1 INTRODUCTION 57 5.2 SURFACE FRESHWATER 57 5.3 GROUNDWATERS 60 6 CONCLUSIONS 78 7 REFERENCES 80 ANNEX ANITRATE CONCENTRATIONS IN GROUNDWATER ANNEX BSURFACE FRESHWATER QUALITY MAPS ANNEX CNITRATE CONCENTRATIONS IN SURFACE FRESHWATER ANNEX DMAPS 1 INTRODUCTION 1.1 BACKGROUND The objectives of the Urban Waste Water Treatment Directive (UWWTD)1 and the Nitrates Directive2 are to reduce and prevent “pollution”, from urban waste water treatment plants and from agricultural nitrates respectively. Some aspects of the Directives are closely defined, others are – to some degree – left open to interpretation by Member States, individually or collectively. The waters that must be studied and identified under both the Urban Waste Water Treatment Directive (91/271/EEC) and the Nitrates Directive (91/676/EEC) are similar. Consequently, the examination of the identification of these waters has taken place concurrently during this study. 1.1.1 Nitrates Directive The Nitrates Directive deals explicitly and exclusively with pollution resulting from agricultural activities. The Directive defines pollution as direct or indirect discharges of “nitrogen compounds from an agricultural source into the aquatic environment” which, (among possibilities irrelevant to estuarine and coastal waters) causes “harm to living resources and to aquatic ecosystems.” The definition of eutrophication is identical to that of the UWWTD except that it is restricted to nitrogen compounds from agriculture. The Directive has a similar dual objective – the reduction of water “pollution caused or induced by nitrates from agricultural sources”, and “preventing further such pollution”. Article 3.1 requires the identification of polluted waters, and those which “could” be affected if action is not taken, according to the criteria set out in Annex I. This Annex simply states that “Waters referred to in Article 3 (1) shall be identified making use, inter alia, of the following criteria.” Three criteria are set out: 1. Whether surface freshwaters, in particular those used for the abstraction of drinking water, contain or could contain, if action pursuant to Article 5 is not taken, more than the concentration of nitrate laid down in accordance with Directive 75/440/EEC; 2. Whether groundwaters contain more than 50 mg/l nitrate or could contain more than 50 mg/l nitrate if action pursuant to Article 5 is not taken; 3. Whether natural freshwater lakes, other freshwater bodies, estuaries, coastal waters and marine waters are to be eutrophic or in the near future may become eutrophic if action pursuant to Article 5 is not taken. 1Council Directive of 21 May 1991 concerning urban waste water treatment (91/271/EEC). 2 Council Directive of 12 December 1991 concerning the protection of waters against pollution caused by nitrates from agricultural sources (91/6765/EEC) ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 1 1.1.2 Urban Waste Water Treatment Directive There are a number objectives and requirements of the UWWTD that relate to the estuarine and coastal environment. The main elements are: • First, the stated objective, “to protect the environment from the adverse effects” of waste water discharges and “pollution” arising from waste water (Article 1); • In order to achieve this secondary treatment shall generally be required (Article 4); • However within ‘Sensitive Areas’ additional action is required, throughout the catchment area, for those treatment plants that contribute to “pollution” (Article 5.5). For estuaries and coastal waters the current or future potential for eutrophication is a criteria that results in their prescription as a Sensitive Area (Annex II). While Annex II allows some flexibility for “small agglomerations”, the requirement for “large agglomerations” is absolute: phosphorus and/or nitrogen should be removed unless it can be demonstrated that removal will have “no effect” on the “level” of eutrophication – a claim that a contribution will be ‘insignificant’ does not provide a defence for failure to implement. • In addition an estuarine or coastal water “must be identified” as a Sensitive Area where further treatment than that set out in the UWWT Directive is “necessary to fulfil [other] Council Directives”. • The Directive also allows for the creation of ‘Less Sensitive Areas’, LSAs, providing “comprehensive studies” demonstrate that discharges “will not adversely affect the environment” (Article 6.2). Such discharges must receive at least primary treatment. In estuaries this stipulation applies to discharges from “agglomerations” of between 2,000 and a maximum of 10,000 person equivalents, p.e.. Above this size LSA status is not allowed and the provisions of Article 4 regarding secondary treatment apply. In coastal waters the equivalent limit is 150,000 p.e. • Estuarine discharges under 2,000 in estuaries or under 10,000 p.e. in coastal waters must, by 2005, receive “appropriate” treatment – that necessary to meet the “relevant” aspects of this and other Directives. • Other Directives relevant to estuaries and coastal waters included those relating to hazardous substances, bathing water, shellfish, and habitats and species protection. Article 5: For the purposes of paragraph 2 in the Directive, Member States shall by 31 December 1993 identify sensitive areas according to criteria laid down in Annex II. ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 2 Criteria for identification of sensitive and less sensitive areas (a) Sensitive areas A water body must be identified as a sensitive area if it falls into one of the following groups: • natural freshwater lakes, other freshwater bodies, estuaries and coastal waters which are found to be eutrophic or which in the near future may become eutrophic if protective action is not taken. The following elements might be taken into account when considering which nutrient should be reduced by further treatment: • lakes and streams reaching lakes/reservoirs/closed bays which are found to have a poor water exchange, whereby accumulation may take place. In these areas, the removal of phosphorus should be included unless it can be demonstrated that the removal will have no effect on the level of eutrophication. Where discharges from large agglomerations are made, the removal of nitrogen may also be considered; • estuaries, bays and other coastal waters which are found to have a poor water exchange, or which receive large quantities of nutrients. Discharges from small agglomerations are usually of minor importance in those areas, but for large agglomerations, the removal of phosphorus and/or nitrogen should be included unless it can be demonstrated that the removal will have no effect on the level of eutrophication; • surface freshwaters intended for the abstraction of drinking water which could contain more than the concentration of nitrate laid down under the relevant provisions of Council Directive 75/440/EEC of 16 June 1975 concerning the quality required of surface water intended for the abstraction of drinking water in the Member States if action is not taken; Areas where further treatment than that prescribed in Article 4 of this Directive is necessary to fulfil Council Directives. (b) Less sensitive areas A marine water body or area can be identified as a less sensitive area if the discharge of waste water does not adversely affect the environment as a result of morphology, hydrology or specific hydraulic conditions which exist in that area. When identifying less sensitive areas, Member States shall take into account the risk that the discharged load may be transferred to adjacent areas where it can cause detrimental environmental effects. Member States shall recognize the presence of sensitive areas outside their national jurisdiction. ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 3 The following elements shall be taken into consideration when identifying less sensitive areas: open bays, estuaries and other coastal waters with a good water exchange and not subject to eutrophication or oxygen depletion or which are considered unlikely to become eutrophic or develop oxygen depletion due to the discharge of urban waste water. UWWTD: Biochemical oxygen demand and eutrophication Having allowed for the requirements of other Directives, two aspects of pollution specifically deal with by the UWWTD are the biochemical oxygen demand (BOD) of the decomposing sewage effluent, and eutrophication. BOD, with quantitative criteria set out in the Directive’s annex, is relatively straight-forward, at least in its definition. However that for eutrophication is more complex. The Directive states (2.11) that “‘eutrophication’ means the