The ENVIBASE-Project

Documentation / Online Handbook

Water

Description of the Problem

In the greater Athens area, there is a single water authority which is responsible for water and wastewater management for over 3 million people. Up until 1980, water management in the greater area was carried out by the Greek Water Company, and wastewater management was the responsibility of the so-called Wastewater Organisation of the Capital. In 1980, the government issued specific legislation for reforming the water and sewage management sector in Greece.

According to the provisions of the above-mentioned legislation (law 1068), in the greater area of Athens, the body responsible for water and sewage management is a legal entity of private law but of public purpose, supervised by the Ministry for the Environment, called Athens Water Supply and Sewage Company, abbreviated in Greek as EYDAP.

The bodies of water from which water, which is to be supplied to the greater Athens area, is extracted are situated at fairly long distances. The following are being used today :

• The Marathon Reservoir, initially constructed in 1925 and expanded later by damming Assopos river at the place of the ancient lake of Marathon, approximately 42 km away from the centre of Athens.
• The Yliki Lake, connected to Athens by a closed gravity aqueduct; 143 km long, constructed in 1957.
• The Mornos River Reservoir, which involved the construction of an earth dam 150 km northwest of Athens. The Mornos Reservoir will be further expanded thanks to water transferred from the Evinos river dam, currently under construction.

Serious water shortage problems due to low rainfall occurred between 1992-94. Special measures taken by EYDAP, such as price increases, penalties for excessive consumption, and awareness campaigns proved quite effective in controlling consumption.

There are four water purification plants, approximately seventy pumping stations, and the estimated length of the distribution network is 7,000 km. The latter has been constructed in many stages, and without a master plan, and is in some cases very old and in urgent need of replacement. The mains in some cases belonged to private bodies and in other case to municipalities, and they have been poorly maintained. Leakages are estimated to exceed 20 % on average, but there is currently a great effort to diminish them. In other cases, the mains still belong to the municipalities, which are usually not very prompt in paying their debts to EYDAP. The sewer system construction began in 1858 in the greater Athens area. Nowadays, municipalities construct the secondary drains and EYDAP constructs main sewers of the separate sewage. The total length of the network is 6,500 km and the number of pumping stations is forty-one. Wastewater treatment takes place in two plants, namely Psyttalia and Metamorfossis.

The Metamorfossis plant was inaugurated in 1986. It is a rather small plant, treating 8,000 m³/day of septic tank waste and 13,000 m³/day of sewage. Septage is delivered to the plant by trucks and their organic load is approximately four times that of sewage.

The Psyttalia plant is situated on an island at a distance of 1.5 km from the coast. At present, there is only primary sedimentation treatment, but the biological stage is under construction. 750,000 m³/d of wastewater is treated there, decreasing the organic load (BOD) by 38 % and the SS by 43 %. The Psyttalia plant has substantially contributed to the revitalisation of the Saronicos Gulf, and further improvement is expected after the secondary treatment is finished.

The construction--still in progress--and operation of the Psyttalia WWT plant, designed to treat almost the whole of the municipal wastewater of the metropolitan area, will decisively solve the serious sewage disposal problem in Athens. For the time being, the municipal wastewater reaching the Psyttalia plant undergoes a typical pre-treatment, followed by a primary sedimentation, before being discharged into the sea. The envisaged incorporation of a secondary treatment plant, including nutrient removal, to the existing installations will eventually help, in a few years time, the Saronicos Gulf area to become healthy once again. The commissioning of the new biological plant is expected by 1998.

The considerably positive results from the operation of the Metamorfossis WWT plant encouraged the administration of many local authorities of certain small towns and/or tourist villages to start constructing their own treatment plants. Furthermore, the contribution of the EC funds resulted in a full promotion of the infrastructure in the field of environmental protection.

In addition, public awareness of and sensitivity to the need for better living conditions and governmental policy for wastewater treatment in any municipality throughout the continental and island territory of Greece mobilised a national effort to eliminate the sources of water pollution. EC Directive 91/271 is now a milestone and an official guide for the future environmental trends in all EC countries.

Summarising the institutional arrangements in the water sector in Attica, the following statements can be made:

• The Ministry of Environment Physical Planning and Public Works is responsible for the policy making.
• The Athens Water Supply and Sewage Company (EYDAP) is responsible for water and wastewater services and is supervised by the Ministry of Environment Physical Planning and Public Works.

The National law 1650/86 is the main legal framework for the protection of the environment. Law 1739/87 established the institutional framework for the management of water resources. The Common Ministerial Decisions A5/2280/83 and A5/5180/88 refer to the protection of water resources that are used for water supply in the Athens area. In accordance with relevant EU directives, the Common Ministerial Decision 46399/1352/86, concerning the quality of surface waters for: water supply, swimming, and the survival of fish, was issued, defining measurement methods, sample frequency, and drinking water analysis. A series of decrees was also established for the protection of water quality. The Common Ministerial Decision 5673/400/97 defines the measures and terms for the management of wastewater treatment.

Data Sources

Databases and maps concerning water resources and their uses in Greece are not widely used so far. The main reason for this is the fact that there are various bodies responsible for planning, exploitation, and control of water and, there is therefore no centralised procedure for data collection on a permanent basis.

The most interesting study carried out for Athens which concerns the ENVIBASE project is described below.

In 1994, for the first time in Greece, a team of experts on water issues developed a complete system for water resources management concerning the region of Attica. Based on this system, the water balance of Attica can be precisely defined and all the necessary actions/measures/technical works can be planned, in order to ensure the rational exploitation of the surface and underground water resources and also the armouring of Attica against floods.

Very important quantitative and qualitative results and proposals can be drawn from the use of the above-mentioned system. The system shows the areas of Attica with the best zones for exploitation of underground waters in order to construct productive hydro-drilling plants. It also shows the areas sensitive to catastrophic floods. Additionally, the system demonstrates the irrigating water supply of the local authorities according to their needs. This study was carried out basically for the purpose of flood prevention. The data it contains refers only to a certain time period and no monitoring and updating has since been undertaken.

Methods

Measurement values were only given for some maps in full like in the case of existing wells for example. For other cases such as iso-piezometric maps, hydrographic mathematical models were employed and iso contouring, interpolation and gridding also became useful.

Results

The results of this study are not available to the public. They belong to the Attica Region and serve mainly as a guideline for the anti-flooding strategy the region has to draw up. However, in some cases, municipalities consult these maps in order to plan water drilling and forecast future surface water discharges.

It seems urgent that a single agency is created in Greece for the long-term planning of water resources, in which case the results of such studies as the one described here will become indispensable.

Uses

The main use of the aforementioned system is for consultancy purposes for all the relevant agencies and bodies.

Addresses for Responsible Agencies