The mainland of Portugal has an area of 88,700 km2 and 9.4 million inhabitants. It is bounded to north and east by Spain and to west and south by the Atlantic Ocean. The five largest rivers the Douro, the Tejo, the Guadiana, the Sado and the Mondego, which all have a Portuguese catchment area greater than 5,000 km2, cover around three quarters of the Portuguese territory. Portugal has only few natural lakes, but nearly all the large rivers have several reservoirs, about 140 in all. Portugal has a long coastline along the Atlantic Ocean and some important estuarine areas.

Inland surface waters

Surface water quality monitoring is carried out by the Regional Directorates of Environment and Natural Resources (DRARN) within the geographical area of their authorities. Each DRARN has a surface water monitoring programme. A nation-wide water quality network (R1) has been established and is coordinated by the National Institute of Water (INAG). The national network is composed of the five regional monitoring networks (Norte, Centro, Lisboa e Vale do Tejo, Alentejo and Algarve). The national network consists of 109 sampling sites, primarily in large rivers (24 river systems). The most important reservoirs whose main use is domestic water supply are included in the R1 programme as well.


The objectives of the monitoring programme are to assess the environmental state and trends of surface waters, to provide information to determine whether regional and national objectives and international legislation are complied with.

Sampling and variables measured

Sampling and analyses are undertaken by DRARN. Water samples are taken at monthly intervals and analyzed for general chemical and physical variables, organic pollution indicators, nutrients and some heavy metals. Harmonization and standardization of analytical methods has been carried out by INAG.

Data storage

The data are stored at regional level and sent to INAG with the aim of compilation and publishing.

Transboundary rivers

The most important Portuguese rivers are shared with Spain and the two countries are currently trying to reach an agreement on river monitoring. Automatic sampling stations with teletransmission and early alarm systems are planned to be installed. Since 1993 the National Institute of Water (INAG) has had the overall responsibility of management of transboundary rivers. The DRARNs have executive function and operational responsibilities in the geographical region within their authorities.

Table 3.12: National surface water monitoring programmes in Portugal

No. Name Responsible institution Variables Period of operation & Sampling Frequency (SF) Geographical coverage Data & national reporting
Rivers and streams
R1 Water Quality Network
Rede de qualidade da água
INAG & DRARN Chemical and physical variables Since
SF: monthly
Nation-wide, 109 sampling sites in primarily large rivers Database: DRARN
Reporting: INAG

INAG: National Institute of Water; DRARN: Regional Directorate of Environment and Natural Resources

Marine waters

Monitoring of Portuguese marine waters is undertaken in a number of programmes covering coastal areas, estuaries and bathing waters. Only sparse information about the marine programmes has been received.


Geographic coverage


Filed under:
Filed under: surface water
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