Decree-Law No. 236/98 establishing quality standards, criteria and objectives in order to protect the aquatic environment and improve the quality of water according to its main uses.

This Decree-Law establishes water quality standards in order to protect, preserve and improve water resources and their different uses. It consists of 8 Chapters and 22 Annexes defining different types and uses of waters and establishing responsibilities and composition of competent authorities entitled to manage and carry out control on this sector. It specifies water quality standards for human consumption, water treatment, aquaculture purposes, abstraction, waste water uses, waterworks, equipment, recreational water, irrigation, etc. Annexes concern freshwater quality standards for human consumption and aquaculture purposes (including brackish water), methods of analysis, substances contained in waters, water supply for irrigation purposes, maximun residue limit of pesticides, etc.