Priority hazardous substances
Priority hazardous substances, which are now subject to specific regulation pursuant to Article 16 of the WFD, have been regulated by the EU since the 1970s. A directive on pollution caused by certain dangerous substances discharged into the aquatic environment, which identified groups of dangerous substances, was adopted in 1976.39 In the 1980s it was supplemented by so-called daughter directives setting limit values and quality objectives for discharges of certain dangerous substances, including mercury and DDT.     In 2006 the 1976 Directive was codified as Directive 2006/ 11/EC.41 However, the framework for control of pollution by dangerous substances has been gradually replaced by the WFD and Directive 2006/11/EC was repealed in 2013, when the relevant provisions of the WFD were to have been fully implemented.42
As early as 2001, a first list of priority substances according to the WFD was adopted and added to the WFD as Annex X.43 However, in 2008 a new Directive 2008/105/EC on environmental quality standards in the field of water policy was adopted (the ‘Priority Substances Directive’). 44 It lays down EQS for forty-five priority substances (ie substances that have been prioritised for action at EU level) and other pollutants as provided for in Article 16 of the WFD, with the aim of achieving good surface water chemical status in accordance with Article 4 of that Directive. Among the substances for which EQS are set out are DDT, dioxins, mercury, lead, and benzene. The list of priority substances shall be updated regularly. For these pollutants, measures shall be taken aimed at their progressive reduction.
Within two years of the inclusion of a substance on the list of priority substances the Commission shall submit proposals, at least for emission controls for point sources and EQS. In the absence of agreement at EU level, Member States must take such action five years after the date of inclusion in the list. (WFD, Art 16.)
Some of the priority substances have been identified as priority hazardous substances for which Member States should implement necessary measures with the aim of the cessation or phasing out of discharges, emissions, and losses.
Amendments decided in 2013 introduced an obligation on the Commission to establish a watch list of substances for which EU-wide monitoring data are to be gathered for the purpose of supporting future prioritisation exercises.45 A first watch list was established in 2015 and is to be updated every two years.   
The list of priority substances previously set out in Annex X to the WFD has been repealed and replaced by Annex II to Directive 2008/105/EC. The Directive also repeals the old ‘daughter directives’ from the 1980s.
-  Council Directive 84/ 156/EEC on limit values and quality objectives for mercury discharges bysectors other than the chlor-alkali electrolysis industry  OJ L 74/49; Council Directive 86/280/EEC on limit values and quality objectives for discharges of certain dangerous substances included inList I of the Annex to Directive 76/464/EEC  OJ L 181/16.
-   OJ L 64/52. 42 Directive 2000/60/EC, Art 22.
-  43 Decision No 2455/2001/EC of the European Parliament and of the Council establishing the list of
-  priority substances in the field of water policy and amending Directive 2000/60/EC  OJ L 331/1.
-   OJ L 348/84.
-  On the 2013 amendments, including the watch list, see K Kern ‘New Standards for the ChemicalQuality of Water in Europe under the new Directive 2013/39/EU’ (2014) 11 Journal for EuropeanEnvironmental & Planning Law 31—48.
-  46 Commission Implementing Decision (EU) 2015/495 establishing a watch list of substances forUnion-wide monitoring in the field ofwater policy pursuant to Directive 2008/ 105/EC of the EuropeanParliament and of the Council (notified under document C(2015) 1756)  OJ L 78/40.
-   OJ L 135/40.
-  48 On the extent of the obligation to collect urban waste water see Case C-395/13 Commission v Belgium ECLI:EU:C:2014:2347.