When Directive 2004/35/EC on environmental liability with regard to the prevention and remedying of environmental damage (the environmental liability directive, or ‘ELD’) was adopted in 2004,97 it was a compromise that resulted from lengthy negotiations. The Commission’s initial proposal included, among other things, a secondary obligation for Member States to take necessary preventive measures in cases where there is an imminent threat of environmental damaged However, that was seen as contrary to the principle that the polluter should pay and before the Directive was adopted it was replaced with an authorisation—rather than an obligation—for national authorities to take preventive action when the operator fails to do so.
The elaboration of the ELD was prompted by the many contaminated sites in the EU, with associated health risks, and by the loss of biodiversity throughout the Union. The prevention and remedying of environmental damage is to be implemented through the furtherance of the polluter-pays principled The core of the ELD is the principle that an operator whose activity has caused environmental damage or the imminent threat of such damage is to be held financially liable. Operators shall thereby be induced to adopt measures and develop practices to minimise the risks of environmental damage so that their exposure to financial liabilities is reduced.100
Unsurprisingly, liability is not seen as a suitable instrument for dealing with pollution of a widespread, diffuse character, where it is impossible to link the negative environmental effects with acts or failure to act of certain individual actors.101 However, as will be discussed presently, it can be permissible to rely on presumptions in order to establish a causal link between an operator and certain environmental damage, thereby making it easier to pinpoint a responsible operator.
In line with this, the ELD aims to establish a framework of environmental liability based on the polluter-pays principle, to prevent and remedy environmental damage (Art 1). 
-  6 Report from the Commission on progress in implementing Regulation (EC) 166/2006 concerning the establishment of a European Pollutant Release and Transfer Register (E-PRTR) (5 March 2013) COM(2013) 111 final. 97  OJ L 143/56. 98 See Art 4 of Proposal for a Directive of the European Parliament and of the Council on environmental liability with regard to the prevention and remedying of environmental damage, COM(2002)17 final. 99 On this principle, see section 2.4.8. i°° Preambular paras 1 and 2. ioi Preambular para 13.