State responsibility in international law for transboundary water-related harm: The emergence of a new ecosystems-based paradigm?

Though one might reasonably expect that transboundary harm caused to the riparian interests of watercourse States should quite easily give rise to findings of legal responsibility on the part of the State causing such harm, this has rarely been the case. One reason commonly advanced is that the primary rules of international water law, breach of which would give rise to State responsibility, are vague and uncertain as regards their precise normative implications. However, recent developments regarding the requirement to protect riverine ecosystems and to maintain related ecosystem services provide an important degree of clarity as regards the standard of conduct expected of watercourse States, and the types of harm which may be compensable. This is welcome considering the important role that State responsibility might be presumed to play in giving effect to the values and commitments enshrined in the rules and principles of international water law.