International water law is generally applied to disputes between states concerning surface bodies of water crossing international borders. Disputes and policy-making over transboundary ground water resources, however, have traditionally been determined on an ad hoc basis or based on regional custom. This disparate treatment stems primarily from the misunderstood nature of ground water and its relationship to surface water among government officials, policy-makers, jurists, and others. The result often has been the degradation of subsurface waters on both sides of political boundaries, and unwittingly, of numerous international surface bodies of water.
International concern over regional and global availability and quality of fresh water resources has recently generated reexamination of water use and allocation. As a consequence, there is now a growing belief that international water law should be applied to surface as well as subsurface water resources equally. This trend has been encouraged, in no small part, by the growing understanding of the indissociable relationship between surface and ground water resources.
In the recent World Court decision in the Case Concerning the Gabcikovo-Nagymaros Project (Hungary v. Slovakia), the International Court of Justice considered, among other claims, allegations of transboundary environmental harm to both surface and ground water resources stemming from the construction and operation of the Gabcikovo Dam and Danube River diversion channel. While the Court addressed the two states' conduct and relations during the dispute, it gave only cursory mention to the environmental concerns presented. Specifically, the Court did not fully consider the consequences to the region's ground water resources or the applicable law, but rather reached its conclusion based solely on state obligations as defined by treaty and international law. In so doing, the Court artfully skirted the sophisticated but vexing issues of potential environmental harm and applicable laws, including the implication of international water law to subsurface water resources. Notwithstanding the decision, the facts of the case provide an interesting scenario on which to consider both the relationship between transboundary surface and ground water resources, as well as the applicable international law.
Gambling with Groundwater: Physical, Chemical, and Biological Aspects of Aquifer-Stream Relationship
Gabriel Eckstein & Yoram Eckstein,
International Water Law, Groundwater Resources and the Danube Dam Case,
Available at: https://scholarship.law.tamu.edu/facscholar/892