A Gulf Between Law and Practice? Marine Environment Protection and Desalination Discharges in the Persian Gulf

The countries bordering the Persian Gulf (also known as the Arabian Gulf) are among the most water-scarce in the world. This has led them to rely heavily on seawater desalination to meet their freshwater needs. However, while desalination is vital for human life in the Gulf region, it produces a toxic by-product: desalination brine. This brine is not ‘salty water’; it contains treatment chemicals and is denser than seawater, causing it to sink and spread along the seabed, harming marine life in its path. Local environmental effects include the die-off of corals and seagrasses near outfalls, as well as fish deaths and migrations.

Experts caution that large-scale brine discharges may alter the Gulf’s salinity and temperature, though basin-wide effects remain uncertain. While some modelling suggests average salinity could remain within natural limits, this offers limited reassurance. In shallow coastal areas, where brine and heat concentrate, local conditions may already be approaching ecological thresholds. With desalination volumes projected to rise significantly, the cumulative impacts remain poorly understood, which complicates efforts to both assess and protect against the environmental risks associated with desalination.

This post examines how international law and regional legal frameworks address the potential harms associated with desalination. Based on this, it argues that the absence of enforcement and cooperation has allowed desalination to proceed without the precaution needed to protect the environmental conditions on which long-term human habitation in the region depends.

International Law and Brine Discharges in the Gulf

The United Nations Convention on the Law of the Sea (UNCLOS) is highly relevant to the issue of desalination brine in the Gulf. Except for Iran and the UAE, all Gulf countries are parties to UNCLOS, which imposes an obligation on States to ‘protect and preserve the marine environment’ (Article 192) and to take measures to prevent, reduce and control pollution of the seas from any source (Article 194). This includes pollution from land-based sources such as industrial discharges and runoff (Article 207), which would cover brine outflows from coastal desalination plants (see also ITLOS’ Advisory Opinion on Climate Change, paras 267–273). States must adopt laws and standards to minimise such pollution and enforce them effectively within their jurisdiction (Articles 207 and 213).

In practice, these obligations mean that States are expected to regulate desalination projects (through permitting, standards, etc.) to ensure they do not cause significant harm to the marine environment. The duty to act with ‘due diligence’ in preventing transboundary harm is a well-established principle in international law (Article 206; Pulp Mills, para 101). The precautionary approach informs the scope of the due diligence obligation under UNCLOS. As confirmed by the ICJ in Pulp Mills (para 204), environmental impact assessments are required where there is a risk of significant harm, irrespective of complete scientific certainty (see also the ICJ advisory opinion on the Obligations of States in Respect of Climate Change, para 293–294). The South China Sea Arbitration (paras 984–993) reinforced this by affirming that, in accordance with UNCLOS Article 206, States must assess potential impacts where harm is plausible, not proven, and communicate the results of such assessments.

Of particular relevance to the management of the Gulf is Part IX of UNCLOS concerning ‘Enclosed or Semi-Enclosed Seas’. The Persian Gulf, bordered by eight states and connected to the Indian Ocean by the narrow Strait of Hormuz, squarely fits the definition of a semi-enclosed sea in Article 122 (see also Gioia). Article 123 of UNCLOS provides that countries bordering such a sea ‘should cooperate’ in the exercise of their rights and in performing their duties under the Convention, and ‘shall endeavor to coordinate’ their actions concerning the management, conservation, exploitation of marine resources, the protection of the marine environment, and research. While Article 123 is phrased in permissive terms (‘should cooperate’), the article does carry weight in relation to States’ duty to cooperate (see Zhang).

The cooperative spirit of UNCLOS Part IX is reinforced by the binding duty to cooperate in Article 197, which requires states to coordinate ‘as appropriate’ regionally on marine environmental protection. Taken together, these provisions require that no Gulf nation should address the desalination brine issue in isolation; international law envisages mutual assistance and aligned efforts. This could involve notifying and consulting neighbours about new desalination plants, standardising discharge limits to ensure uniform environmental safeguards, or establishing joint contingency plans in the event of a pollution incident.

Regional Marine Environment Cooperation in the Gulf

In 1978, all eight Gulf littoral States adopted the Kuwait Regional Convention for the Protection of the Marine Environment (Kuwait Convention). With its accompanying Action Plan, the Convention established a legal and institutional framework for environmental collaboration in the Persian Gulf and Gulf of Oman in what is now known as the Regional Organization for the Protection of the Marine Environment (ROPME) Sea Area.

The Kuwait Convention imposes broad obligations similar to UNCLOS: States must ‘individually and/or jointly take all appropriate measures […] to prevent, abate and combat pollution of the marine environment in the Sea Area’ (Article III) and specifically address different categories of pollution through subsequent protocols. Crucially, Article VI commits states to control pollution from land-based sources, requiring them to prevent and reduce pollution caused by ‘discharges from land reaching the Sea Area […] including outfalls’. This language thus squarely encompasses desalination plants releasing brine into the Gulf.

Building on the Kuwait Convention, the Gulf states negotiated several detailed protocols, including the 1990 Protocol for the Protection of the Marine Environment Against Pollution from Land-Based Sources. The Protocol provides a more concrete roadmap for tackling coastal and industrial pollution. Notably, the Protocol’s Annex III lists priority effluents for which regional regulations and standards must be developed and explicitly includes discharges from desalination facilities. However, although the protocol went into effect in 1993 and ROPME itself has acknowledged the need to implement it, no progress has seemingly been made in establishing a regional framework regulating desalination discharges (it should be noted that the most recent ROPME report concerning the marine environment was published in 2013).

Outside of the ROPME context, the Gulf Cooperation Council has floated initiatives for collective resource management, such as the Unified Water Strategy and discussions of linking desalination networks. These plans, however, have seen limited progress. Thus, in practice, the regional approach has proven ineffective in the Gulf region. While ROPME has facilitated some progress, the task of regulating the environmental impacts of desalination, particularly brine discharges, has fallen to national authorities in the absence of binding regional standards.

In the Gulf, Fragmentation Comes at the Expense of Precaution

National authorities have instead filled this regulatory vacuum by introducing their own discharge limits and permitting schemes. Similarly, all Gulf countries today have domestic EIA regulations in place that seek to manage the environmental impact of desalination, and countries typically require that an EIA be conducted before building any new desalination plant. Gulf countries have sought to minimise harm by deploying offshore multi-point diffusers to spread brine over a wider area. Where currents are weak, multiple brine discharge points are used to avoid saline buildup. Bahrain and Qatar, for example, have also explored alternative strategies such as blending brine with power-plant cooling water to reduce salinity and temperature before discharge.

There is a clear trend of integrating stricter environmental standards into new projects. But a challenge remains in harmonising these efforts and keeping pace with the scale-up of desalination capacity. The result is a fragmented regulatory landscape in which Gulf states act independently, without common discharge benchmarks or harmonised monitoring protocols. This undermines the cooperative logic of both UNCLOS and the Kuwait Convention, as well as the operational purpose of its Protocols. ROPME continues to facilitate low-intensity dialogue, ‘research cruises’, and periodic assessments; however, the persistent failure to develop regional desalination standards, despite clear treaty obligations, remains a notable gap in the region’s marine environmental governance.

The absence of a coherent regional framework has allowed desalination to expand broadly on the terms of national utility planners, rather than through coordinated ecological stewardship. While individual Gulf states have adopted mitigation technologies and EIA, these remain reactive and unaligned, with limited transparency and weak accountability mechanisms. The cumulative ecological effects of brine discharge – with more than 800 desalination plants in the Gulf – especially in shallow zones with limited circulation, cannot be adequately addressed through piecemeal regulation. Without agreed-upon regional thresholds and binding rules governing permissible discharge practices, desalination may significantly contribute to the degradation of the Gulf’s marine environment.

Conclusion

The ‘brine problem’ in the Persian Gulf is a textbook example of a shared environmental issue that requires collective governance. As the ICJ recently affirmed in its advisory opinion on the Obligations of States in Respect of Climate Change, the human right to a clean, healthy and sustainable environment is essential for the enjoyment of other rights, including access to water (para 393). In the Gulf, this creates a regulatory tension: desalination provides potable water and thereby fulfils a core human right, yet it does so through brine discharges that may degrade the marine environment, thus potentially undermining the very ecological conditions on which that right ultimately depends.

Ultimately, safeguarding the Gulf’s marine ecosystems amid growing desalination deployment will require stronger cooperation and a commitment to ensure that precaution is taken to prevent development at the cost of ecological degradation.