A. Equity in Theory: How to Define and Assess the ERU?

Equity is situated at the heart of transboundary water politics and its conflicts. To avoid conflicts over transboundary water utilization, seek solutions to existing conflicts, and improve equity, the international community establishes principles, rights, and responsibilities for States through international water law, consisting of interrelated substantive and procedural norms. The substantive norms can be listed briefly as ERU, the no-harm principle, the duty to cooperate, and the obligation to protect the ecosystem. Of these principles, ERU represents customary international law and is undoubtedly now recognized as the pre-eminent rule on upholding the concept of equity in utilizing an international watercourse.Footnote ¹⁶

These substantive norms are operationalized through the general obligation to cooperate, which includes rules of procedure, such as the exchange of data and information, prior notification of planned measures, further consultation on the potential effects of such planned measures, and the mechanisms for dispute settlement. The ERU principle is adopted as the main concept, with other substantive principles employed as secondary concepts.Footnote ¹⁷ Procedural norms are rules on procedures to be followed by concerned parties to fulfil their substantive obligations. These principles form part of the corpus of customary international law, which means they are binding on all States.Footnote ¹⁸

The International Law Commission (ILC) commentary to its 1994 Draft Articles states that the ERU principle is to be applied only in the case of a “conflict of uses”.Footnote ¹⁹ In such cases, where the needs of one or more riparian States are not met because of another State's use of an international watercourse, the ERU principle potentially has an important role in reconciling States’ interests in that watercourse utilization. One question that may arise is how the riparian States should define and agree on the ERU. Without joint management of a shared watercourse, it might be difficult to determine whether it is used equitably and reasonably. The ILC's commentary explains that equitable use applies only to “reasonable and beneficial” uses of international watercourses.Footnote ²⁰ Accordingly, after recognizing a “conflict of interests” over the utilization of an international watercourse and deciding that significant harm is caused, States must first determine whether their use is “reasonable and beneficial”.Footnote ²¹

For this purpose, a “beneficial use” refers to one of economic, social, or cultural value.Footnote ²² However, if the use, though potentially beneficial, offers a low economic or social value, it may not be considered reasonable. In such cases, it is necessary to estimate the benefit of the use, whether economic, social, or cultural and decide whether that use is reasonable. So, what is a “reasonable” use of an international watercourse?

Studies refer to a “contemporary conception of rationality” for determining what is reasonable.Footnote ²³ Although what constitutes a “reasonable” use may vary case by case, in many instances, literature takes a reference to the “vital needs” of States and “sustainable” uses when determining reasonableness.Footnote ²⁴ Therefore, the unsustainable exploitation of water resources would not meet the criteria of reasonable use as declared, for example, by the Sustainable Development Goals of the 2030 United Nations (UN) Agenda for Sustainable Development.Footnote ²⁵ However, while reasonable use relates to the concepts of rationality and sustainability, other factors concerning the degree of a State's development should be considered. This entails a particularly interesting yet demanding task – estimating the development level of a State and how this may affect its reasonable use of an international watercourse. As the International Law Association's commentary on the Helsinki Rules notes,Footnote ²⁶ a developing State should be accorded more time to improve its utilization of an international watercourse than developed States. But giving such a priority may cause conflict; for example, setting up a hydroelectric project in one less-developed upstream State when attempting to advance its economy without considering the interests of downstream States. This dilemma leads McIntyre to propose that there should be a proportionate distribution of benefits from using a shared resource.Footnote ²⁷ This approach could be used to balance legitimate State interests in international watercourses.Footnote ²⁸ Under this approach, States’ current circumstances, including their development level, economic capacity, and needs, should be considered when determining what is “equitable”. Against this backdrop, Article 6(1) of the UN Watercourses Convention lists, non-exhaustively, various factors that should be considered when balancing the interests of States and evaluating ERU:

1. (a) Geographic, hydrographic, hydrological, climatic, ecological and other factors of a natural character;

2. (b) The social and economic needs of the watercourse States concerned;

3. (c) The population dependent on the watercourse in each watercourse State;

4. (d) The effects of the use or uses of the watercourses in one watercourse State on other watercourse States;

5. (e) Existing and potential uses of the watercourse;

6. (f) Conservation, protection, development and economy of use of the water resources of the watercourse and the costs of measures taken to the effect;

7. (g) The availability of alternatives of comparable value to a particular planned or existing use.

Accordingly, in conflicts of (reasonable) uses, resolutions are made based on equity after considering all relevant factors and circumstances.Footnote ²⁹ One important consideration is that vital human needs and the ecosystem of international watercourses should always be protected when establishing a regime for equitable utilization.Footnote ³⁰ Thus, even though the ERU principle might be open to differing States’ interpretations, vital human needs and protection of the ecological system must be guaranteed by law. Such processes must clarify different views on the principles of equitable utilization to provide a common platform and an accepted norm for all actors. Riparian States need to utilize shared water by considering these factors and taking into account the interests of other riparian States, as well as preserving the ecosystem at the shared watercourse.

B. Equity in Practice

The struggles over applying international legal norms to constrain State behaviour may be seen in many international subject areas, such as trade and human rights, in the context of international waters; for example, the debates over the Indus River Basin,Footnote ³¹ the Mekong,Footnote ³² and the Afghanistan dam development. At the end of the 20th century, many international waters in Africa and some in Asia were subject to ill-suited colonial-era arrangements. These political and legal arrangements were designed in ways that mostly favoured imperial interests, leaving the riparian States on their own to align their national interests with ecological reality and continuous socio-economic changes. These arrangements (among them Britain's McMahon arbitration of 1905 for the HRB), in making changes to hydropolitical relations to the advantage of some actors above others, represented an inequitable sharing of the waters in question. Consequently, there remains particular importance attached to differences between the theory, as explained above, and the practice of international water law. In reality, politics and sovereignty are crucial drivers of States’ wishes to control transboundary waters; the ERU principle may be overshadowed by self-interest and may seem ineffective or meaningless or function in favour of the dominant actors involved.

Eckstein remarks that substantive rules of international water law may be used as a political tool in global politics rather than as a legal regime.Footnote ³³ He points out that a legal rule may manifest itself differently depending upon whether it is employed for judicial reasons or for State relations. Since the nature of international water negotiations is identified as ex-ante (based on predicted or anticipated results), substantive international water laws are subjectively used by actors as tools in a political process to further relations. However, these laws are designed to be applied objectively in an ex-post adjudicatory process (based on or decided by actual results).Footnote ³⁴ Woodhouse and Zeitoun observe that, in practice, States have used these laws to strengthen their negotiating positions, mainly to the advantage of powerful States, despite them being intended to protect the weaker party.Footnote ³⁵ Thus, they suggest that the role of power asymmetry in legitimizing transboundary water arrangements should be accounted for in “critical” hydropolitical studies.

What is significant here is how the ERU principle, which is expected to strike a balance among various social, economic, and environmental interests of different parties, can be interpreted and implemented differently within a complex political context. In such unequal conditions, even if equity is the ultimate goal of hydropolitical relations, the perception and interpretation of the concept of equity differ from one State to another, often coloured by the dominant power structure and influenced by their interests and identity. As will be shown in this paper, equity in transboundary waters is almost always sacrificed for the sake of the security interests driven by broader geopolitical dynamics. Correspondingly, this influences the ability of States to shape and control the “rules of the game”. Therefore, interpreting and implementing legal principles, such as the ERU principle, without acknowledging political intent would be unwise. I follow these lines of thought to analyse the legal arrangements of the HRB in light of the ERU principle.

A. Goldsmid and McMahon Arbitrations

The first arrangements for water between Afghanistan and Iran were prompted by imperialist rivalry over sovereignty and territorial boundaries in the late 19th century.Footnote ⁴³ By the end of the Anglo-Persian War (1856–7), and under the rivalry of the Great Game between the British Empire and Russia, the 1857 Treaty of Peace (the Paris Treaty) between Persia and Great Britain was signed. Under its terms, Persia was obliged to relinquish all claims to Herat by acknowledging the independence of Afghanistan under British suzerainty, and Britain agreed to serve as the arbiter of disputes between Persia and Afghanistan “in a manner just and honourable to Persia”.Footnote ⁴⁴ As a result, in 1872,Footnote ⁴⁵ a British officer, General Sir Frederic Goldsmid,Footnote ⁴⁶ acted for Britain in arbitrating a dispute between Iran and Afghanistan over the delimitation of the boundary at the border region of Sistan, where the delta of the Helmand River is located. A decision was made to delineate the main branch of the Helmand River in the delta region, with the principal irrigation areas and the major population at the time remaining on one side of the newly established border. Persia and the supply canals necessary for those Persian irrigations were assigned to the other side of the border, Afghanistan.Footnote ⁴⁷ The problem with Goldsmid's settlement was the lack of any decision on, or recommendation for, a mechanism for water division between the two newly divided sides. He offered only the general advice: “It is, moreover, to be well understood that no works are to be carried out on either side calculated to interfere with the requisite supply of water for irrigation on the banks of the Helmand.”Footnote ⁴⁸ Moreover, he did not consider the natural effects of changes in river morphology and their consequent influence on the political border. The result of Goldsmid's arbitration may look unfair to Iran as it simply left downstream Iran's serious water allocation concern unresolved with high uncertainty.

Although the question of water allocation remained unanswered in Goldsmid's arbitration, controversies over the Helmand waters in the delta were, apparently, settled locally.Footnote ⁴⁹ However, further disputes between the two countries occurred in 1896, mainly because the river changed its course at the border area following flooding, after which a severe drought occurred. In 1903, the British assigned Colonel Sir Henry McMahon to demarcate new boundaries and determine water rights. Relating to the water allocation between the two sides, it seems that McMahon first ruled that the Helmand water should be divided equally between the two parties in the border area in 1903–4. However, in 1905, McMahon decided to allocate two-thirds of the Helmand water in the delta to Afghanistan and the remaining third to Iran; the water demand of the Hamoun wetlands was neglected in his arbitration (indeed, the environment was not considered an important issue at the time).Footnote ⁵⁰ While both parties accepted the decision relating to political borders, Iran objected to McMahon's compromise on water allocation at that time. While the reasons for McMahon's change are not clear from the literature, the correctness of the arbitration outcome could potentially be questioned since the Iranian side of the boundary was at that time broader, more fertile, and more populous than the Afghan side in the province of Nimroz, even without taking into consideration the needs of the Hamoun wetlands themselves.Footnote ⁵¹ The arbitration outcome could be interpreted as a deliberate British tactic to keep Afghanistan as a buffer State under their control.

One interesting observation is that, despite the geopolitical shadow cast over the HRB, the idea of equitable utilization was cited as the basis for the first attempts in the 1870s to resolve the water disputes between Afghanistan and Iran over the Helmand River.Footnote ⁵² However, from a political point of view, allowing Afghanistan potentially complete control of the water while under British suzerainty and serving as a “buffer State” against Russia by separating the major water demand in Persia from the total water supply in Afghanistan meant that the Goldsmid arbitration could be seen to favour Great Britain in the broader scheme of things.Footnote ⁵³ Therefore, even if it is agreed that the arbitrations were based on equitable considerations, the British imposed, at best, a very narrow legal regime of “equitable” utilization by placing the water tap in Afghanistan, apparently to protect their security interest in colonized India, the “jewel in the crown”. However, apart from this political interpretation, from a legal perspective, it seems at first glance, as McCaffrey points out, that the Goldsmid arbitration was based on a “no significant harm” principle rather than the ERU principle, as it did not interfere with existing water allocations between Afghanistan and Persia: that is, “no works are to be carried out on either side”.Footnote ⁵⁴

Notwithstanding this, it must be put into context to understand and interpret the Goldsmid Award. First, most of the water demand – for irrigation and the population – was on the Persian side.Footnote ⁵⁵ Second, the award did not explicitly determine water division between the two sides, instead being limited to a general statement on preserving all the existing uses and the “requisite supply of water for irrigation” for both sides of the Helmand. Accordingly, as McCaffrey and Lammers note, the Goldsmid Award seems to have been based principally on the equitable considerations of the time.Footnote ⁵⁶ However, this semi-colonial and limited view of ERU soon ended in failure because it did not accurately and clearly account for changing circumstances, including the future development interests of Afghanistan and the effects on downstream Iran. Moreover, the arbitration award did not provide a specific solution for parties to deal with times of flood and especially drought – the extreme events that ultimately consigned the arbitration to failure. Legal arrangements of this nature were primarily politically oriented tools designed solely to serve the security interests of the arbitrator. In addition to the lack of sufficient consideration of the ERU principle, these legal arrangements did not sufficiently consider the need for clarity and constancy (or predictability), which are some of the “criteria of legality” described by Brunnée and Toope.Footnote ⁵⁷

B. The 1973 Helmand Treaty

The negotiations between Afghanistan and Iran over the utilization of the Helmand River continued into the 20th century during the post-colonial period, despite their changing fortunes due to international political competition during the Cold War. In the 1940s, the disputes were revived, particularly after the US-funded Helmand-Arghandab Valley Authority [HAVA] was formed. As part of the “new Great Game”, the United States pursued a similar geopolitical goal as the British had earlier – to maintain Afghanistan as a buffer State – though with the intent of making it a “development” model for the whole world.Footnote ⁵⁸ The US project in the HRB involved the construction of diversion dams and canals on the river in accordance with contracts made with the Afghans in 1945. Iran opposed the HAVA project and, after experiencing low water flow and drought in the downstream Sistan region, Iran decided to call on the UN Security Council to step into the water disputes with Afghanistan. The United States offered to mediate the Afghanistan-Iran water dispute over the renewed, securitized Helmand River.Footnote ⁵⁹ However, the fairness of the mediation by the United States could have been tainted by a conflict of interest because they wanted to build the dams and canals for the HAVA project for the Afghan government using a North American company, Morrison-Knudson.

The US proposal was based on creating a “neutral” commission of international experts from “disinterested countries” to study technical aspects of the water allocation problem, aiming to establish an engineering project agreed upon by Afghanistan and Iran.Footnote ⁶⁰ It was for this reason that Iran and Afghanistan created the Helmand River Delta Commission in 1948. The Commission was established with the sole purpose of recommending “an engineering basis for mutual accord regarding the apportionment of the waters of the Helmand River”.Footnote ⁶¹ The function of the Delta Commission as a “fact-finding body” was to “collect and study available data”,Footnote ⁶² including stream flow and natural characteristics (floods and droughts) of the river, past and present uses in the delta area, existing works and plans for new installations, and to develop more scientific methods to use available waters. But while Afghanistan expressed its satisfaction almost immediately after the Delta Commission published its report, Iran rejected the results. The Iranian rejection was mainly based on disagreement with the report's estimated number of irrigation lands in Sistan, an argument it had similarly made against McMahon's Award.Footnote ⁶³

Almost twenty years after the failed US arbitration, and again following a severe drought in the downstream part of the river in 1970–1, the two countries finally signed the Helmand River Water Treaty in 1973.Footnote ⁶⁴ The 1973 Treaty is based on the 1951 Helmand River Delta Commission report that Iran had initially rejected. Many argue that the 1973 Treaty emerged from “hidden” talks during the Cold War and was a “gift” from the United States (and Iran) to Afghanistan to stand against the (Russian) communists.Footnote ⁶⁵ Forged under such extreme geopolitical rivalry, it is not far beyond expectation that the robustness of the 1973 Treaty is not just deeply flawed; the extent to which the ERU principle is considered also seems to be poor. Consequently, one may argue that the Treaty, at best, contributed to a much shorter “life cycle of norms”, as described by Brunnée and Toope.Footnote ⁶⁶ This argument merits further investigation.

The Helmand River Delta Commission, from which the 1973 Treaty was inspired, aimed to provide “an equitable apportionment of the waters on the Helmand River”.Footnote ⁶⁷ In addition, as noted by McCaffrey, the list of indicative factors for fact-finding by the Delta Commission “parallels strikingly the list of factors relevant to equitable utilization contained in Article 6 of the UN Convention”.Footnote ⁶⁸ However, the 1973 Treaty does not explicitly allude to the principle of ERU, even though it often plays “the lead role” in planned water measures.Footnote ⁶⁹ Therefore, it is reasonable to raise this paper's core question: to what extent does the 1973 Treaty reflect the criteria of ERU?

A. Content

Of the two competing models of equitable utilization at an international watercourse – one being “classic apportionment”, the other “shared benefits”Footnote ⁷³ – the former apparently provided the basis of the 1973 Helmand River Water Treaty, leaving riparian States at liberty to unilaterally use their share. However, a decision was made on the fairness of the overall water amount to be used. The 1973 Treaty contained twelve Articles, with two protocols related to Articles VIII and IX. Article I(c) identifies a “normal water year” as the year during which the total volume of water from the 1st of October to the end of September the next year is 5661.71 MCM, as measured and calculated at the hydrometric station of Dehrawud, upstream of the Kajakai Dam. The 1973 Treaty relied on the previous Delta Commission's recommendations that allocated water primarily for irrigation purposes, which Iran had initially rejected. According to the 1973 Treaty, Afghanistan must supply Iran with an average of 22 cubic meters per second, with an additional 4 cubic meters per second for “goodwill and brotherly relations” in a normal (or above normal) water year.Footnote ⁷⁴ This amounts to about 820 MCM per year, or only 8.5% of the average surface water availability of 9,552 MCM in the whole basin, or 14% of 5,661.71 MCM as measured at the Dehrawud station, and less than 14% of the overall water demand and requirement in Sistan.Footnote ⁷⁵ In short, this was less water than any of the previous legal arrangements.Footnote ⁷⁶ To contend with the conflicts over the Helmand waters and to implement the Treaty's provisions, Article VIII directs each party to appoint a commissioner and deputy commissioner as part of the Helmand River Commission (HRC). The first protocol of the Treaty sets out the commissioners’ authority and functions.

Since the core of the Treaty is to agree on Iran's water allocation (for agriculture), Article V gives priority to meeting Iran's water rights based on Articles II, III, and IV of the Treaty. Nevertheless, the challenge is to resolve a paradox in the Treaty since paragraph two of Article V of the Treaty gives almost complete freedom to Afghanistan to utilize the Helmand water (after Iran gets its allocation) subject to the following conditions:

Furthermore, some challenges, such as climate change, new developments planned with poor water management schemes, changing socio-economic patterns, and increasing environmental degradation on both sides of the HRB, have not only complicated the management of transboundary waters under the 1973 Treaty but have also hindered the resolution of the conflict towards ERU.

B. The Role of Physical Factors

To start with relevant ERU factors, among other elements, it is important to discuss the physical features of international watercourses – for example, hydrological and geographical characteristics – since these physical features often arise in controversial debates on equitable water allocation, particularly in the case of the Helmand River between Afghanistan and Iran. Physical factors play significant roles in bilateral bargaining between both sides of the HRB. Specific discourses, such as “our country contributes more waters in the flow” or “the river passes a longer way through our lands”, are still used to bargain over the utilization of waters within the modern, “right-based” realm to legitimize certain acts or claims. These discourses are present in the current controversial debate over the case of the Helmand River, resulting in the confrontation of two outdated doctrines of “absolute sovereignty”. Generally, even though geographical and hydrological factors are the first to be set down in most codifications, it would appear from judicial and State practice that they rank low in the hierarchy of factors relevant to equitable utilization.Footnote ⁷⁷ Concerning these factors, State practice also suggests that “river frontage” has rarely been invoked as a basis for determining an equitable regime for the utilization of an international river.Footnote ⁷⁸ Besides, the extent of the “drainage area” would appear to lack significance, similar to river frontage.Footnote ⁷⁹

In some comparable situations, such physical factors play only a secondary role in attempts at “equitable utilization”.Footnote ⁸⁰ In the case of the Colorado River, for instance, which flows through Mexico for just 100 miles (some way less than 10% of its 1,300-mile total length), the portion of the river flowing through the respective territories of Mexico and the US was never considered as a basis for the allocation of waters.Footnote ⁸¹ Similarly, in the dispute concerning the Narmada River (central India), the Indian states of Gujarat and Madhya Pradesh hosted 14% and 86% of the drainage basin but were allocated 33% and 67% of its waters, respectively.Footnote ⁸² Thus, physical factors are undoubtedly given less weight in certain circumstances.Footnote ⁸³

In the case of the Helmand River, about 85% of its length is in Afghanistan. Thus, some Afghans strongly believe that it is entirely a “national” and “internal” river flowing only in Afghan territory and take this as their bargaining position.Footnote ⁸⁴ In this regard, Mojtahed-Zadeh points out:Footnote ⁸⁵

McMahon's Memorandum of 25 September 1904 asserts: “The Afghan Government does not admit that there is any water question in dispute, as their geographical position makes them sole owner of the whole Helmand above the Band-i-Sistan”.

In the same vein, some in Iran assert that most water utilization historically occurred downstream of the river (currently located at Sistan on the Iranian side and Nimroz on the Afghan side, surrounding the Hamoun wetlands). However, from a legal perspective, none of these narratives is necessary to allocate the rights to water utilization equitably and reasonably. When surveying all court decisions on transboundary river cases worldwide, the physical factors of shared water basins have mostly been secondary considerations compared with other features; for example, environmental, economic, and social needs. In other words, the primary considerations of equitable utilization revolve around vital human needs, including social and economic needs and the protection of ecosystems, not physical geography.

C. Socio-Economic Factors

Social and economic needs are prominent considerations when determining ERU. The Helmand River plays a significant role in water-scarce regions of both Afghanistan and Iran and has made an essential contribution to the livelihood of the surrounding inhabitants. While Afghanistan, low on the Human Development Index (HDI), sees its water resources as a strategic reserve with which to further its economy and help lift its population out of poverty, Iran needs the same water to safeguard its population's drinking demand and agricultural activity in Sistan, which has a fragile economy and no other available water. In this case, the 1973 Treaty does not provide a platform for the cooperation, monitoring, or exchange of reliable data with which to examine the social and economic criteria on both sides to estimate how far their utilization is consistent with the ERU principle. As there is no other alternative to the 1973 Treaty, it is difficult to find a clear solution. Examining the 1973 Treaty with the modern understanding of the ERU principle, the 1973 Treaty, which was based on the calculation of the Delta Commission and was limited to the irrigation requirements from the Helmand River, seems to overlook other socio-economic considerations downstream of the basin; for example, the importance of the river for fishing and navigation, but note that some of the dependent population were ignored. Being lower on the HDI than Iran, Afghanistan may have a stronger argument based on social and economic factors. This gives rise to a customary debate on balancing the utilization of water for development/economic prosperity at the upstream, taking into account the needs of the downstream while protecting the ecosystem and vital human rights. Having neglected such important issues, the 1973 Treaty remains static with rigid rules on mere water division, which is not consistent with the ERU principle.

D. Vital Human Needs and Environmental Protection

In the assessment of conditions relevant to the ERU principle, although no use enjoys inherent priority, “special regard” is paid to “vital human needs” in Article 10(2) of the Watercourses Convention. Therefore, if a use threatens the availability of water sufficient to sustain human life consistent with an individual's right to water, it is considered inequitable.Footnote ⁸⁶ Additionally, in weighing up considerations relevant to the ERU principle, the protection of an ecosystem finds increasing support. On the obligation to protect the ecosystems of an international watercourse, Article 20 of the Watercourses Convention, as “a simple, but potentially powerful, provision”,Footnote ⁸⁷ instructs that “watercourse States shall, individually and, where appropriate, jointly, protect and preserve the ecosystems of international watercourses”.

Viewing the case of the Helmand River through the lens of Integrated Water Resources Management and River Basin Management, Thomas and Varzi show how the 1951 Delta Commission, on which, as noted above, the 1973 Treaty was established, underestimated the water demands of the Hamoun wetlands in its calculations.Footnote ⁸⁸ They observe that the Treaty failed to appreciate the integrity of the “agro-ecological system” in the Sistan Delta. While the Delta Commission considered water for irrigation as “beneficial”, the water entering the Hamoun wetlands was described as “waste water”.Footnote ⁸⁹ No such specific issue is explicitly stated in the 1973 Treaty, but Article II acknowledges that the total amount of water from the Helmand River to be delivered to Iran by Afghanistan accords with the report of the Helmand River Delta Commission. Accordingly, considering the contemporary importance of environmental protection in defining the ERU principle, the 1973 Helmand Treaty seems to be demonstrably misleading and factually wrong by focusing only on the demand for irrigation water. The water to sustain the wetlands, on which the population of the Sistan (and the delta on both sides of the border) is dependent, was labelled “waste”.

While the 1973 Treaty allows some water for Iran's irrigation and preserves Afghanistan's right to unilateral water development, it leaves the ecosystems of the HRB unprotected, the social and economic welfare of the population surrounding the Hamoun wetlands vulnerable, and the sustainability of the whole basin at risk. Consequently, the Treaty could be censured as a breach of the ERU principle in two important ways: failing to protect vital human needs and the ecosystems of the HRB. The obligation to protect ecosystems is also closely connected to the obligation of maintaining the minimum environmental flow, which is now recognized in general international water law. The obligation of environmental flows, an important feature of ERU, has also received significant support from recent arbitral and judicial decisions; see the case of Kishenganga Arbitration (Pakistan v. India).Footnote ⁹⁰ The 1973 Treaty does not ensure minimum environmental flows, leaving the downstream ecosystem vulnerable, particularly in times of drought and upstream development in Afghanistan or Iran. This is substantiated by the scientific findings of other studies investigating the role of development at upstream Afghanistan and in the degradation of the Hamoun wetlands, which discovered that dams and, more importantly, massive irrigation expansion, including opium cultivation during the conflict in Afghanistan, had contributed to this deterioration.Footnote ⁹¹ However, it should be noted that Iran's utilization of the same waters also needs to be considered when studying the degradation of the HRB's ecosystems, particularly the Hamoun wetlands. Several other factors should also be considered to understand better why the Hamoun wetlands are nearly dried up, which includes unsustainable agriculture and extensive canal creation on both sides, Iran's diversion of the Helmand River water to Chahnimeh, massive opium cultivation, and groundwater consumption in Afghanistan.Footnote ⁹²

The ERU principle is accompanied by a procedural obligation to cooperate and to conduct a transboundary Environmental Impact Assessment of projects before permitting them. Both Afghanistan and Iran argue that their water development is based on the rights afforded to them by the bilateral Treaty and that it complies with the ERU principle. However, the practice of the riparian States of the HRB is dominated by an insistence on unilateral actions without any exchange of data or cooperation on the protection of the Hamoun wetlands.Footnote ⁹³ The efforts of international organizations, particularly UNESCO, the Ramsar Convention, the UN Development Programme, the UN Environment Programme, and the Global Environment Facility, have failed to create an integrative regional/basin-wide plan for cooperation and management of the Helmand River and the protection of the Hamoun wetlands.Footnote ⁹⁴ Iran's invitation to register and protect the whole Hamoun wetlands under the Ramsar Convention and the latest proposal in 2020 for conducting a joint study did not receive a positive response from Afghanistan. Therefore, whether Afghanistan or Iran is committed to the Treaty or complies with the ERU principle is unclear.

Iran and Afghanistan have an equal duty to protect and preserve the ecosystems of the HRB and have a shared responsibility for liability and compensation for environmental damage caused by their activities within and beyond their jurisdiction. However, protecting the Hamoun wetlands without the cooperation of Afghanistan (as the main water source) is either unfeasible or inadequate for downstream Iran. In this respect, the 1973 Treaty lacks the essential components to oblige riparian States to cooperate and to give adequate notification of planned works, making it very difficult to apply the ERU principle. Furthermore, even though the 1973 Treaty does not explicitly deal with the responsibilities of both States concerning the human right to water, all States are obliged to respect the human right to water according to their duties (including positive and negative obligations) under international human rights law: this is increasingly recognized by both the international community and authoritative human rights bodies. While there is a debate on whether a substantive universal human right to water exists, some legal scholars believe that under Articles 11(1) and 12(1) of the 1966 International Covenant on Economic, Social and Cultural Rights (ICESCR), the human right to water is legally binding. General Comment 15 – adopted in 2002 by the UN Committee on Economic, Social and Cultural Rights (CESCR), which monitors the implementation of the ICESCR – declares that “the human right to water is indispensable for leading a life in human dignity. It is a prerequisite for the realization of other human rights.” Footnote ⁹⁵ Both Iran and Afghanistan ratified and acceded to the ICESCR. However, given the significant transboundary damage resulting from both States’ activities, the 1973 Treaty is not in line with the obligations to assure the rights of individuals under international human rights law. Accordingly, the current utilization of the HRB is not consistent with established legal principles and practices.

In sum, the 1973 Treaty lacks the potential to tackle the actual water problems within an integrated basin-wide framework and cannot satisfy the interests of both riparian States. The 1973 Treaty is an agreement only for issue-specific water division – that is, irrigation – and it does not meet all the demands in the basin, particularly for environmental protection, nor does it reflect a basin-wide view. In fact, by ignoring the importance of vital human needs and ecological/environmental protection, the 1973 Treaty does not have the strong legal, institutional, and conventional ability to balance the water control and development requirements in upstream Afghanistan or the ecological demand downstream of the basin. Therefore, the 1973 Treaty seems ill-equipped to cope with water conflicts at the Helmand River and is ill-suited, being “a matter of misplaced faith in formal rules”,Footnote ⁹⁶ to guide relations between Afghanistan and Iran for equitable utilization of the HRB.