2021/69 “The Mekong River Ecosystem in Crisis: ASEAN Cannot be a Bystander” by Hoang Thi Ha and Farah Nadine Seth

The Mekong River ecosystem is on the verge of irreversible collapse due to the accumulative effects of climate change and increased numbers of upstream dams as well as other human-made activities such as deforestation, sand mining, extensive irrigation for agriculture and wetland conversion. In this picture, fishers pull in their fishing nets as the sun rises over the Mekong River in Phnom Penh on June 9, 2020. Photo: TANG CHHIN Sothy, AFP.


  • Despite being the premier regional organisation in Southeast Asia, ASEAN remains a bystander in the imminent collapse of the Mekong River ecosystem which runs through five of its member states.
  • ASEAN’s compartmentalised sub-regional approach characterises and justifies its heretofore indifference to Mekong environmental woes despite their impact on the region’s food security and climate change action.
  • The successful mainstreaming of transboundary haze pollution in ASEAN’s legal and institutional frameworks should be an instructive example for invigorating ASEAN’s engagement in the Mekong issues.
  • Most ASEAN member states remain reluctant to place Mekong issues on the regional agenda due to their sensitivity towards China and their reluctance to be embroiled in geopolitical competition in the Mekong basin. 
  • To stay relevant and central to the region, ASEAN needs to recognise its stakes in the Mekong basin by overcoming its current sub-regional mentality and by embracing Southeast Asia in its totality as a strategic theatre.

* Hoang Thi Ha is Fellow and Lead Researcher (Political-Security Affairs) and Farah Nadine Seth is Research Officer at the ASEAN Studies Centre, ISEAS – Yusof Ishak Institute.


The Mekong River runs from the Tibetan Plateau through China, Myanmar, Laos, Thailand, Cambodia and Vietnam before discharging into the South China Sea. The territory of Laos covers 25% of the Mekong basin, followed by Thailand (23%), China (21%), Cambodia (20%), Vietnam (8%) and Myanmar (3%).[1] The Mekong basin is one of the richest areas of biodiversity in the world, sustaining around 66 million people, i.e. 10% of ASEAN’s total population, including “most of the population of Laos and Cambodia, one-third of Thailand’s 65 million, and one-fifth of Vietnam’s 90 million people.”[2]

ASEAN’s expansion to include all Southeast Asian mainland states in the 1990s brought the Mekong region well within the grouping’s geographical coverage. Upon its enlargement, ASEAN’s focus was not on the river system itself but on narrowing the development gap between the old and the new member states, namely Cambodia, Laos, Myanmar and Vietnam (CLMV). In 1996, ASEAN established the ASEAN-Mekong Basin Development Cooperation (AMBDC), which included China among its members. One of the AMBDC’s objectives was to “strengthen the interconnections and economic linkages between the ASEAN member countries and the Mekong riparian countries”.[3] The AMBDC, however, gradually lost its momentum and became inactive, with no ministerial meeting convened since 2014. ASEAN’s well-intentioned developmental approach that focused on connectivity and trade with the Mekong sub-region never quite took off because the grouping did not have the economic mass to finance its initiatives. The AMBDC’s flagship project Singapore-Kunming Rail Link (SKRL) made little headway and headline for two decades until China made a splash in recent years with a number of high-speed train projects under its Belt and Road Initiative (BRI).

ASEAN’s approach towards the Mekong region has thus far been consigned to the sub-regional category that receives ASEAN’s implicit blessing but does not fall under its active institutional purview. These sub-regional frameworks cover both maritime and mainland Southeast Asia, including the Brunei-Indonesia-Malaysia-Philippines-East ASEAN Growth Area (BIMP-EAGA), the Riau islands Indonesia-Malaysia-Singapore Growth Triangle, the Indonesia-Malaysia-Thailand Growth Triangle (IMT-GT), the Ayeyawady-Chao Phraya-Mekong Economic Cooperation Strategy (ACMECS), the CLMV Cooperation, and the Cambodia, Laos, Vietnam Development Triangle Area (CLV), among others. These frameworks have a development-connectivity focus with a view to linking “geographically proximate areas with different factor endowments, and hence different comparative advantages, to form an economically dynamic sub-region”.[4]

Although this sub-regional approach makes economic sense, it is often used to excuse ASEAN from taking a more proactive role where Mekong-related issues are concerned.[5] As the regional grouping, ASEAN remains a marginal player with regard to a multitude of environmental challenges and geopolitical developments unfolding in the Mekong basin. As ASEAN continues to stand on the side-lines, other Mekong-related frameworks initiated by various major powers have sprouted up, in keeping with the growing economic, environmental and strategic importance of the sub-region. These include, among others, the China-led Lancang-Mekong Cooperation (LMC), the Mekong-US Partnership (expanded from the earlier Lower Mekong Initiative), the Mekong-Republic of Korea Cooperation (Mekong-ROK), the India-led Mekong-Ganga Cooperation (MGC), the Mekong-Japan Cooperation (MJC), and most recently the Japan-US Mekong Power Partnership (JUMPP).

In 2020, Vietnam tried to utilise its ASEAN chairmanship to bring Mekong issues into ASEAN’s agenda, but with very limited success.[6] Hanoi’s attempt to mainstream the Mekong into the ASEAN-wide discourse met with reservations from some maritime and mainland Southeast Asian states for different reasons.[7] For maritime ASEAN states, the Mekong issues are viewed from the sub-regional lens – i.e. they affect only the mainland states and should be best addressed through their existing sub-regional frameworks.

This Perspective challenges this sub-regional approach to the Mekong issues on two accounts: (i) The impact of the environmental crisis in the Mekong River ecosystem goes beyond the sub-regional confines and affects ASEAN’s food security and climate change action as a whole; and (ii) The transboundary haze pollution provides an instructive precedent in mobilising ASEAN frameworks for an essentially sub-regional problem. This article also examines the geopolitical considerations that underlie the reluctance of most ASEAN member states to include Mekong issues in ASEAN’s agenda, hence their default relegation to sub-regional mechanisms.


In the final passage of his book “Last Days of the Mighty Mekong” published in 2019, Brian Eyler highlights the concept of connectivity – i.e. “the river itself doesn’t have an Upper or Lower Mekong. The system is one” – as the most potent paradigm shift to save the drying Mekong River.[8] The connectivity concept should likewise apply to lift ASEAN out of its “bystander” mode with regard to the unfolding ecological and environmental crisis in the Mekong basin which has taken on an unprecedented level of urgency in recent years.

The Mekong River ecosystem is on the verge of irreversible collapse due to the accumulative effects of climate change and increased numbers of upstream dams as well as other human-made activities such as deforestation, sand mining, extensive irrigation for agriculture and wetland conversion. In 2019, severe droughts caused water levels in the river to drop to their lowest in more than 100 years.[9] Low inflows from the Mekong and its tributaries in the summer of 2020 sent the water volume of Cambodia’s Tonle Sap Lake down to a “very critical situation”, according to the Mekong River Commission (MRC).[10]

The changing hydrological conditions of the Mekong River with unpredictable droughts and floods and reduced river sediments have wreaked havoc on agricultural production and inland fishery. Tonle Sap Lake accounts for two-thirds of Cambodia’s fish-catch – the main source of its population’s protein intake. Yet, increasing numbers of local fishers have reported dwindling fish catches. In December 2020, Cambodia’s Ministry of Agriculture, Forestry and Fisheries announced that the freshwater fish catch among some of the country’s licensed fishers dropped by 31% compared to 2019.[11] In the first quarter of 2021, freshwater fisheries along the Tonle Sap river yielded 1,310 tonnes, a decrease of 190 tonnes while freshwater products caught by families were 56,800 tonnes, a decrease of 12,600 tonnes.[12] Meanwhile, in early 2020, Vietnam’s Mekong Delta suffered its worst drought and saltwater intrusion which affected 42.5% of its land area, or 1,688,600 hectares, a steep increase from 2016’s 50,376 hectares.[13] The river sediment reaching the delta is estimated to be a third of what it was in 2007, critically impacting the country’s agricultural production.[14] The delta produces more than 50% of Vietnam’s rice output and 60% of its total fishery.[15]

According to the State of Southeast Asia: 2021 Survey Report by the ASEAN Studies Centre of ISEAS – Yusof Ishak Institute, many Southeast Asians are concerned about the Mekong’s environmental problems and their impact on regional food security, which underlie their support for ASEAN to pay greater attention to the Mekong. 72.2% of the survey’s 1,032 respondents agreed that ASEAN should include Mekong River issues in its agenda. This sentiment was not only pronounced in the downstream riparian states, namely Vietnam (92.6%), Thailand (87.8%) and Cambodia (73%), but also in maritime Southeast Asian states such as Singapore (74%), Malaysia (67.5%) and the Philippines (67.2%).[16] The survey results demonstrate that food security challenges in the Mekong basin are a cause for region-wide concern because these riparian countries are among the world’s biggest rice exporters, including to maritime ASEAN states (Table 1).

Given the transboundary impact of the Mekong environmental degradation, especially on regional food security systems and forced migrations to urban centres and neighbouring states, ASEAN needs to revisit the arbitrary distinction between ‘sub-region’ and ‘region’ that has characterised and justified its heretofore indifference to the Mekong problems. Apart from food security, the Mekong ecosystem is an indispensable part of ASEAN’s climate change action going forward. The climate change impact and adaptation measures by the Mekong riparian states should be synergised with similar undertakings in other parts of the region. One example is the recommendation that the Mekong basin climate monitoring system set up by the MRC to disseminate data on the hydrological conditions of the river be built upon for extension in the Philippines and other southern parts of Southeast Asia.[17]


ASEAN set a precedent when it mainstreamed transboundary haze pollution into its regional agenda. Before the 1990s, haze pollution caused by land and forest fires in Indonesia had been largely dealt with at the sub-regional or bilateral levels between directly affected countries, namely Brunei, Indonesia, Malaysia and Singapore.  However, dangerous levels of smoke haze blanketing maritime Southeast Asia in the mid-1990s transformed the largely sub-regional transboundary pollution issue into an ASEAN-wide concern.

As the most seriously affected countries, Singapore and Malaysia took the lead in regionalising the haze problem and pushing forward a coordinated ASEAN approach in this respect. In 1994, Malaysia and Singapore’s joint proposal for a regional early haze warning system was adopted at the First Informal ASEAN Ministerial Meeting on the Environment in Sarawak, Malaysia. In 1995, ASEAN passed the Cooperation Plan on Transboundary Pollution with haze mitigation as one of its central tenets. Shortly after, the Haze Technical Task Force (HTTF) was established. These initiatives set out measures for expertise-sharing and capacity-building between ASEAN countries to mitigate haze and forest fires, while strengthening haze monitoring and warning systems.[18]

Following the dangerous haze pollution which blanketed maritime Southeast Asia for months in 1997, the ASEAN Ministerial Meeting on Haze was established, according transboundary haze a position of importance under a dedicated ASEAN ministerial body.[19] The signing of the ASEAN Agreement on Transboundary Haze Pollution (AATHP) in 2002[20] was the culmination of decade-long efforts by the affected states in leveraging ASEAN frameworks to address the transboundary haze issue. Such efforts are attributed to these states’ realisation that a multilateral ASEAN approach was needed due to limited levers at the domestic level to counter the transboundary pollution and the need for burden-sharing in mitigation actions.[21]

Having ASEAN in the game levelled up the peer-group pressure and the effect of suasion vis-à-vis Indonesia, the source country of the haze but also a big neighbour with which Singapore must handle bilateral ties with care. In this regard, ASEAN was considered “the best platform for Singapore to channel pressure and help to Indonesia, without seeming overly condescending”.[22] Although it has been rightly pointed out that haze management in ASEAN has been less effective given the constraint of the ASEAN Way,[23] the achievement of a common regional approach to haze should not be underestimated. As in the case of many other regional challenges, ASEAN is not meant to be the solution but part of the efforts towards reaching a solution. As remarked by the late Southeast Asia scholar Michael Leifer, “regionalism is not a ready-made panacea for security and prosperity but merely an approach to such ends with possibilities for success.”[24]

Given the precedent set with the mainstreaming of the haze issue in the region-wide agenda, consigning the Mekong environmental crisis to a sub-regional category to justify ASEAN’s non-engagement does not hold water. Mainland ASEAN states rose to the call when its maritime counterparts pushed for a more regional approach to the haze problem. Myanmar, Thailand and Vietnam joined Singapore, Malaysia and Brunei in ratifying the AATHP early to enable its entry into force in November 2003. Given the urgency of the Mekong ecosystem’s imminent catastrophe, it is time that maritime ASEAN members revisit their detached approach now when it is mainland Southeast Asia that “catches fire”.

Of note, ASEAN’s region-wide instruments on haze action do not supplant but supplement and support existing sub-regional arrangements. There are two Sub-regional Ministerial Steering Committees on Transboundary Haze Pollution (MSCs) for the southern circuit (maritime states plus Thailand) and northern circuit (CLMV plus Thailand). These MSCs meet annually and discuss practical actions that are tailored to their sub-regions, and then report back to the Conference of the Parties (COP) to the AATHP.[25] This regional–sub-regional synergy is instructive for ASEAN to step up its engagement on the Mekong. 



ASEAN’s approach to the transboundary haze pollution provides an instructive precedent to help overcome the sub-regional mentality in addressing transboundary issues in the region. However, geopolitics sets the Mekong River apart and makes it far more complicated and difficult for ASEAN to take a forward-leaning approach. The transboundary haze issue is confined to ‘low politics’ and can be neatly placed under the environment sector. The Mekong issues represent a cocktail of low and high politics that involve water resources management, energy development, food security, economic connectivity as well as geopolitical competition.  For the haze issue, one mainly has to deal with non-state actors, e.g. plantation owners clearing forests for commercial use and small farmers doing slash-and-burn agriculture. For the Mekong challenge, one has to live with an ascending great power which not only controls the river’s headwaters but also wields predominant economic and strategic influence over all ASEAN member states, especially those in the mainland. 

With the exception of Vietnam, most Southeast Asian states remain reluctant to put the Mekong issues onto ASEAN’s agenda for fear of displeasing Beijing. China has built 11 dams in the Upper Mekong and Chinese companies are involved in numerous hydropower projects downstream, especially in Laos. The most recent study of these upstream dams’ impact on the Mekong’s natural flows is The Eyes on Earth report from April 2020. The report concludes that “the severe lack of water in the Lower Mekong during the wet seasons of 2019 is largely influenced by the restriction of water flowing from the Upper Mekong during that time.”[26] China has since disputed the findings of the report. The MRC also released a critique of the report and appealed to the Mekong countries to share data and information on water use and infrastructure operation.[27] The Vientiane Declaration of the third LMC Leaders’ Meeting in August last year hardly addressed the damming issue other than with a fleeting mention of “dam safety”. The document instead focused on climate change, cross-border trade and inter-regional connectivity including power connectivity and power trade.[28]

The increased interest and involvement in the Mekong basin by other major powers, especially the US, also add to this sensitivity of the ASEAN states. Most do not want to be embroiled in another arena of major power competition over yet another body of water apart from the South China Sea. On top of that, there is a competitive dynamic at play as some maritime ASEAN states would not want to see external attention and resources flow into the Mekong basin at the expense of their own sub-regional frameworks such as the BIMP-EAGA. Keeping the Mekong issues within the confines of sub-regional frameworks therefore conveniently justifies ASEAN’s detachment from Mekong geopolitics.

This apathy toward the Mekong issues, especially on the part of non-riparian ASEAN states, represents “a narrow transactional approach” that fails to grasp “Southeast Asia holistically as one strategic theater”, according to Bilahari Kausikan.[29] The coming together of ‘one Southeast Asia’ with ASEAN being its premier regional organisation has become even more fraught with the return of major power rivalry and the deepening of political-strategic incoherence within ASEAN. From the South China Sea issue to the ongoing Myanmar crisis, ASEAN is becoming increasingly divided along the maritime-mainland bifurcation.[30] ASEAN’s reluctance to raise its stakes in tackling the Mekong challenge will further deepen this fault line in both geography and geopolitics. While the geography of Southeast Asia and its inherent diversity may be structural, ASEAN’s unity and relevance are also a function of agency. For its centrality to Southeast Asia and to the lives of the people inhabiting across the region, ASEAN should raise its stakes in the Mekong. To do that, its member states must, first of all, overcome the sub-regional mentality and embrace the region in its totality.

ISEAS Perspective 2021/69, 19 May 2021


[1] CGIAR – Research Program on Water, Land and Ecosystems, “Mekong River Basin”, https://wle-mekong.cgiar.org/changes/where-we-work/mekong-river-basin.

[2] Brian Eyler, Last Days of the Mighty Mekong (London: Zed Books, 2019).

[3] Basic Framework of ASEAN- Mekong Basin Development Cooperation, Kuala Lumpur, 17 June 1996, https://www.asean.org/storage/images/2013/economic/mbdc/basic%20framework%20of%20ambdc.pdf.

[4] Sree Kumar and Sharon Siddique, Southeast Asia: The Diversity of Dilemma (Singapore: Select Publishing 2008), p. 39.

[5] The Mekong issues refer to a host of intertwined environmental, ecological, developmental and strategic challenges facing the Mekong riparian states. 

[6] Hoang Thi Ha, “Flying the ASEAN Flag in a Pandemic Year: Vietnam’s 2020 Chairmanship”, ISEAS Perspective 2020, No. 137 (3 December 2020), /wp-content/uploads/2020/11/ISEAS_Perspective_2020_137.pdf.

[7] Author Hoang Thi Ha’s interviews with ASEAN member states’ officials 2020.

[8] Brian Eyler, op. cit.

[9] Stefan Lovgren, “Mekong River at its lowest in 100 years, threatening food supply”, National Geographic, 31 July 20219, https://www.nationalgeographic.com/environment/article/mekong-river-lowest-levels-100-years-food-shortages.

[10] Sao Da, “Water volume in Tonle Sap Lake at dangerous levels”, Khmer Times, 21 August 2020,  https://www.khmertimeskh.com/50755781/water-volume-in-tonle-sap-lake-at-dangerous-levels.

[11] “Cambodia’s Tonle Sap shows what’s at stake in the Mekong’s dam-fueled decline”, ASEAN Today, 28 December 2020, https://www.aseantoday.com/2020/12/cambodias-tonle-sap-shows-whats-at-stake-in-the-mekongs-dam-fueled-decline.

[12] “Waning fish-catch in Cambodia’s Tonle Sap region”, The Star, 8 April 2021,  https://www.thestar.com.my/aseanplus/aseanplus-news/2021/04/08/waning-fish-catch-in-cambodia039s-tonle-sap-region.

[13] “Đợt hạn, mặn nghiêm trọng nhất trong lịch sử ĐBSCL”, Nhân Dân Điện tử, 20 June 2020, https://nhandan.com.vn/chuyen-lam-an/dot-han-man-nghiem-trong-nhat-trong-lich-su-dbscl-475180.

[14] Hiebert, M., “Upstream Dams Threaten the Economy and the Security of the Mekong Region”, ISEAS Perspective 2021, No 34 (22 March 2021), /wp-content/uploads/2021/02/ISEAS_Perspective_2021_34.pdf.

[15] Cosslett, Tuyet L., Cosslett, Patrick D., Water Resources and Food Security in the Vietnam Mekong Delta (London: Springer, 2014), p. xiv.

[16] Seah, S. et al., The State of Southeast Asia: 2021 (Singapore: ISEAS – Yusof Ishak Institute), /wp-content/uploads/2021/01/The-State-of-SEA-2021-v2.pdf.

[17] Mely Caballero-Anthony, Paul Teng, Goh Tian, Maxim Shrestha, Jonatan Lassa, “Linking Climate Change Adaptation and Food Security in ASEAN”, ERIA Discussion Paper Series, 2015, https://www.eria.org/ERIA-DP-2015-74.pdf.

[18] Muhamad Varkkey, H., “Addressing Transboundary Haze Through ASEAN: Singapore’s Normative Constraints”, Journal of International Studies, [S.l.], v. 7, pp. 92, (Jan 2011); Nguitragool, P., Environmental cooperation in Southeast Asia: ASEAN’s regime for transboundary haze pollution (New York: Routledge, 2011), p. 58-59.

[19] Heilmann, D., “After Indonesia’s Ratification: The ASEAN Agreement on Transboundary Haze Pollution and its Effectiveness As a Regional Environmental Governance Tool”, Journal of Current Southeast Asian Affairs, 34, 3, p. 101, (2015), https://journals.sagepub.com/doi/pdf/10.1177/186810341503400304.

[20] ASEAN Agreement on Transboundary Haze Pollution, https://haze.asean.org/asean-agreement-on-transboundary-haze-pollution.

[21] Paruedee Nguitragool, Environmental cooperation in Southeast Asia : ASEAN’s regime for transboundary haze pollution (Routledge, 2011), p. 66.

[22] Muhamad Varkkey, op. cit.

[23] Heilmann, op. cit.

[24] Michael Leifer, Selected Works on Southeast Asia, compiled and edited by Chin Kin Wah and Leo Suryadinata, (Singapore: Institute of Southeast Asian Studies, 2005), p. 97.

[25] https://asean.org/asean-socio-cultural/cop-to-aathp-conference-of-the-parties-to-the-asean-agreement-on-transboundary-haze-pollution.

[26] Basist, A. and Williams, C. (2020); Monitoring the Quantity of Water Flowing Through the Mekong Basin Through Natural (Unimpeded) Conditions, Sustainable Infrastructure Partnership, Bangkok, https://data.opendevelopmentmekong.net/dataset/monitoring-the-quantity-of-water-flowing-through-the-upper-mekong-basin-under-natural-unimpeded-con/resource/8433a305-8c7a-49d0-af8b-8778ec289b46.

[27] The Mekong River Commission, Understanding the Mekong River’s hydrological conditions, 2020, https://www.mrcmekong.org/assets/Publications/Understanding-Mekong-River-hydrological-conditions_2020.pdf.

[28] Vientiane Declaration of the Third Mekong-Lancang Cooperation (MLC) Leaders’ Meeting, Xinhuanet, 24 August 2020, http://www.xinhuanet.com/english/2020-08/24/c_139314536.htm.

[29] Bilahari Kausikan, “Why Asean should treat the Mekong like the South China Sea”, South China Morning Post, 17 July 2020, https://www.scmp.com/week-asia/opinion/article/3093546/why-asean-should-treat-mekong-south-china-sea.

[30] Vietnam is the exception because the country has national interests at stake in both the South China Sea (maritime) and the Mekong river (mainland).

ISEAS Perspective is published electronically by: ISEAS – Yusof Ishak Institute   30 Heng Mui Keng Terrace Singapore 119614 Main Tel: (65) 6778 0955 Main Fax: (65) 6778 1735   Get Involved with ISEAS. Please click here: /supportISEAS – Yusof Ishak Institute accepts no responsibility for facts presented and views expressed.   Responsibility rests exclusively with the individual author or authors. No part of this publication may be reproduced in any form without permission.  
© Copyright is held by the author or authors of each article.
Editorial Chairman: Choi Shing Kwok  
Editorial Advisor: Tan Chin Tiong  
Managing Editor: Ooi Kee Beng  
Editors: William Choong, Malcolm Cook, Lee Poh Onn, and Ng Kah Meng  
Comments are welcome and may be sent to the author(s).

Download PDF Version