A Cleaner Urban Environment is Key to Protecting the Tonle Sap Lake

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Improvements to wastewater, drainage, and solid waste management in cities around the Tonle Sap are crucial in protecting Southeast Asia’s largest freshwater lake from pollution and other threats of urbanization. 

The Tonle Sap basin is home to a third of Cambodia’s 17 million population. As the urban areas around the lake are vital economic centers, the Government of Cambodia introduced key reforms to boost infrastructure development to support their future growth and promote their citizens’ health and well-being. Ultimately, the investments are expected to protect Tonle Sap from pollution and other threats due to unregulated growth.  

Tonle Sap II Project 

The Second Urban Environmental Management in Tonle Sap Basin (Tonle Sap II) project was formulated in line with the government’s sustainable growth and climate-resilient infrastructure development program. Funded by the Asian Development Bank (ADB) and the Government of Cambodia, the $98 million investment aims to improve wastewater, drainage, and solid waste management in the cities of Battambang, Stueng Saen, and Serei Saophaon.  

The interventions will ensure that urban waste and pollution do not adversely impact Tonle Sap’s highly diverse ecosystem, which is critical to Cambodia’s food security, and that the urban areas surrounding the lake can adapt to the growing impacts of climate change.  

Origins of Tonle Sap II and its progress to date

In 2016, CDIA worked with the Ministry of Public Works and Transport (MPWT) and the governments of the three cities to prepare the Tonle Sap II project. They developed a medium-term prioritized investment program, conducted a pre-feasibility study, and developed the preliminary engineering design of the identified priority projects. 

Seven years after the completion of the CDIA-supported study, its monitoring and evaluation team tracked the progress of project implementation. Based on observations and key informant interviews, the team found out that the project was 75% completed. Upon full implementation, it is expected to improve the public’s health and surrounding environment, leading to a better quality of life for the residents living near Tonle Sap and its tributaries. 

In Battambang City, the CDIA team has confirmed that their controlled landfill with a capacity of 313,900 cubic meters (cum) under Phase I has been fully constructed and handed over to the province along with the landfill equipment. Its operation and maintenance (O&M) structure has also been set up and training activities on landfill operations have been provided. Meanwhile, their wastewater treatment plant (WWTP) with 8,500 cum capacity, including pumping stations, and 109 km of separate sewer network was 75% completed and on track to meet the target completion date.  

In Serei Saophoan, the construction of the 97,900 cum-controlled landfill and the 3,500 cum-WWTP facilities, including pumping stations, and 110 km of sewer network is ongoing. 

In Stueng Saen, their 97,900 cum-controlled landfill under Phase I has been completed and turned over to the province along with the landfill equipment. Like Battambang, their O&M structure has also been established just as training on landfill operation was still ongoing. Moreover, their 3,500 cum-WWTP facilities including pumping stations and 54 km of sewer network have been completed.

A total of 2,142 households have been connected to the sewer network, of which 190 are poor.   

Benefits to communities  

The CDIA team had the chance to speak with project beneficiaries who have been connected to the sewer network, and one of them was Mrs. Seng Noa from Sangkat Kampong Ro Tesh, Stueng Saen City who shared her experience before and after project implementation:  

“This is a low-lying area, so flooding was our main problem [before the project]. When the floodwaters seep into our septic tank, it would overflow, causing an unpleasant smell and contamination. Our roads were always flooded, and we would either use a boat or wade through the contaminated floodwaters and mud if we needed to go somewhere.” 

“Now, life is much better. With the new sanitation system, wastewater does not get stuck in our place, so there is no unpleasant smell or flood anymore. Even though I am living alone at the age of 70, I am OK because I no longer have to deal with any sanitation and flooding problems.”

Lessons for cities implementing similar initiatives  

Although project implementation of the Tonle Sap II Project was delayed due to the COVID-19 pandemic, procurement issues, and changes in government priorities, cities wanting to implement similar initiatives can learn from the project preparation experience in terms of the enabling factors that facilitated its implementation.  

These include the alignment and consistency of the infrastructure subprojects with existing national plans; CDIA’s direct engagement with stakeholders during the study; appropriate implementation mechanisms that build on the existing organizational setup of MPWT and the Ministry of Industry, Science, Technology and Innovation (MISTI); and the introduction of several innovations as well as international best practices, such as the installation of separate systems for stormwater and wastewater, and the upgrading of solid waste management from open dumpsite to controlled landfills, among others.  

“Through the CDIA study, other donors became interested in supporting us,” said His Excellency Vong Pisith, Deputy Director General of MPWT. “Our collaboration has helped us improve our project readiness for donor support,” he added.  



A. Project implementation

In Battambang:

  1. Controlled landfill

2. Wastewater facilities

In Stueng Saen:

  1. Controlled landfill

2. Wastewater facilities

B. Interviews with project implementers and beneficiaries

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