DMCR warns Cambodia’s dam near Trat coast could affect future maritime boundary

Thailand’s Department of Marine and Coastal Resources (DMCR) said on Tuesday, December 23, 2025 it is concerned that a sediment-retention dam on the Cambodian side near Trat’s coastal border could, in the long term, affect shoreline changes and complicate future maritime boundary delimitation between the two countries.

The DMCR was commenting after reports that Cambodia had agreed to dismantle part of the structure south of Ban Hat Lek in Hat Lek subdistrict, Khlong Yai district, Trat.

Navy raised the issue through border mechanism

The Royal Thai Navy has previously said it raised concerns about the dam with Cambodia via a regional border committee some time ago, and that Cambodia had recently agreed to dismantle it.

However, it is still unclear whether the dam would be fully removed as social media footage showed a bulldozer digging what appeared to be only a small canal through part of the structure to allow seawater to pass.

How the dam could change sediment movement

The DMCR said sediment carried by tides could be trapped by the dam, leading to gradual build-up of land on the Cambodian side.
At the same time, it warned that blocking sediment from naturally replenishing Thailand’s shoreline could accelerate beach loss and coastal erosion on the Thai side.

Environmental and livelihood impacts

The department said disrupted sediment flow could also affect the growth of coastal mangroves, leaving areas denuded.

It added that shrinking beaches and altered shorelines could damage habitats for small marine and coastal species, and could also affect tourism and local fishing grounds used by Thai fishermen.

Why it matters for maritime delimitation

The DMCR warned that if the Cambodian shoreline expands while the Thai shoreline retreats over time, it could affect the reference shoreline used in future maritime boundary and continental shelf discussions—potentially creating overlapping maritime claims.

What happens next

The DMCR said it would continue monitoring the situation and reiterated the need for clear, effective action on the structure to prevent longer-term environmental impacts and potential effects on Thailand’s national interests.