Seawater Quality in Mertasari and Serangan Beaches Requires Serious Attention: Findings of Coliform and pH Imbalance

Denpasar, June 2025 — Yayasan Westerlaken Alliance Indonesia has been conducting regular monitoring of seawater quality at two coastal locations in southern Bali: Mertasari Beach and Serangan, throughout the period of January to May 2025. The monitoring aims to assess the physical and microbiological conditions of the coastal waters, which are crucial for environmental health and public safety.

Laboratory test results revealed that several parameters did not meet the seawater quality standards for marine tourism, as stipulated in the Decree of the Minister of Environment No. 51 of 2004.

In several locations, the pH level was found outside the acceptable range (6.5–8.5). For instance, in February, the pH at Serangan Beach was recorded at 8.9, indicating a more alkaline condition. This imbalance has the potential to disrupt marine ecosystem stability. While seawater temperature and clarity remained relatively stable and within acceptable limits, salinity levels in some months also showed slight deviations from the standard, potentially affecting marine life habitats.

Yayasan Westerlaken Alliance Indonesia urges increased environmental monitoring and education for coastal communities. Collaboration among government agencies, local communities, and non-profit organizations is essential to:

• Reduce the discharge of household waste into the sea

• Raise public awareness about the importance of protecting seawater quality

• Promote community involvement in participatory environmental monitoring

“Seawater is a vital asset for Bali—not only for its ecosystems but also for the economy and public health. If water quality continues to decline, the consequences could be widespread—from decreasing populations of marine mammals in Bali to health threats for fishermen and coastal residents,” said Drh. Abdul Latif, Marine Program Coordinator at Westerlaken Alliance Indonesia Foundation.

Yayasan Westerlaken Alliance Indonesia will continue periodic monitoring as a preventive effort to ensure the sustainability of Bali’s marine environment.