b'INTERNATIONAL WATERSHoWever,rivers in the south, adjacent to the major city centers, remain stressed by municipal, agricultural and industrial pollution sources. These continuous stressors ultimately result in deleterious local events such as harmful algal blooms (HABs), extreme hypoxic or even anoxic water formation, and extensive natural and aquaculture-grown fish kills. One such river, thePa Sak , located within the Chao Phraya River drainage basin, has been most affected by anthropogenic activities over the years, Water Quality Monitoring NetworkInstallations such as these dot theprimarily from municipal and industrial Pak Sak river at regular intervals, keeping a close eye on changes thatwastewater discharge.could impact the rest of the country.Several recent large and high-profile fish kill events (e.g., Trichopodus BURMA Wang trichopterus - an abundant local PingYom Nan LAOS gourami species) have prompted the government to take action, including funding real-time water quality monitoring stations. The Pa Sak Geographically, the Pa Sak Rivers upper PA SAK THAI- reaches originate in the steep mountain forests and streams of the Phetchabun Sakae LAND Mountains of Northern Thailand.KrangChao Phraya Its waters eventually empty into the CHOLASIT DAM Lopburi River system near the ancient capital city of Ayutthaya (north of ThaChin Bangkok), a United Nations Educational, BANGKOK Scientific and Cultural Organization (UNESCO) World Heritage Site, and CAMBODIA then finally into the Chao Phraya basin. The large disparity in rainfall from wet and dry seasons often produces extremes in water level and flow. GULF ofWith superimposed effects of climate THAILAND change that are exacerbating drought and flooding events, farmingpredominantly rice farming and aquacultureare a more riskybusiness for locals.Whos Minding the Planet? 47'