DATUAK Tumbijo, 68, head of the Nagari Togokoto Cultural Assembly—a group that preserves village customs and traditions—can only taste bile upon surveying Lake Maninjau. This is because the waters of the lake, which covers nearly 10,000 hectares in the district of Maninjau, Agam regency, West Sumatra, are a dark green color.

His memories of a clear lake, where he used to see fish swimming in its depths, are now disturbed by the micr