Which of the following is an indicator of potential sewage contamination in water?

The presence of coliform bacteria is a well-established indicator of potential sewage contamination in water. Coliforms are a group of bacteria commonly found in the intestines of warm-blooded animals, and their presence in water indicates that fecal contamination may also be present. This is critical because pathogens that can cause diseases are often found in the same environments as coliform bacteria. Monitoring for coliforms is a standard practice in water quality assessments to ensure public health safety, especially in drinking water sources and recreational waters.

While high dissolved oxygen levels can indicate a healthy aquatic environment, they do not specifically signify contamination. High nutrient concentrations might suggest runoff or pollution but do not solely indicate sewage contamination, as they can arise from other sources like agricultural fertilizers. Low pH values could indicate acidic pollution but are not directly tied to sewage contamination either. Therefore, the presence of coliform bacteria is uniquely pertinent to assessing the risk of sewage-related health hazards in water bodies.