Tennessee Wastewater Operator Practice Exam

According to EPA recommendations, the average E. Coli concentration in recreational waters should be kept below:

1. 100 CFU/100 ml

2. 200 CFU/100 ml

3. 126 CFU/100 ml

4. 50 CFU/100 ml

The correct answer is: 126 CFU/100 ml

The correct answer reflects the EPA's guideline for the acceptable level of E. coli in recreational waters, which is set to safeguard public health. Specifically, the EPA recommends that the geometric mean concentration of E. coli should not exceed 126 CFU (Colony Forming Units) per 100 milliliters of water over a 30-day period, or when assessing water quality, no more than 10% of samples can exceed 235 CFU/100 ml. This standard is designed to minimize the risk of gastrointestinal illnesses in individuals who may come into contact with, or ingest, the water during recreational activities such as swimming, boating, and other water sports. Keeping E. coli levels at or below this threshold is essential for ensuring that recreational waters are safe for public use and reducing the incidence of waterborne diseases. The other values listed represent levels that are either less conservative for protecting human health or not aligned with the established EPA criteria. Understanding these standards is crucial for wastewater operators to effectively monitor and manage water quality, ensuring compliance with environmental regulations and protecting community health.