Questions: 24. The presence of high levels of fecal coliform bacteria in a water source indicates that the water (A) is safe to drink (B) is safe to swim in (C) contains too little oxygen to support fish life (D) has been recently chlorinated at a sewage treatment plant (E) has been contaminated by untreated human or animal waste

The answer is (E): has been contaminated by untreated human or animal waste.

Explanation for each option:

(A) is safe to drink - Incorrect. High levels of fecal coliform bacteria indicate potential contamination by fecal matter, making the water unsafe to drink without treatment.

(B) is safe to swim in - Incorrect. Water with high levels of fecal coliform bacteria is not safe for swimming, as it may contain pathogens that can cause illness.

(C) contains too little oxygen to support fish life - Incorrect. Fecal coliform bacteria levels do not directly indicate oxygen levels in the water. Low oxygen levels are typically measured by other means, such as dissolved oxygen tests.

(D) has been recently chlorinated at a sewage treatment plant - Incorrect. Chlorination is a process used to kill bacteria, including fecal coliforms. High levels of these bacteria would suggest inadequate or absent chlorination.

(E) has been contaminated by untreated human or animal waste - Correct. Fecal coliform bacteria are found in the intestines of warm-blooded animals, and their presence in water indicates contamination by fecal matter, often from untreated human or animal waste.