The easiest way to establish the level of pollution in a local stream is to measure the level of

The easiest way to establish the level of pollution in a local stream is to measure the level of oxygen. Oxygen is essential for the survival of aquatic life, and the presence of pollutants in the water can decrease the amount of dissolved oxygen. By measuring the oxygen level, we can determine if the water is polluted or not. If the oxygen level is low, it indicates that there is pollution in the water, and the quality of the water is poor. Carbon (IV) oxide, ammonia, and alkalinity are also important parameters to measure, but they may not provide a clear indication of pollution as their levels can fluctuate due to natural processes.