Answer :
Here is the answer to the given question above. The environmental factors that needed to be investigated before draining the lake are as follows: First, you must consider if there is the presence of living animals in it or around it, because these species or animals are depending on the lake for survival. Since you are draining the lake, you will be altering the natural balance in the environment. Next is, you also have to make sure if there is another available source of water that the city could get water from.