Complex sentence: This led to perchlorate release into Lake Mead in Nevada and the Colorado River which affected regions of Nevada, California and Arizona, where water from this reservoir is used for consumption, irrigation and recreation for approximate half the population of these states.
Split into simpler sentences: This led to perchlorate release into Lake Mead (in Nevada) and the Colorado River. This affected regions of Nevada, California and Arizona, where water from this reservoir is used for consumption, irrigation and recreation for approximate half the population of these states.