Areas of the western US are looking for sources of additional water to help ease shortages caused by the continuing 4-year drought. Some scientists wondered if thinning the forests to reduce water use might improve water catches into reservoirs and increase water supply.
However, as noted in this blog posting from the Southern Research Center at the USDA Forest Service, research shows that there is a mix of impacts from this. If only a little thinning is done, then the extra amount of water available is not large and thus of limited value. If too much thinning is done, then the chance of floods in an extreme rain storm increases significantly. Other factors which need to be considered are water quality and forest fire threat.
