The land area embraced in any watershed management authority must encompass at least 50 square miles, must be contiguous and must lie within a defined watershed. The area may include lands within any soil and water conservation district. Such authorities may embrace lands lying in one or more soil and water conservation districts. Two or more watersheds may be included in a watershed management authority. Provided, however, no land may be included in more than one watershed management authority and provided further, that no lands or facilities which are subject to the licensing jurisdiction of the Federal Energy Regulatory Commission or the jurisdiction of the Alabama Public Service Commission to issue certificates of convenience and necessity shall be subject to the exercise of any powers or authorities granted herein.