Miss. Code Ann. § 51-29-153

When said board of commissioners of said consolidated district have been appointed and have qualified as required by law, the several boards of commissioners of the said separate drainage districts shall cease to exist, and their power and authority shall terminate. They shall be divested of all of the power and authority theretofore vested in said several boards of commissioners, and all of their said power and authority and jurisdiction in respect to the territory and drainage improvements of their said respective separate districts shall vest in, and thereafter be exercised by, said board of commissioners of said consolidated district.