Tenn. Code § 69-5-209
In establishing any such district, all necessary lands may be appropriated as provided in this chapter, and a right-of-way as much as two hundred feet (200') wide may be so appropriated, if deemed necessary, for the situs and location of any ditch or drain, or for the location of a new route or channel for any natural watercourse for the whole way or parts of the way of its course. The natural bed of any watercourse in such district may, insofar as it may be utilized and necessary, be so appropriated to the end that such bed or channel may be cleaned out, deepened, or widened; but the provision in this section as to the width of such right-of-way shall not prevent the county court from ordering appropriated such other lands as may be deemed necessary for the purposes of such improvement district under this chapter.
T.C.A. § 69-5-209