Nothing herein contained shall be construed to forbid or hinder the maintaining and repairing the drawbridge hereinbefore particularly mentioned, or any other bridge erected by public authority, or the making of dams, mounds or tide banks, for the draining of low grounds, and improving of meadows, by the owner or owners of the greater part of the lands, low grounds, or meadows, included within the same dams, mounds or tide banks, anything herein contained to the contrary in any wise notwithstanding.