§ 80. Three feet depth to be maintained. Whenever a municipal
corporation shall divert or cause to be diverted the water, or a portion
thereof, of a fresh water stream or streams outside the limits of an
incorporated city flowing into a tidewater creek or estuary which
tidewater creek or estuary before such diversion was navigable for
vessels of twenty or more tons burden, it shall be the duty of the
corporation so diverting or causing to be diverted such stream or
streams of fresh water to keep said navigable tidewater creek or estuary
deepened to the depth of at least three feet at low water mark from its
mouth to the head of tidewater for the full natural width of said creek,
and to maintain such navigable depth of water at all times, but in the
county of Nassau it shall not be compulsory to maintain such depth to
any greater width than fifty feet.