(A) For the purposes of these regulations drainage shall be classified as follows:
(1) Surface drainage is runoff of a limited quantity and/or slow rate that it does not cause erosion of a defined channel;
(2) A minor tributary is any drainage channel having a drainage basin of 640 acres (one square mile) or less in area;
(3) A major tributary is any channel having a drainage basin of not less than one square mile or greater than 25 square miles; and/or
(4) A river is any channel having a drainage basin of greater than 25 square miles.
(B) It is intended that responsibility for drainage be allocated as follows, unless otherwise specifically designated;
(1) The developer is responsible for the following:
(a) All surface drainage on the subdivision or planned unit development;
(b) All increases in surface drainage outside the subdivision which results from the development of the subdivision;
(c) The improvement of all minor tributaries lying within the subdivision or planned unit development;
(d) Any significant increase in rate or quantity of runoff in any minor or major tributary or river which results from the development of the subdivision; and/or
(e) Provision for the maintenance of all floodway and flood-fringe areas of major tributaries and rivers which have not been dedicated to the public.
(2) The city and other levels of government will be responsible for the following:
(a) The improvement of floodways of major tributaries;
(b) The improvement of river floodways; and/or
(c) The maintenance of floodway and flood-fringe areas dedicated to the public.
(`90 Code, § 16-14)