§ 16-72  DRAINAGE CHANNELS AND STORM SEWERS OUTSIDE ADDITION BOUNDARIES.
   (A)   The city or county reserves the right to require improvements, provisions of drainage easements, and for provision of agreements beyond the boundaries of the subdivision to facilitate flow of water through the addition, to avoid probability of law suits based on damage from changed runoff in the subdivision, and to provide continuous improvements of the overall storm drainage system.
   (B)   Requirements outside the addition may include the following:
      (1)   Improvements may be required in channels or storm sewers flowing to or from the addition, or in channels or storm sewers located in adjacent areas that are affected by flow of water from the addition.
      (2)   The following kinds of improvements may be required:
         (a)   Enlargement or replacement of undersized drainage structures to provide free flow;
         (b)   Removal of obstruction;
         (c)   Straightening of channel;
         (d)   Widening or deepening of the channel;
         (e)   Construction of erosion control structures;
         (f)   Back sloping, sodding and/or rip rapping of bank; and
         (g)   Construction of closed or open paved storm sewers for the purposes of closing gap or continuation of overall storm sewer system.
      (3)   Property owner agreements, where required, shall be designed to protect the city or county from probable law suits for damage, caused by changed runoff condition.
      (4)   When subdivision development will result in increased runoff beyond the boundaries of the subdivision which cannot be accommodated through channel improvements without causing downstream flooding, the Planning Commission may require the construction of one or more retention reservoirs on the subdivision which will temporarily impound and discharge water from the subdivision site at the rate and volume equivalent to the discharge from the undeveloped subdivision or planned unit development site.  The design shall be for a 100-year frequency flood.  Plans shall be approved by the City or County Engineer.  The construction and maintenance of retention reservoirs shall be the responsibility of the developer.
(`90 Code, § 16-18)  (Ord. 2570, passed - -)