City can clean streams if owners don't

Upon the failure, neglect, or refusal of any owner or agent so notified to complete maintenance and clearing of any stream; and to remove any debris, vegetation, silt, or other material from such stream within 30 days after notice has been given as provided for in § 40-2.12 , or within 30 days after the date of mailing of such notice or when service of notice cannot be made, provided that the same was properly addressed to the last known address, of such owner or agent, the chief engineer is authorized and empowered to pay for such maintenance and clearing and removal of debris and vegetation out of city funds or to order the same to be done by city employees or by contract. The chief engineer or authorized employees of the department, including any contractor or the contractor’s agent with whom the chief engineer contracts under this section, are authorized to enter upon the property for the purposes of maintenance and clearing of such streams and the removal of any debris or vegetation described in the notice. Before work is commenced by the chief engineer or authorized employees of the department, or contractor, any owner may perform the necessary maintenance and clearing of the stream and the removal of debris or vegetation at the owner’s own expense.