It is unlawful to plant willow (salix species), poplar (populus species), cottonwood (populus species) or any other tree or any shrub whose roots are likely to obstruct public or private sewers within 30 feet of any public sewer. The public works director is authorized to remove any trees or shrubs from any public street, or the roots of any trees or shrubs which extend from any public street, when the trees or roots thereof are obstructing, or when the director shall determine that they are liable to obstruct public or private sewers; provided, however, that the director shall give 10 days’ notice in writing to the owner or occupant of the abutting property to remove the same. If such owner or occupant fails or refuses to do so, the reasonable cost of such removal when done by the city shall be a lien upon the abutting property from which such trees or shrubs are removed. The city attorney is authorized, empowered and directed to collect such charge by suit maintained in the name of the city as plaintiff, in any court of competent jurisdiction. (Ord. 1634 § 1, 1996).