Neb. Rev. Stat. § 31-230

The city council of a city of the metropolitan class upon receipt of a request pursuant to section 31-229 , may, if it finds that natural flow is being obstructed, cause the natural watercourse to be cleaned out. Except as provided in section 31-221 , the cost thereof may be levied as a special assessment and apportioned among the property owners specially benefited thereby and collected in the same manner as special assessments are levied and collected.