A penalty of five percent shall attach to and become a part of all assessments for local improvements or installments thereof, immediately upon the same becoming delinquent. All such assessments and installments thereof shall become delinquent if not paid prior to the expiration of thirty days from the date of the first publication of the treasurer’s notice upon any such assessment or installment. Any assessment or unpaid balance thereof payable by the mode of immediate payment shall, from and after the date of such delinquency, bear interest at the rate of eight percent per annum until paid.

The city treasurer shall give notice of the time of payment of each installment upon any assessment payable by mode of payment by bonds. (Prior code § 13.48.120.)