Okla. Stat. tit. 19 § 881
As soon as any subdistrict sewer line or lines shall have been completed the engineer having charge of the work shall compute the whole cost thereof which shall also include the cost of advertising, appraising, engineering and such other expense necessary or essential or incident to the completion of such work and shall apportion the same against all of the lots or pieces of ground in such district in proportion to the area of the whole subdistrict, exclusive of the public highways, and such officer shall report the same to the board of directors and the said board of directors shall thereupon assess a special tax against each lot or piece of ground within said subdistrict, which assessment so made shall be published in some newspaper of the county of general circulation within said district for two consecutive weeks, during which time said assessments without interest may be paid to the clerk. If at the expiration of such time the amount named in such assessment together with the cost of publication, shall not be paid, then said board of directors shall cause special assessment bonds to be issued against such lots or pieces of ground in said subdistrict, which special assessment bond shall recite the date and fact of the making of such assessment, the amount of the assessment, the description of the property against which the same is made, and that the same will be charged or levied against said property in five equal annual installments with interest thereon at the rate of not to exceed six percent (6%) per annum, each of said installments to become due and payable on the 1st day of September in each year which shall become delinquent if not paid before October 1st in said year and said bonds shall be signed by the director of the board of directors and countersigned by the clerk and delivered to the contractor; provided, that the other expenses incurred by said district in addition to the contract price of the work shall be paid to the district by the contractor in cash and the aggregate amount of such bonds delivered to the contractor shall not exceed his contract price, and the amount of the expenses paid in cash to the district by the contractor; provided, further, that in no case shall said district be empowered to pay any such special bonds from any of the funds of said district, nor shall it be liable for the amount of such bonds, until the amount of said assessment shall be collected from the property described in said bonds. Said bonds shall bear four coupons evidencing respectively the first, second, third and fourth installments due thereon; together with interest on the same and interest on the unmatured installment or installments. The bond shall evidence the fifth payment and interest thereon.
Okla. Stat. tit. 19, § 881