Okla. Stat. tit. 82 § 642
All conservancy assessments as provided for in this title, together with all costs in collecting the same, remaining unpaid after they become due and collectable, shall constitute a lien on the specific properties against which the said assessments have been levied, said lien to be coequal with the lien of ad valorem taxes and all other taxes and all special assessments and shall be prior and superior to all other liens upon all the lands and other property against which such assessments shall be levied as is provided in this title. Such assessments shall be collected in each county by the county treasurer of each county as and at the time ad valorem taxes are collected, and any tax sale shall include all charges, and such lien may be evidenced by any ad valorem tax sale certificate including said charge substantially in the form required by law.
If any assessment made pursuant to the provisions of this title shall prove invalid, the board of directors shall subsequently amend all acts or proceedings promptly, and without delay remedy all defects or irregularities as the case may require by making and providing for the collection of new assessments or otherwise.
Unless expressly declared to the contrary, no warranty deed or other deed made pursuant to a judicial sale shall warrant against any portion of any assessment or assessments levied hereunder except installments due before the date of such deed.
Okla. Stat. tit. 82, § 642