Where lands have been heretofore sold at general tax sale for taxes and drainage assessments and the certificate is held by the county, such lands as to drainage assessments thereon shall be certified back to the drainage commissioners upon their demand, together with all penalties and interest accrued thereon, for collection and enforcement of all drainage assessments as provided by this act N.M. Stat. Ann. § 73-7-25 to 73-7-35, but such certificate shall remain intact as to general taxes; and in cases where lands have been sold to the county as above stated, the district may if it desires pay the general taxes with interest and penalties and shall thereupon be entitled to an assignment of the certificate of sale and at the expiration of the time allowed by law for redemption shall be entitled to deed therefor if unredeemed.