SDCL § 31-12-15: Written contract--Performance bond.

When any bid, as provided for in § 31-12-14 has been accepted, the board of county commissioners, county highway board, or board of township supervisors, as the case may be, shall enter into a contract with the person whose bid has been accepted. The contract shall be in writing specifying the work to be done or the materials to be furnished, or both, the time for completion, and the contract price or rate of payments. The board shall require the person receiving the contract to furnish a bond with approved sureties, and in an amount the board considers sufficient, conditioned upon the faithful performance of the contract according to the plans and specifications.