Bonds or assignable certificates authorized in Section 4-55A-20 N.M. Stat. Ann. for the construction of a street, road, walkway, bridge, overpass, underpass, pathway, alley, curb, gutter or sidewalk project may be purchased by the street and road improvement fund; provided that the bonds or assignable certificates shall be held in trust by the county treasurer and any receipts from the sale of the bonds or assignable certificates or from the payment of the assessment made to pay the interest and principal of the bonds or assignable certificates shall be held in trust by the county treasurer, and any receipts from the sale of the bonds or assignable certificates or from the payment of the assessment made to pay the interest and principal of the bonds or assignable certificates shall be credited to the street and road improvement fund.