The board of a school district may issue and sell evidences of indebtedness under chapter 21-03 to finance the construction or improvement of a project approved under this chapter. The principal amount of the loan and the evidences of indebtedness to repay the loan may not exceed the lesser of thirty percent of the school district's taxable valuation or five million dollars. Evidences of indebtedness issued under this chapter constitute a general obligation of the school district.