Sentence:  The department apparently intends to make the Rural Roads Authority a revolving fund under which new <WSD>bonds</WSD> would be issued every time a portion of the old ones are paid off by tax authorities . 
Meaning of the word marked with <WSD> tags:  a certificate of debt (usually interest-bearing or discounted) that is issued by a government or corporation in order to raise money; the issuer is required to pay a fixed sum annually until maturity and then a fixed sum to repay the principal