ORS § 357.271
The board, by resolution duly adopted, may establish sinking funds for the purpose of defraying the costs of acquiring land for library sites, and for acquiring or constructing buildings or facilities. A sinking fund may be created through the inclusion annually within the tax budget of the district of items representing the yearly installments to be credited to the fund. The amount of these items shall be collected and credited to the proper fund in the same manner in which taxes levied or revenues derived for other purposes for the district are collected and credited. The balances to the credit of the funds need not be taken into consideration or deducted from budget estimates by the levying authority in preparing the annual budget of the district. None of the moneys in sinking funds shall be diverted or transferred to other funds, but if unexpended balances remain after disbursement of the funds for the purpose for which they were created, such balances, upon approval by resolution of the board, shall be transferred to the operation and maintenance fund of the district.
ORS 357.271