The board, in addition to the amount allocated to a project to cover the actual cost of construction, may allocate to the project constructed by it, under contract or otherwise, such amounts as may be determined by it for investigating, engineering, inspection, and other expenses, and may provide for the repayment of the same out of the first money repayable from the project under the contract for its construction, and such money so repaid shall be accounted for within the Water Resources Construction Fund, to be used by the board for the purpose of making investigations for the development of the water resources of the state.