In each reclamation district in Nebraska, the Auditor of Public Accounts shall cause the books of account kept by the board of directors of such districts to be examined and audited. Such audits shall show (1) the gross income from all sources of the district for the year previous; (2) the gross amount of electrical energy supplied by said district; (3) the amount expended during the previous year for maintenance; (4) the amount expended during the previous year for plant investments; (5) the amount of depreciation of the plant during the previous year; (6) the cost of supplying electrical energy, including production cost, transmission cost and distribution cost; (7) the number of employees as of December 31 of each year; (8) the salaries and expenses paid employees and directors; and (9) all other facts necessary to give an accurate and comprehensive view of the cost of maintaining and operating the plant as well as the district.