After adopting a resolution stating the facts constituting an emergency by a four-fifths vote of the board at any regular or special meeting, the board may appropriate and make the expenditure necessary to meet an emergency in any of the following cases:

1. (a) Upon the happening of an emergency caused by war, fire, failure or the imminent failure of a water system or supply, flood, explosion, storm, earthquake, epidemic, riot, or insurrection.
2. (b) For the immediate preservation of order or of public health.
3. (c) For the restoration to a condition of usefulness of any public property, the usefulness of which has been destroyed by accident.
4. (d) For the relief of a stricken community overtaken by calamity.
5. (e) For the settlement of approved claims for personal injuries or property damages, exclusive of claims arising from the operation of any public utilities owned by the county.
6. (f) To meet mandatory expenditures required by law.