1.    Upon adoption of a resolution, a county that is not included in any public health unit may request inclusion as a part of an existing health district. Upon receipt of a request to become part of an existing health district, the district board of health shall consider the request and, if the board approves the request by a majority vote, shall submit the matter to each county in the health district. If a majority of the counties approve the request by a majority vote, the requesting county becomes a part of the health district.

2.    Upon expansion of a health district under this section, the number of board of health members must be adjusted to allow the added county the same proportion of members allowed to member cities and counties of the existing health district as determined under this chapter.

3.    Any two or more health districts may merge into a single health district upon a majority vote of the respective boards of health and a majority vote of the governing body of each county. The assets of each merging health district become the property of the newly created health district. Board of health membership of a new health district must be determined under section 23-35-03, unless otherwise decided by the board. The new health district maintains the same authority and powers of the previous health    districts. The mill levy of the newly created health district is not limited by the old mill levy but may not exceed the amount allowed under section 23-35-07, unless one or more of the combining entities was previously levying more than five mills, in which case the mill levy for property within the former entity that was levying more than five mills may not exceed the cap, expressed in mills, as previously authorized for that entity.

4.    Upon adoption of a health district plan by two or more counties, the joint board of county commissioners shall appoint a district board of health.