The board may adopt ordinances for the purpose of regulating, conserving, managing, and controlling the use and extraction of groundwater within the territory of the district. All ordinances shall be adopted, after noticed public hearings by a majority vote of the board. Notice of the adoption of all ordinances shall be given. The ordinances of the district shall become effective on the 31st day after adoption except that the board may, by the vote of at least seven members of the board, dispense with notice of public hearing and adopt an emergency ordinance that shall become effective immediately upon adoption, if the board determines that the public health, safety, or welfare so requires.