After completion of the hearing required by section 23-2906, the county board, if it determines that formation of the proposed district would promote public health, convenience, or welfare, shall propose such changes in the boundaries of such proposed district or of the areas into which such proposed district is to be divided as it shall deem proper. The county board shall call a special election for the purpose of approval of the formation of such district and the boundaries thereof by a majority of the qualified electors of the area affected by such district, or may submit the question of approval to be voted upon at any primary or general election.