Is the hyphen optional?

While that remained the official death toll, Prime Minister Giuseppe Conte said from Genoa that the number would rise. The ANSA news agency reported that it could reach around 35, citing fire brigade sources.

A 50-metre high section of the bridge, including a tower that anchored several stays, crashed down with as many as 35 vehicles driving on it in torrential rain. Huge slabs of reinforced concrete plunged onto two warehouses, train tracks and a riverbed.

Is the hyphen between metre and high optional?

Thanks.