Airlines and businesses were baffled by the decision to halt tourism to Boracay, one of the chain of islands known as the Visayas, which was visited by two million tourists previous year and brought in revenue of more than $1 billion.
In February, Mr Duterte said Boracay's water had turned into a "cesspool" with human waste being discharged into the sea.
Officials had warned businesses had been releasing wastewater into the surrounding waters.
This is based on the draft timeline by the inter-agency task force, composed of the DOT, Department of the Interior and Local Government (DILG), and Department of Environment and Natural Resources (DENR).
The government will start by checking which hotels and resorts comply with environmental regulations and then build new sewage lines on the island.
Domestic airlines announced on Thursday they would scale back the number of flights to the jumping-off point for the 1,000 ha island. "Especially since it will only be for six months", added Bello.
Galvez, who led troops in the five-month battle to retake Marawi city from terrorist insurgents that occupied the southern Philippines city in May, will replace Gen. Rey Leonardo who will finish his extended term on April 24, Xinhua reported.
"Whether foreign or local, they will not be allowed to enter the island".
"It's unfair for compliant establishments to be affected by the closure", executive director Pia Miraflores told AFP.
The Boracay Foundation Inc., a business association on the island, had asked the government to shut down only those violating environmental laws.
"The tour guides have already complained that they have no more guests".
On Friday, the country's tourism industry scrambled to manage the fallout from the temporary shutdown of Boracay island, which threw into chaos trips planned by hundreds of thousands of tourists.
"I hope (there will be) no mess and no chaos, " she added.