Dark times for Puerto Rico. 

The task of restoring electricity to the island in the wake of Hurricane Maria will demand an investment of hundreds of millions of dollars, a senior US Army Corps of Engineers official told EFE here Tuesday.

The island faces "a grave situation," Jose Sanchez said in an interview, noting that the powerful Category 4 storm damaged 80 percent of Puerto Rico's infrastructure.

Nearly a month after the hurricane struck on Sept. 20, state-owned utility AEE is generating less than 18 percent of its pre-Maria output.

The Puerto Rico Chamber of Commerce warned weeks ago that many small and medium-sized businesses may go under if the pace of power restoration does not increase, raising the prospect of more pain for an economy that has been in recession for a decade.

And Gov. Ricardo Rossello has said repeatedly that a protracted period of diminished economic activity due to the lack of electricity is likely to spur an increase in the number of Puerto Ricans - who are US citizens - relocating to the mainland United States.

The US commonwealth has lost 10 percent of its population since 2007.

In the days after Maria slammed into Puerto Rico, AEE chief Ricardo Ramos suggested that some areas of the island could wait as long as nine months to get their power back.

"We are working hard," Sanchez said Tuesday, referring to the efforts of his team and AEE's roughly 1,000 employees.

He said that it was impossible to give a date certain for full restoration of electricity due to the many variables at play.

Asked about Rossello's recent statement that nearly 90 percent of AEE customers would have power by mid-December, Sanchez said only that the governor had established "a very aggressive goal."

Explaining the scale of the challenge, Sanchez said that 200 transmission towers and as many as 50,000 electric poles were down, while 10,000 kilometers (6,000 miles) of lines require repair or replacement.

"There are logistics problems in getting equipment and specialists" to the places where they are needed, Sanchez said.

The Army Corps of Engineers awarded the Fluor Corporation a $240 million contract to help rebuild AEE's transmission and distribution system, while Ramon Rosario, the chief spokesman for the Rossello administration, announced Tuesday that the government signed a $4.7 million accord with General Electric for repairs to the Palo Seco power plant near San Juan.