Flash flooding feared in already hurricane-ravaged Puerto Rico

The NWS has put out a flash flood warning for the island Saturday.

— -- Hurricane-ravaged Puerto Rico is expecting heavy rain and flash flooding on Saturday as critical relief efforts continue on the island.

All of the islands were extremely hard hit by Hurricane Maria over a week ago, and all are struggling to recover from the blow.

The rain is typical in the tropics, but due to the hurricane, recovery efforts could be compromised.

Additional heavy rain will cause more stress on dams, more likelihood of river flooding, and more likelihood of street flooding. The Guajataca Dam in Puerto Rico continues to be under risk of failure, which could cause life-threatening flash flooding downstream on the Rio Guajataca.

Recovery efforts continued on Friday in Puerto Rico, which is still largely without power and in short supply of drinking water, medical supplies and food.

There are also 9,000 cargo containers with supplies at a port in San Juan but have yet to be distributed to those in need.

"The whole supply chain of distribution has been interrupted," Jose Ayala, vice president of Crowley Puerto Rico Services, told ABC News. "We need to restore the electricity power, we need to restore our roads, we need to restore communications, we need to start moving the diesel around the island."

ABC News' Morgan Winsor and Daniel Manzo contributed to this report.