Officials are monitoring the ocean off Grays Harbor after reports of a large dock drifting off the coast. It's possible the object is among the 5 million tons of debris that washed into the Pacific Ocean after the 2011 tsunami in Japan.

Officials are monitoring the ocean off Grays Harbor after reports of a large dock drifting about 16 nautical miles offshore.

The dock was spotted Friday by fishermen aboard the vessel Lady Nancy, but it has not been seen since. The Quinault Indian Nation has joined federal and state officials in monitoring the ocean and the coastline while the National Oceanic and Atmospheric Administration crunches data to determine the object’s likely trajectory.

Officials said the object appeared to be similar to a dock that beached in Oregon in July. It’s possible the object is among the 5 million tons of debris that washed into the Pacific Ocean after the 2011 tsunami in Japan.

The government of Japan estimated that most of the debris sank quickly, but about 1.5 million tons was dispersed across the north Pacific Ocean.

NOAA said it has received approximately 1,432 reports of debris. Of those, 17 have involved debris from the tsunami. For more information, visit http://marinedebris.noaa.gov/tsunamidebris and http://marinedebris.wa.gov.