For six years government workers and volunteers have been collecting the junk that drifts onto the reefs and beaches of Kure and Midway atolls and storing it in a pile on the tarmac at Midway.

The mountain of marine debris grew to an estimated 100,000 pounds.

Now, thanks to a multi-agency state and federal effort, that mountain of rubbish was removed from the tiny Northwestern Hawaiian Islands outpost and shipped to Honolulu.

The charter vessel Kahana arrived here last week carrying 12 shipping containers filled with derelict fishing gear, old nets, faded plastics and lots of other junk.

The haul of marine litter will be processed by Schnitzer Steel Corp. and transported to the city and county’s H-POWER plant, where it will be converted into electricity, officials said Thursday.

“It’s a great cooperative effort,” said David Swatland, deputy superintendent of the Papahanaumokuakea Marine National Monument.

Each year the U.S. Fish and Wildlife Service, the state of Hawaii and the National Oceanic and Atmospheric Administration staff members and volunteers scoop up tons of marine debris from the various islands and reefs that make up the vast national monument.

Over the past 20 years, NOAA staff members and partners have removed more than 1.9 million pounds from the Northwestern islands, according to the monument. In recent years, the agency has sent annual missions to the northwest to search out the marine debris and bring it back to Honolulu.

This time, the haul is made up of marine debris collected by various agency staffers from the shores and reefs of Kure Atoll State Wildlife Sanctuary, Midway Atoll National Wildlife Refuge and Battle of Midway National Memorial within the Papahanaumokuakea monument.

Mark Manuel, NOAA Marine Debris Program Pacific Islands regional coordinator, said the Northwestern islands are particularly vulnerable to floating marine junk because of their location near the convergence of a large series of ocean currents that move clockwise and carry rubbish from across the Pacific.

During El Nino years, when global weather patterns change, the convergence of currents moves south, he said, pushing the debris toward the archipelago, where the islands and reefs act like a comb filtering out the floating material.

Manuel said staff members have noticed an increase in the number of derelict nets in the last six months or so.

“It’s an interesting coincidence directly following (the 2015-16) El Nino year,” he said.

Cleaning up the shores is important, officials said, because wildlife, such as the threatened Hawaiian green sea turtles and endangered Hawaiian monk seals, can become lethally entangled or starve after ingesting the debris.

Often at Midway and Kure Atolls, old fishing gear and plastics rest alongside nests on the beach, officials said, and lots of plastic winds up on Midway simply because adult albatrosses feed their chicks plastics floating in the ocean, mistaken for food.

While these plastics break down into smaller pieces, they never really go away — a problem that impacts the entire ocean ecosystem, according to scientists.

“Marine debris are not something you can clean up just once — it takes a sustained effort over time,” U.S. Fish and Wildlife Service Superintendent Matt Brown said in a press release.

There is no dump in the Northwestern islands that can handle the enormous amount of marine debris, so it must be taken off island, Manuel said.

Kevin O’Brien, the project’s leader with NOAA, said hauling away the growing mountain rubbish on Midway became possible after the state was able to come up with the money to fund the ship.

The estimated cost for the ship time, loading and unloading is about $225,000, according to Jason Misaki, wildlife manager with the state’s Division of Forestry and Wildlife.

At the H-POWER plant, the marine debris will be incinerated for power. Manuel said that for every 100 tons of marine debris, enough electricity is generated to power 43 homes for an entire year.