RICHLAND, Wash. — Workers at the Hanford Nuclear Reservation are trying to flush and clean contaminated groundwater that runs deep under southeast Washington. The massive plumes of radioactive and toxic chemicals are leftovers from plutonium production during World War II and the Cold War.

Decontaminating all that groundwater is a monumental task.

And it will only get harder over time.

Some of the groundwater pumped up from Hanford near the Columbia River is so contaminated it looks like flat Mountain Dew.

“The water coming into the plant out of some of these wells is green,” said Bill Barette, the Department of Energy’s groundwater operations manager on the Hanford site.

The water he’s treating at a newly operational groundwater treatment plant is filled with a cancer-causing chemical called Hexavalent Chromium. And the plant scrubs it clean.

“And it’s coming out and it’s crystal clear,” Barette said. “And there are undetectable levels of chrome in the water on the way out.”

Once the water goes through the plant it’s pumped back into the ground again. Chromium is already leaching into the Columbia River, but officials say the doses are small compared to the massive flow of the big river.

Across the site in central Hanford, there is another plant that has risen up out of the desert in just over a year. It looks like a giant IKEA store in the middle of sagebrush.

This plant will take out two types of radioactive particles and about a half dozen other toxic chemicals. They will be treated with bacteria.

The water this plant pulls out of the ground is so toxic that it needs a seven-story air scrubber-system to keep workers safe.

“The hardest part with this is that I’m really proud of what we’ve done out here, and few people will be able to see it,” said project manager Delise Paragmann.

Back during World War II and the Cold War, the government discharged enough toxic chemicals and water into the ground here to raise the overall water table by 75 feet across a four-mile wide area. The contamination problem varies, but it covers 65 square miles of ground water under the site.

Still, the top groundwater expert at the Washington State Department of Ecology is more worried about what’s above the ground water. It’s in the soil but too deep to dig up.

Dibakar Goswami said that waste hasn’t gotten to the groundwater yet, but it could. “Unless you discover the source it will continuously bleed contamination into the ground water,” he said.

Goswami said there are 550,000 curies and 165,000 tons of chemicals and metals in the soil and in the ground water. That’s why the treatment plants are running day and night in a race to clean up some of Hanford’s groundwater legacy before it reaches the Columbia River.