The Army laid out a worst-case scenario Thursday for downsizing that includes the removal of nearly 20,000 soldiers and civilian workers on Oahu with an associated loss of $1.4 billion in income over the next six years.

The new Army 2020 Force Structure Realignment report examines environmental impacts at 30 installations that would accompany a drop from about 520,000 soldiers now to "well below 400,000," according to the report.

"Such deep reductions are not envisioned," the Army admits, "but analyzing the potential reductions at each of the 30 locations will provide Army leaders flexibility in making future decisions."

The report represents an extreme case — even if sequestration continues in 2016, the Army would be forced down no lower than 420,000 soldiers — amid political and budgetary uncertainties ahead.

"This environmental analysis is just the very start of the process," said Cathryn Kropp, a spokeswoman for the U.S. Army Environmental Command, based in San Antonio. "There’s a lot more strategic considerations that go into the decision making." 

Approximately 16,000 of the soldier and civilian losses would come from Schofield Barracks, with 3,800 more from Fort Shafter. The total represents 18,119 soldiers and 1,667 civilians at both installations.

The numbers assume the loss of 70 percent of Fort Shafter’s soldiers, two brigade combat teams from Schofield, 60 percent of Schofield’s nonbrigade 

combat team soldiers and 30 percent of U.S. Army Garrison Hawaii’s Army civilian workers.

The environmental analysis does not factor in the importance of Hawaii in the "re-balance" to the Pacific.

The Army’s presence in the Pacific has grown to 106,000 active-duty soldiers from about 90,000 in recent years, officials said in April.

"How we have forces based in the Pacific we see remaining about the same for the next several years," Gen. Vincent K. Brooks, commander of U.S. Army Pacific at Fort Shafter, said at the time.

Brooks also said Hawaii’s active-duty soldier count would remain about where it was.

Still, Charlie Ota, vice president of military affairs for the Chamber of Commerce of Hawaii, said nothing can be taken for granted.

"I think we need to prepare for the possibility of significant cuts," he said.

The new report is the second Army downsizing analysis since 2013. The earlier assessment looked at a reduction in Army end strength to 490,000 from 562,000 soldiers.

In June 2013 the Army announced the inactivation of 10 brigade combat teams, with five scheduled to be inactivated in fiscal 2014 and another five in 2015, according to the new report. No cuts were made in Hawaii.

Since then, however, Defense Department guidance has continued to change amid tightening budgets, with the 2014 Quadrennial Defense Review, a planning road map, calling for the Army to reduce in size further to 440,000 to 450,000 soldiers.

The defense review requires that if sequestration cuts are reimposed in fiscal 2016 and beyond, active-component end strength would need to be reduced to 420,000, the new Army report states.

Army Chief of Staff Gen. Ray Odierno has balked at the Army dropping below about 450,000.

If the active component dips to 420,000, "we lose — that last 30,000 makes a huge difference in capabilities that we have," Odierno said in February.

In 2013 Schofield had a total "working" population of 23,717, consisting of active-duty soldiers and Army civilians, students and trainees, other military services, civilians and contractors, according to the new environmental report.

Of that population, 17,538 were soldiers and Army civilians.

Fort Shafter had a total working population of 11,107 in 2013, the report said. Of that, 7,431 were soldiers and Army civilians.

The Army report can be found at aec.army.mil/Services/Support/NEPA/Documents.aspx.