Harnessing the energy of the St. Paul River in Liberia, the Mount Coffee hydroelectric plant was supposed to bring power — and prosperity — to a country upended by nearly two decades of civil war.

That was before the outbreak of Ebola ravaged the developing nation, where less than 1 percent of the population has access to reliable public electricity. Construction on the plant has ground to a halt. The foreign staffers leading the project have left the country. Hopes of lighting up Liberia by 2016 could are dimming.

The Ebola epidemic has killed more than 2,300 people in Liberia, making it ground zero in the deadly disease’s march across West Africa. But the tragedy encompasses not only those who lost their lives and their families, but also the dreams of a country that was on the cusp on an economic resurgence. With critical public works projects in limbo and businesses struggling, the virus is threatening Liberia’s chance to escape generations of poverty and join Africa’s rising prosperity.

As the worst Ebola outbreak in history unfolds in West Africa, The Post’s Joel Achenbach explains how the deadly virus wreaks havoc on the human body. (Davin Coburn/The Washington Post)

“Liberia was moving,” said Estrada Bernard, chairman of the International Bank in Liberia and the Liberian president’s brother-in-law. “The whole thing hinges upon how well we can get this virus under control.”

The best-case scenario compiled by the World Bank predicts Liberia’s economic growth will still plunge by more than half this year. Rubber, one of the nation’s biggest exports, is expected to fall 20 percent this year. Gold and diamond mining have also dropped off. Beer production plunged 30 percent during the first quarter. The World Bank’s doomsday forecasts total a whopping $33 billion for the entire West African region over the next two years if the virus spreads unchecked.

“The take-away messages from this analysis are that the economic impacts are already very serious in the core three countries … and could become catastrophic ,” the World Bank stated.

It is a sharp break from recent history. Over the past decade, Liberia has emerged as an African success story. Two generations of despotic dictatorship had shrunk the population and decimated public infrastructure. The election of current President Ellen Johnson Sirleaf in 2005 marked a new era of political stability and rapid rebuilding. From roads to rubber farms to five-star resorts — everything seemed to be under construction, creating new jobs and enticing foreign investors into the country.

The renaissance was not just happening in Liberia. Across Africa, the political strife and horrific violence that once defined the continent have abated. In its place is a youthful demographic hungry for work and eager for the trappings of a better life, from cell phones to alcoholic spirits. Africa is now one of the fastest-growing economies in the world, and Liberia was hoping to ride that tide to the next rung in the global ladder.

BET founder Robert Johnson opened the doors in 2009 to a luxury resort on 13 acres of oceanfront property. Just a few months ago, the hotel was touting its Sunday brunch of spare ribs, jollof rice and frosting cake. Spirits giant Diageo was looking to Liberia as not only a manufacturer, but also a market for Guinness.

The country even held its first marathon in 2011. “The one word which best describes Liberia and the Liberia Marathon is: POTENTIAL,” the race Web site proclaims.

The 26.2-mile course this year was supposed to begin at the Eternal Love Winning Africa Hospital in Monrovia, now at the heart of the Ebola outbreak. Instead of athletes, the hospital was housing an isolation unit for those infected with the virus this summer. Weekly marathon training runs were canceled in August, and the race has been rescheduled until next year. The Facebook page now advises runners to “stay safe and take precautions!”

Liberia’s largest employers remain in the country, though many have scaled back operations. Palm oil producer Sime Darby, for example, has replaced plans for a new $10 million plant that can process 60 tons of oil an hour with a more modest five-ton “mini mill” that can be installed within the next eight months.

The company said its roughly 3,000 employees are still receiving pay and benefits, and it is operating a clinic to treat employees and residents who live near the sprawling plantation. A coalition of about 60 foreign companies in Liberia has formed to tackle the disease, work with international aid organizations and commit to the country for the long haul.

“Ebola exposed the fragility of the health system of the countries affected by the virus. It has also tested the governments of these countries, and their international partners,” a company spokesperson said in an e-mail. “Nevertheless, the investment potential is still there. … We are not discouraged by this temporary setback. Our investment is long-term so we are certain we’ll be able to catch up.”

Sime Darby has been in Liberia since 1977, and though it suspended operations during the height of the country’s civil wars, it always reopened for business. But no one is sure how new investors will react, particularly those outside of the mining and agricultural sectors that have long dominated the country’s economy.

The so-called “fear factor” could chill activity not just in Liberia, but spread across West Africa and even spill over into countries that Ebola has not touched. Nearly $53 billion in foreign investment flowed into Africa last year, according to consulting firm Ernst & Young, up 13 percent from 2012.

But one of the biggest obstacles to attracting even more business is perception.

“What I fear most is the impact of panic, which will be interpreted by businesses and investors as if we don’t know what to do,” Donald Kaberuka, president of the African Development Bank Group, said in an interview. “That cannot be the new narrative of Africa.”

Cultivating new industries is critical for Liberia’s development. Nearby Nigeria is a prime example: Income has more than quadrupled over the past decade, according to the World Bank. Telecom companies are erecting cell towers. Internet start-ups modeled after Amazon offer doorstop delivery of Dell laptops and Mama Gold Rice. The country is the epicenter of Africa’s film industry.

And when Ebola came to Nigeria over the summer, the country had the resources and infrastructure to contain the disease in a matter of weeks. No new cases have been reported since the end of August, and international health officials are close to declaring Nigeria as “Ebola-free.”

Meanwhile in Liberia, a hotel that the U.S. military has turned into a makeshift lab to test blood samples for Ebola unplugs the private generator it relies on for power every morning to conserve fuel, according to a scientist working there. At night, only a few light bulbs flicker in the hallways, and bats sometimes fly overhead.

In a plea to world leaders in Washington last week, Sirleaf argued that shoring up the power grid and other public projects are as essential for combating the disease as they are for cementing Liberia’s future.

“I thank you even more today as you join us in meeting the challenges of the Ebola crisis, ensuring that our renewed health care system will prevent a recurrence and our economic gains will be restored,” she said.