WASHINGTON — Jack Evans was a summer intern here in 1976, the year Metro, the capital region’s subway system, opened to rave reviews. It was an architectural triumph, with escalators that plunged into clean, well-lit stations — a mass transit marvel “like ‘The Jetsons,’ ” he says — a far cry from the graffiti-scarred, decrepit system of that era in New York.

Now Mr. Evans, 62, is the chairman of the transit agency that oversees Metro — perhaps the city’s least enviable job. Last week, at a conference examining Metro on its 40th birthday, he said out loud what Washingtonians had known for years: The capital’s once-glorious subway system, the nation’s second busiest, is short on cash and a terrible mess.

“It’s a system that’s maybe safe, somewhat unreliable, and that is being complained about by everybody,” declared Mr. Evans, who estimates that Metro could face a $100 million budget shortfall next fiscal year.

Then he dropped a bombshell. He warned that whole lines may have to be closed for months for repairs, adding, “If we do nothing, 10 years from now the system won’t be running.”