A map of the Metrorail system yesterday incorrectly depicted the status of two unbuilt stations. The U Street station on the Green/Yellow Line and the Wheaton station on the Red Line are both included in the 75-mile system that the federal government is currently willing to fund.

Metro, breaking years-old policy, yesterday formally identified which unbuilt segments of the 101-mile Metrorail master plan the federal government is not willing to fund at present.

The Reagan administration has said it is willing to finance only a 75-mile system. Metro General Manager Richard S. Page, briefing a Metro board committee yesterday morning, displayed a map showing four segments that he said lie beyond that range.

The four, the last in line to be built, are: the Green/Yellow Line from U Street to Greenbelt, the Green Line from Anacostia to Rosecroft, the Red Line from Wheaton to Glenmont and the Yellow Line from Franconia-Springfield to just before King Street.

Metro officials said federal officials had given way a little bit, agreeing to include in the fundable segments the Green/Yellow Line from Mount Vernon-UDC to U Street, which would raise the system to just over 76 miles. That segment would serve a densely populated, transit-dependent neighborhood, the type of project to which federal programs give top priority.

Federal grants cover about 80 percent of Metrorail's construction costs. Shortly after taking office, Reagan administration officials announced they would fund only 75 miles until further notice, due to the recession and federal deficits. Money for the remaining 26 miles, officials said, would be considered when the economy had improved.

Metro, feeling that a 101-mile system is crucial to maintaining political unity among its diverse members, refused to publicly acknowledge the 75-mile concept. However, building schedules indicated that the system would reach 75 miles in the late 1980s or early 1990s, when only the four segments Page named today would remain unfinished.

The question was largely academic until this year, when construction schedules called for Metro to apply for the first major grant to start building one of the four, a track project near West Hyattsville.

That money still has not been applied for.

With the question of funding beyond 75 miles becoming more pressing, Page briefed board members yesterday on the impact of the current federal position.

He said that the Urban Mass Transportation Administration, which distributes federal transit aid, had indicated it would fund only purchase of real estate for the remaining lines (the land could be resold and the money recouped if the line was not built) and design work.