President Clinton's top Y2K adviser, John Koskinen, called the Navy's conclusions overly cautious, saying study authors assumed that major utilities would fail unless proved otherwise.
The most recent version of the study, updated less than two weeks ago, predicted "probable" or "likely" partial failures in electric utilities that serve nearly 60 of roughly 400 Navy and Marine Corps facilities.
The study predicted "likely" partial electrical failures, for example, at facilities in Orlando, Fla.; Gulfport, Miss.; Fort Lauderdale, Fla.; and nine other small- to mid-size cities.
It also predicted "probable" partial water-system failures in Dallas; Nashville, Tenn.; Houston; Baton Rouge, La.; Montgomery, Ala; Tulsa, Okla.; and 59 other cities.
The study forecast likely partial natural-gas failures in the middle of winter in Albany, N.Y.; Fort Worth, Texas; Pensacola, Fla.; Charleston, S.C.; Columbus, Ohio; and Nashville.
The military report contrasts sharply with predictions from the White House, which weeks ago said in a report that national electrical failures are "highly unlikely." The White House report also said disruptions in water service from the date rollover are "increasingly unlikely."
Koskinen, who vouched for the authenticity of the Navy report, noted that all its worst-case predictions for failures were marked as "interim" or "partial" assessments.
"It's not nearly as interesting as the world coming to an end," said Koskinen. "The way they worked was, until you have information for contingency planning purposes, you ought to assume there was a problem."
The Year 2000 problem occurs because some computer programs, especially older ones, might fail when the date changes to 2000. Because the programs were written to recognize only the last two digits of a year, such programs could read the digits "00" as 1900 instead of 2000, potentially causing problems with financial transactions, airline schedules and electrical grids.
The Navy report was first summarized on an Internet site run by Jim Lord, a Y2K author, who said he obtained it "from a confidential source of the highest reliability and integrity."
"The military has to work from the worst case, but so do we," Lord told The Associated Press on Thursday. "It's reprehensible for them to know this and keep it from us."
Koskinen said the Navy wasn't withholding information from anyone, noting that the continually updated report was available until recently on a Web site maintained by the Defense Department.
"The last people in the world the department is going to keep informatiofrom is their own people," Koskinen said. "In fact, the whole purpose of the exercise is to make sure they can provide appropriate information to servicemen on their bases and their families."
The report was pulled off the Web site two weeks, Koskinen said. Neither he nor Defense Department officials offered any reason why.