New York — New York City faces the worst water shortage since a 1960s drought that turned green parks into barren plots and forced 7 million residents to drink and wash less. Officials blame lack of rainfall, increased water use, and nearly nonexistent conservation steps for the current problem. A drought has not been declared formally, but concerned officials note that water levels in 18 upstate reservoirs average 36.9 percent, compared with 90 percent last year. In 1963, the height of a seven-year water crisis, levels dipped to 25 percent. The city, which uses 1.5 billion gallons of water a day, estimates it has about 110 days' worth in its reservoirs.