The declaration means residents in those counties are being asked to voluntarily cut back their water use by 5 percent.
Boonsboro lifted its ban on outdoor water use Thursday after the reservoir returned to normal levels, thanks to cooperative citizens and repaired leaks in Boonsboro and Keedysville pipes, Boonsboro Mayor Charles Kauffman said.
"But we're still stressing that these are drought conditions and ask people to use their water wisely," he said.
Officials in Smithsburg and Myersville said Thursday they are waiting for several days of steady, soaking rain before they can lift their three-week-long water bans on outdoor use.
Because Hauvers Spring in Smithsburg is so low, the town has been getting water from the Hagerstown reservoir, its main water source now, daily since July 2.
Woodsboro officials said they may have to make their voluntary water ban on outdoor use, instituted on July 8, compulsory if dry weather conditions continue.
Emmitsburg, Md., the fourth town to announce a mandatory restriction, notified residents Wednesday and Thursday of an immediate water ban on outdoor activities in the town.
The dry weather there has depleted the normally steady flow of water from the town's Rainbow Lake over a spillway into the stream that feeds its reservoir.
"Now it's at a point where the water is just trickling over," said Doug Wantz, town water superintendent.
Emmitsburg has received 17.41 inches of rainfall so far this year, a significant drop from the 43 inches that had fallen on the town during the same period last year, according to weather observer Lucille Beale.
In Hagerstown, about 17 inches of precipitation has fallen since January, compared to 45.69 inches of rain that fell on the city through last July, said Greg Keefer, Hagerstown weather observer.
The National Weather Service predicted temperatures in the mid- to upper 90s today with the heat index - the combination of temperature and humidity - reaching 100 to 105. There is a slight chance of an afternoon or evening thunderstorm, the weather service said.
Some relief may be in sight, however. A cold front pushing eastward is expected to drop temperatures to the mid-60s tonight. Highs around 90 are forecast for Saturday and in the 80s on Sunday. The weather service's extended forecast, however, calls for no additional rain until Tuesday.