(Portland, OR)  --  Most of the public drinking fountains, known as Benson Bubblers, are being shut down by the Portland Water Bureau during the current cold spell.  Officials tell KOIN-TV that the city experiences about 200 water-main breaks each year, and frozen bubblers can make sidewalks dangerous for pedestrians.  A few of the fountains will remain in operation, including one at 5th Avenue and West Burnside, one on the waterfront near the west end of the Steel Bridge, and another under the Burnside Bridge.  The Water Bureau will turn the bubblers back on after the cold spell passes.