A wide range of radon content in surface waters was noted incidental to studies of radon in spring and well waters of Hot Springs and Potash Sulphur Springs, Garland County, Arkansas. Subsequently a reconnaissance survey of radioactivity of nearby streams and lakes showed the radon contents of streams range from 0.0084 to 1.07 millimicrocuries per liter of water, and those of lakes range from less than 0.001 to 0.123 millimicrocuries. Streams flowing over Ordovician black shales contained an average of 0.275 millimicrocurie radon per liter of water. Those flowing over black Stanley shale of Mississippian age contained an average of 0.046 millimicrocurie radon per liter of water.The radon content in Potash Sulphur Creek where it flows over the uranium-bearing rocks of the Potash Sulphur Springs syenite complex ranged from 0.09 to 3.16 millimicrocuries per liter of water. Ground water in a drill hole in uranium-bearing rock contained an average of 58.75 millimicrocuries per liter of water. Waters from small springs were shown to lose as much as 41.3 percent of total radon content in the first 4 feet of surface flow below the point of emergence. The methods of radon determination in the field are believed applicable to prospecting for low-grade uraniferous deposits, especially in black shale areas, in areas of heavy overburden, and in areas of saturation by ground water where ordinary detection devices may be somewhat limited.