Wolf Run is a tributary of North Branch Mehoopany Creek in Bradford County and Sullivan County, in Pennsylvania, in the United States. It is approximately long and flows through Wilmot Township in Bradford County and Colley Township in Sullivan County. The stream's watershed has an area of , most of which is agricultural land and woodlots. In a 2001 study, seven species of fish were found in Wolf Run, but no gamefish. More recently, wild trout have been observed as well.
Wolf Run begins in a shallow valley near a wetland in Wilmot Township, Bradford County. It flows south-southeast for a few tenths of a mile before entering an unnamed lake. From the southern outlet of this lake, the stream flows south-southeast for more than a mile before entering Colley Township, Sullivan County, where it receives an unnamed tributary from the . It then turns south-southwest for about a mile before crossing Pennsylvania Route 87 and reaching its confluence with North Branch Mehoopany Creek.
Wolf Run joins North Branch Mehoopany Creek upstream of its mouth.
Wolf Run is not designated as an impaired waterbody.
In 2001, the pH of Wolf Run upstream of its mouth was measured to be 7.2, while the alkalinity was . The water hardness of the stream was and the specific conductance was 60 umhos. When the ambient air temperature was , the water temperature was measured to be .
The elevation near the mouth of Wolf Run is above sea level. The elevation near the stream's source is above sea level.
Wolf Run is a low-gradient stream, falling at a rate of . The stream is wide at a point upstream of its mouth. It flows in a generally southerly direction.
A mountain known as Tyler Mountain is located just to the east of Wolf Run.
The watershed of Wolf Run has an area of . The stream is entirely within the United States Geological Survey quadrangle of Colley. It joins North Branch Mehoopany Creek at Colley.
The main land uses in the watershed of Wolf Run are agricultural land and woodlots. A total of 18 percent of the stream's length is within of a road, while 75 percent is within of a road and 98 percent is within of one. In 2000, the population density of the stream's watershed was , making it the most densely populated watershed of any named tributary of North Branch Mehoopany Creek.
Wolf Run was entered into the Geographic Names Information System on August 2, 1979. Its identifier in the Geographic Names Information System is 1191677.
A concrete tee beam bridge carrying Pennsylvania Route 87 over Wolf Run was built in Sullivan County east of Colley in 1934. This bridge is long and has an average daily traffic rate of 657 vehicles as of November 2014.
In 2001, Pennsylvania Fish and Boat Commission biologists visited Wolf Run and performed a fish sampling, among other research. The stream was found to be too warm for wild trout and too narrow to qualify for the statewide trout stocking program.
Wild trout naturally reproduce in Wolf Run from its headwaters downstream to its mouth. The stream is classified as a Coldwater Fishery.
However, in a 2001 study, no game fish were observed in Wolf Run, though seven other fish species were found. These species include central stoneroller, common shiner, blacknose dace, creek chub, white sucker, pumpkinseed, and tessellated darter.