Miller Run is a tributary of Limestone Run in Union County, Pennsylvania, in the United States. It is approximately long and flows through East Buffalo Township and Lewisburg. The watershed of the stream has an area of . The stream has no officially named tributaries. It is very small and is not a perennial stream, but is impacted by stormwater flows and also has high concentrations of sediment. The stream's chemical hydrology has been significantly affected by human use. Major rock formations in its watershed include the Bloomsburg Formation, the Keyser-Tonoloway Formation, and the Wills Creek Formation.
Most of the watershed of Miller Run is owned by Bucknell University. A significant fraction of the watershed is on urban land, but there is also some forested land. The stream was being channelized as early as the 1930s. In the 21st century, a number of studies and restoration projects have been done on it. The stream is a Warmwater Fishery and six fish species have been observed within it, though only one is found in its lower reaches. It has a very low concentration of benthic macroinvertebrates.
Course
Miller Run begins at the base of a small hill in East Buffalo Township. It flows north for a short distance before turning north-northeast for several tenths of a mile. In this reach, the stream crosses US Route 15, passes through the Bucknell University campus (where it receives an unnamed tributary from the left), and enters Lewisburg. It then turns north for several hundred feet before reaching its confluence with Limestone Run.
Tributaries
Miller Run has no named tributaries. However, it has a tributary that is unofficially known as North Miller Run. The reach of Miller Run that is upstream of this tributary is sometimes known as South Miller Run.
Hydrology and climate
Miller Run is impacted by stormwater flows and also has high concentrations of sediment. The lower reaches of the stream lack a perennial flow during significant portions of the year, especially during droughts. However, it was historically a perennial stream. Additionally, the stream can experience flash flooding during high flow conditions. The chemical hydrology of the stream has been significantly impacted by human use. One example of this is the fact that ion concentrations in the stream are considerably higher than ion concentrations in other similarly sized streams.
The average discharge of Miller Run averages approximately , but can be considerably higher, sometimes over . The stream exhibits highly unusual hydrologic behavior during rainstorms and snowmelts. In typical streams the discharge in the upper reaches peaks before that of the lower reaches. However, in Miller Run, this pattern is reversed and the discharge sometimes even peaks more than once. This is caused by large amounts of water flowing into it from storm drains and runoff-impervious surfaces.
Miller Run has sediment loads as high as 2287 parts per million. This is more than ten times higher than the nearby Buffalo Creek, which is itself "notorious" for its sedimentation. The concentration of dissolved oxygen in Miller Run was once measured to range from over 9 to more than 11 milligrams per liter. The concentration of ammonium in the stream was less than ten milligrams per liter in both its upper reaches and its lower reaches in February 2009 and the nitrate concentration was 1.9 milligrams per liter in its upper reaches and 1.98 milligrams per liter in its lower reaches. The phosphorus concentration was less than 0.1 milligrams per liter in both reaches. The sulfate concentration was 34 milligrams per liter in the stream's upper reaches and 48 milligrams per liter in the lower reaches. The chloride concentration was 81.7 milligrams per liter in the upper reaches and 47.9 milligrams per liter in the lower reaches.