| Big Run | |
| Source1 Location: | valley in Penn Township, Lycoming County, Pennsylvania |
| Mouth Location: | Little Muncy Creek in Franklin Township, Lycoming County, Pennsylvania near Lairdsville |
| Mouth Coordinates: | 41.2319°N -76.6092°W |
| Progression: | Little Muncy Creek → Muncy Creek → West Branch Susquehanna River → Susquehanna River → Chesapeake Bay |
| Length: | 4.3miles |
| Source1 Elevation: | 1170feet |
| Mouth Elevation: | 735feet |
| Basin Size: | 3.99sqmi |
| Tributaries Left: | four unnamed tributaries |
| Tributaries Right: | two unnamed tributaries |
Big Run is a tributary of Little Muncy Creek in Lycoming County, Pennsylvania, in the United States. It is approximately 4.3miles long and flows through Penn Township and Franklin Township. The watershed of the stream has an area of 3.99sqmi. The stream is impaired by a high total concentration of nitrogen. A number of bridges have been constructed across it.
Big Run begins in a valley in Penn Township. It flows southwest for a few tenths of a mile before turning west for a few tenths of a mile. The stream then turns south-southwest. After several tenths of a mile, it receives an unnamed tributary from the right and turns south-southwest for a few miles. In this reach, it receives one unnamed tributary from the left and one from the right before entering Franklin Township, where it receives three more unnamed tributaries from the left. The stream's valley then widens before the stream reaches the end of the valley, crosses Pennsylvania Route 118, and reaches its confluence with Little Muncy Creek.
Big Run joins Little Muncy Creek 14.22miles upstream of its mouth.
Big Run is classified as impaired due to high total nitrogen levels. It is a United States Department of Agriculture-Natural Resources Conservation Service priority watershed, as well as a United States Environmental Protection Agency priority agricultural steam.
The elevation near the mouth of Big Run is 735feet above sea level. The elevation of the stream's source is 1170feet above sea level.
The surficial geology along the valley floor in parts of the middle or upper reaches of Big Run mostly consists of alluvium, which contains stratified sand and gravel. However, there are patches of Wisconsinan Till, Wisconsinan and Illinoian Lag, Illinoian Till, and Illinoian Lag nearby, and the valley sides have surficial geology of bedrock consisting of sandstone and shale in some reaches.
During the Wisconsinan Glaciation, the ice profile in the valley of Big Run was 640ft/mi in the last 0.5miles before the terminus. The maximum extent of the ice during the Wisconsinan Glaciation crossed Big Run's course.
The watershed of Big Run has an area of 3.99sqmi. The mouth of the stream is in the United States Geological Survey quadrangle of Lairdsville. However, its source is in the quadrangle of Sonestown. The stream also passes through the quadrangle of Picture Rocks. The mouth of the stream is located within 1miles of Lairdsville.
The hydrologic unit code of the watershed of Big Run is 020502060702. A pipeline crosses the stream at one point.
Big Run was entered into the Geographic Names Information System on August 2, 1979. Its identifier in the Geographic Names Information System is 1192138.
A concrete stringer/multi-beam or girder bridge carrying State Route 2015 over Big Run was built 1miles north of Lairdsville in 1929 and is 32.2feet long. A concrete tee beam bridge carrying a township road and Pennsylvania Route 118 over the stream was built in Lairdsville in 1937 and is 33.1feet long.
In January 2011, Chief Gathering LLC., a subsidiary of Chief Oil & Gas, received a $34,000 fine from the Pennsylvania Department of Environmental Protection for discharging approximately 25200gal of hydrostatic testing water into the watershed of Big Run during a pipeline testing project in August 2010 in Penn Township.