| Lilley Run | |
| Name Other: | Tributary to South Branch French Creek |
| Map Size: | 300 |
| Pushpin Map: | Pennsylvania#USA |
| Pushpin Map Size: | 300 |
| Pushpin Map Caption: | Location of Lilley Run mouth |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | Pennsylvania |
| Subdivision Type3: | Counties |
| Subdivision Name3: | Erie Crawford |
| Length: | 3.66miles[1] |
| Discharge1 Location: | South Branch French Creek |
| Discharge1 Avg: | 9.73cuft/s at mouth with South Branch French Creek[2] |
| Source1: | divide between Lilley Run and Stranahan Run |
| Source1 Location: | pond about 1 mile west-southwest of Concord Corners, Pennsylvania[3] |
| Source1 Coordinates: | 41.8486°N -79.7294°W[4] |
| Source1 Elevation: | 1652feet |
| Mouth: | South Branch French Creek |
| Mouth Location: | about 0.5 miles west of Concord, Pennsylvania |
| Mouth Coordinates: | 41.8906°N -79.7422°W |
| Mouth Elevation: | 1342feet |
| Progression: | South Branch French Creek → French Creek → Allegheny River → Ohio River → Mississippi River → Gulf of Mexico |
| River System: | Allegheny River |
| Tributaries Left: | unnamed tributaries |
| Tributaries Right: | unnamed tributaries |
| Bridges: | Concord Road, Ormsbee Road, Mitchell Road |
Lilley Run is a 3.66miles long 2nd order tributary to South Branch French Creek in Erie County, Pennsylvania.[2]
Lilley Run rises in Sparta Township, Crawford County, Pennsylvania, north of Crawford County and then flows north into Erie County through Concord Township where it meets South Branch French Creek.
Lilley Run drains of Erie Drift Plain (glacial geology). The watershed receives an average of 46.8 in/year of precipitation and has a wetness index of 453.45.[2]