Coal Run is a tributary of North Branch Buffalo Creek in Union County, Pennsylvania, in the United States.

It flows southeast for several tenths of a mile before entering West Buffalo Township.

Immediately upon entering that township, the stream turns east-southeast for several tenths of a mile, receiving one unnamed tributary from the left.

The stream then flows east-northeast for several tenths of a mile until it reaches its confluence with North Branch Buffalo Creek.

[1] Coal Run joins North Branch Buffalo Creek 0.46 miles (0.74 km) upstream of its mouth.

In 2000, row crops and streambank erosion were the largest contributors of sediment, contributing 289,101 and 230,144 pounds (131,134 and 104,392 kg), respectively.

[4] Coal Run was entered into the Geographic Names Information System on August 2, 1979.

[7] Wild trout naturally reproduce in Coal Run from its headwaters downstream to its mouth.

[8] Vegetated buffer strips occur along 3.3 miles (5.3 km) of streams in the watershed of Coal Run.

The largest contributors of pathogens are urban areas and farm animals (6.526 × 1015 and 5.503 × 1014 organisms per month, respectively).