Catawissa Creek (colloquially known as The Cat[2]) is a 41.8-mile-long (67.3 km)[3] tributary of the Susquehanna River in east-central Pennsylvania in the United States.

Coal mining was once a major industry in the Catawissa Creek watershed, but this is no longer the case.

[2] Where the Audenried Tunnel meets Catawissa Creek, the concentration of iron is 0.7 milligrams per liter (mg/L).

[5] At the Green Mountain Tunnel, the concentration of iron is 0.44 mg/L, which equates to a load of 5.3 lb (2.4 kg) per day.

[5] Where Catawissa Creek meets the Susquehanna River, the concentration of iron in the water is 0.11 mg/L, which equates to a load of 82.2 lb (37.3 kg) per day.

[5] Despite the presence of acid mine drainage in Catawissa Creek, its waters are largely clear.

[5] South of Mainville, the Catawissa Creek river valley is made of red shale.

There is also conglomerate, greenish-gray sandstone, olive-colored shale, and anthracite coal near Catawissa Creek.

[9][10] The geological features near the headwaters of Catawissa Creek primarily include anthracite and ridges of sandstone.

[11] At the location where Catawissa Creek flows past Nescopeck Mountain in Main Township, there is a 580 feet (180 m) layer of rock known as the Pocono Formation.

Usually, cultivated Leck Kill soils are topped with an 8-inch (200 mm) thick layer of dark brown silt loam, with a subsoil of reddish-brown silt loam that extends to a depth of 32 inches (810 mm).

This type of soil is topped by a 7-inch (180 mm) thick layer of reddish-brown gravelly silt loam.

[13] Upon entering Schuylkill County in East Union Township, Catawissa Creek flows approximately west-southwest into a valley.

[15] Upon entering North Union Township, Catawissa Creek flows northwards until it reaches the community of Zion Grove, where it takes a sharp turn northwest.

At Zion Grove, the walls of the creek's valley again become considerably higher and steeper.

Catawissa Creek takes a sharp turn to the west and flows under Red Ridge.

It picks up Crooked Run at the edge of North Union Township, and then flows into Columbia County.

It meanders past Dry Ridge and then Full Mill Hill, where Pennsylvania Route 339 crosses it again.

The creek makes a hairpin turn northwards and picks up Gap Run before exiting Beaver Township.

[20] According to legend, Catawissa Creek got its name because an Indian killed a deer near there "in the season when the animal fattens".

[23] In the late 19th century a dam was built on Catawissa Creek in Beaver Township.

[24] From the middle of the 19th century until the early part of the 1970s, coal was mined in the eastern portion of the Catawissa Creek watershed.

Several surveys of Catawissa Creek have been performed by the Pennsylvania Fish and Boat Commission.

Audenried Tunnel drains the Jeansville Coal Basin on the eastern edge of the watershed.

The Audenried Tunnel is responsible for 80% of the acid mine drainage flowing into Catawissa Creek.

As of 2003, Catawissa Creek is considered to be a cold-water fishery between its headwaters and its confluence with Rattling Run.

Large numbers of Amphinmeura and Leuctra have also been observed on the creek between its headwaters and the Audenried and Green Mountain tunnels.

[38] Rattling Run, a 2.3 miles (3.7 km) tributary, also flows into Catawissa Creek from the south near Brandonville.

Dark Run is close to four miles long and flows into Catawissa Creek from the southwest.

There is a larger rapid downstream of a low dam in the lower reaches of the creek.