Crooked Creek is a tributary of the Tioga River located entirely in Tioga County, Pennsylvania in the United States.
The source is southwest of the unincorporated village of Little Marsh in Chatham Township at an elevation of . The creek first flows east for , then northeast for . The mouth is at the confluence with the Tioga River, just north of the borough of Tioga, at an elevation of .
The difference in elevation ( divided by the length of the creek of gives the average drop in elevation per unit length of creek or relief ratio of 39.1 ft/mi (7.4 m/km ). The meander ratio is 1.07, so despite its name, the creek is fairly straight in its bed.
The watershed area is , with a population of 4,570 as of 2000. Of that area, are forested, are given to agricultural uses, and is open water. The watershed accounts for 12.2% of Tioga County by area.
Crooked Creek has one major impoundment, the Hammond Reservoir, formed by a dam just before it enters the Tioga River. The lake has a surface area of and is administered by the U.S. Army Corps of Engineers, who built the Hammond Dam from 1973 to 1979. Built together with the adjoining Tioga Dam and Tioga Lake (on the Tioga River), the total project cost $200 million.
The dam projects were initially authorized by the United States Congress in the Flood Control Act of July 3, 1958 (Public Law 85-500). A channel connects the two lakes so that Hammond Lake (which has greater storage capacity) may be used to store excess (flood) water from Tioga Lake.
However, in addition to flood control on the Chemung and North Branch Susquehanna Rivers, the dams are also meant to help decrease the acidity of water in the Tioga River downstream of the dams by with the more neutral waters of Crooked Creek. The Tioga River's acidity is caused by acid mine drainage.
The lakes also offer recreational opportunities, including camping, boating, fishing, swimming, and hiking on area trails.