The Six Mile Creek Watershed is a subwatershed of a larger network, the Cayuga Lake Watershed. Other major subwatersheds in Ithaca include Fall Creek, Cascadilla Creek, and Cayuga Inlet.
The Cayuga Lake watershed is the largest of the Finger Lakes, spanning 785 square miles of agricultural, industrial, residential, and forested land. The lake is fed by a network of 140 streams, and its watershed is home to over 120,000 people. Cayuga Lake is also the longest (38.2 miles long), widest (1.75 miles wide), and one of the deepest (435 feet deep) of the Finger Lakes. Because of Cayuga Lake's size and depth, water that enters the lake takes over a decade to cycle through the lake.