||This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (May 2010)|
|Location||Cayuga County, New York, USA|
|Lake type||Ground Moraine|
|Catchment area||208 sq mi (541 km²)|
|Basin countries||United States|
|Max. length||11 mi (17 km)|
|Max. width||1.3 mi (1.6 km)|
|Max. depth||177 ft (54 m)|
|Water volume||212,000,000,000 US gal (0.80 km3)|
|Surface elevation||712 ft (217 m)|
|Islands||2 (Off of Burtis Point and Deauville Island)|
Owasco Lake /oʊˈwɑːskoʊ/ is the sixth largest and third easternmost of the Finger Lakes of New York in the United States of America (USA). The name Owasco can be roughly translated from a Mohawk and Iroquois term meaning "crossing".
The lake is eleven miles (17 km) long and the city of Auburn is located at the northern end and takes its drinking water from the lake. The lake lies entirely within the boundaries of Cayuga County. Its width ranges from one half mile (0.8 km) at its southern end to one mile (1.6 km) near the northern tip. Owasco Lake's deepest point is 177 feet (54 m), has a volume of 212 billion US gallons (800,000,000 m3), and has a watershed of 208 square miles (540 km2). Owasco's surface is roughly 712 feet (217 m) above sea level, controlled by a dam on the lake's outlet, located in the city of Auburn.
Located at the south end of the lake is the hamlet of Cascade, which consists of a community of cottages, South Shore Marina, and a restaurant, Cascade Grill.
Owasco Lake is an excellent recreation spot. Because it is smaller and shallower than many other Finger Lakes, its waters warm up much more quickly, so swimming, skiing, and boating are popular. At the lake's northern end is Emerson Park, a county park featuring a beach and boat launch. The lake's northeastern corner is home to the private Owasco Yacht Club, founded in 1889.
In the nineteenth century, Owasco Lake was a popular vacation spot for the well-to-do. A casino located just north of Cascade hosted guests travelling by rail along the western length of the lake. Vestiges of the railway remain in the swampy waters, but the casino burned down in the early years of the twentieth century. The "indianist" composer Arthur Farwell camped on the east shore in 1899, before assuming his teaching duties at Cornell University, and wrote a charming set of piano pieces depicting his experience, entitled "Owasco Memories." He included a representation of "The Casino Across the Lake."
Owasco has a relatively large catchment area, compared to its overall volume. Unlike many of the other Finger Lakes, it is almost completely surrounded by agricultural land so the lake is especially vulnerable to high levels of nitrogen from farm run-off. It is also downstream from the villages of Moravia and Groton. This has created a marked increase in milfoil and other lake weed growth and affected oxygen levels in the lake. Sewage treatment effluent from two communities flows into the lake, which is not monitored with such stringent controls as neighboring Skaneateles Lake, which has the purest water of all the Finger Lakes.
- U.S. Environmental Protection Agency: Owasco Lake 
- Dave Tobin. "A Watertight Watershed." Post-Standard, December 24, 2006