Some wikipedia text until I write a new description:

Onalaska is a city in La Crosse County, Wisconsin, United States and a part of the La Crosse, Wisconsin Metropolitan Statistical Area. The population was 16,186 at the 2006 census. The city borders three unincorporated rural towns including: Onalaska, Medary, and Hamilton.

The original village (now city) was platted by Thomas G. Rowe (New York) and John C. Laird (Pennsylvania) in 1851. In its early days, lumbering and related industries served as a basis for its economy.[1]

The City of Onalaska is primarily built on a slightly elevated ridge above the Black River. Natural areas include river bottomland as well as high, heavily wooded, scenic bluffs. It is known as "The Sunfish Capital of the World." A manmade reservoir at the city's western edge is known as Lake Onalaska.