Milling and other industries were drawn to its banks, and it is impounded several times in its lower course, most significantly at Chadwick Lake, the Town of Newburgh's local water supply.

In the wake of successful cleanup efforts, some local citizens and organizations have proposed a system of parks and trails along the lower creek.

[5] The creek rises on the western slope of the long glacial ridge known as Marlboro Mountain, a half-mile east of the small hamlet known as Tuckers Corners in the Ulster County town of Plattekill.

Finally, just north of Newburgh's Town Hall, it crosses 300 again and turns to the east, paralleling Gardnertown Road for almost a mile to county-owned Algonquin Park.

It parallels 17K through a slightly wooded corridor, then is impounded again to create Muchattoes Lake, the center of a housing project built during the city's urban renewal efforts in the early 1970s.

Nothing was done about this until 1984, when Robert F. Kennedy, Jr., sentenced to 1,500 hours of community service with Hudson Riverkeeper after an arrest for heroin possession the year before, heard from the organization's founder, John Cronin, about local complaints about the pollution of Quassaick Creek.

The work with Riverkeeper had led Kennedy to decide on environmental law as a career, and he resolved to identify all the polluters along the creek and sue them.

[10] Kennedy has since cited the experience as an epiphany, the moment he grasped the connection between environmentalism and his family's traditional involvement in social justice: "The battle for the environment ... was the ultimate civil rights and human rights contest, a struggle to maintain public control over publicly owned resources against special interests that would monopolize, segregate and liquidate them for cash.

[12] In December 2023, the organization Riverkeeper was awarded nearly 4 million dollars in federal funding to remove Holden Dam, now failing and obsolete, from Quassaick Creek.