Birchall Falls is a scenic waterfall located on the West Branch of the Beer Kill in the hamlet of Greenfield Park in southern Ulster County, New York. The headwaters of the West Branch of the Beer Kill originate at an unnamed lake in the eastern portion of Sullivan County just east of Woodbourne. The West Branch, measuring approximately 10 miles in length, then flows into Sandburg Creek at Ellenville, which in turn flows northwards to its confluence with the Rondout Creek at Napanoch, which in turn flows northwards to join the Hudson River at Kingston. The West Branch is stocked by the NY Department of Environmental Conservation annually with 1,500 brown trout. Some brook trout may also be found in the headwaters. The east-flowing Beer Kill is named for the yellowish water color that comes from sediments and minerals, giving it a beer-like appearance.