Sparkill Creek rises along the south border of
Blauvelt State Park on the western flank of Clausland Mountain, part of the
Hudson River Palisades. Coursing south, it enters the hamlets of Blauvelt and Orangeburg, flowing under
NY 303 twice as it winds towards the hamlet of Tappan. Just north of the hamlet of Sparkill, the creek turns to the southwest and passes beneath the
Palisades Interstate Parkway and, again, NY 303. Turning south again, the creek passes through downtown Tappan and crosses the New York border, entering Northvale, New Jersey. The creek abruptly turns to the east in Northvale, flowing a short distance before crossing the state line again and reemerging back into New York. Between Tappan and the hamlet of Palisades, Sparkill Brook joins the Creek from the south as its turns to the northeast and enters the Sparkill Gap, a break in the ridge of the Hudson River Palisades. Passing beneath
US 9W and through the hamlet of Sparkill, the creek is impounded by a small dam forming Moore's Mill Pond. Below this dam it is impounded by a larger dam, forming Ferdon Mill Pond. Downstream of the large dam, part of a former mill complex in Piermont, the creek becomes tidal. This section of the creek was once navigable to commercial vessel traffic from the Hudson River, but it is now blocked by a low, fixed span, the Ferdon Ave Bridge, a quarter mile downstream of the former mill complex. Immediately before the Ferdon Ave Bridge is its predecessor, the
Sparkill Creek Drawbridge, which when operational opened to allow Hudson River vessel traffic to travel upstream. The portion of Sparkill Creek downstream of the Ferdon Ave Bridge is navigable to motorized vessels, and homes along this section of the waterway have docks for their watercraft. NOAA nautical chart #12343 Hudson River to Wappinger Creek covers this section of the creek, and the electronic navigation version of this chart shows the majority of water depths along the waterway to be 0.6 meter, or approximately two feet, with some deeper and shallower spots. The final section of the creek meanders three quarters of a mile through the Piermont Marsh before terminating at the Hudson River just south of Piermont Pier. ==Tributaries and diversions==