It extends for nearly 20 miles (32 km) along the south side of Ashokan Reservoir in Catskill Park, serving as a southerly alternate route of NY 28 through the area.

The shoreline itself is less than one-half mile (0.80 km) from NY 28A, separated by woods and the New York City Department of Environmental Protection fences.

Olive's town hall and municipal garage are a short distance to the west on Watson Hollow Road, which leads through the mountains to Sundown and ultimately to Sullivan County.

Although NY 213 is an east–west route, it actually heads due south from this junction to the nearby hamlet of Olivebridge on its way to Stone Ridge and High Falls.

[6] Continuing east, NY 28A descends to cross Esopus Creek again before climbing back up to the city's watershed visitor center.

[8] At the spillway's southeastern tip is a junction with Stone Church Road,[6] where the route turns back to the north and reenters the park.

[8] Now in the town of Hurley, NY 28A continues to follow the irregular reservoir shoreline to the northeast, but on an alignment slightly farther inland than before.

The junction is roughly two miles (3.2 km) west of the city of Kingston, where NY 28 connects to U.S. Route 209 and the Interstate 87 portion of the New York State Thruway.

[12] According to a 1909 court order, the roads and bridges would be built and maintained by New York City in perpetuity to ensure that the residents displaced by the new reservoir would not be permanently isolated.

Additionally, one bridge along NY 28A in Traver Hollow was temporarily closed in June 1975 due to safety concerns, a move that ultimately led to a lawsuit between the city and the town of Olive over economic hardship caused by the closure.

[14] As part of the reservoir's construction, a north–south road was built across the water body, linking Olivebridge on the south bank to Shokan on the northern side.

[11] This highway was closed to automotive traffic by New York City in early 2002 following the September 11, 2001 attacks, citing a potential security vulnerability.

[7] However, the route was re-opened for traffic that year, and remained open until March 20, 2003, due to a United States Army Corps of Engineers confidential risk assessment, which suggested that the city should close it again to protect the reservoir spillway from sabotage.