NY 55A is a loop off of NY 55 at the Rondout Reservoir. It runs along the north side of the reservoir, while NY 55 runs along the south side. NY 55A is also known as BWS Road because it is under the jurisdiction of the Bureau of Water Supply, an agency within the New York City Department of Environmental Protection. It has special reference markers with "NYC" on the first line. New York City is involved here because the reservoir is part of the city's water supply, despite being many miles from the city.