Woodcliff Lake is a borough in Bergen County, New Jersey, United States. As of the 2010 Census, the borough's population was 5,730, reflecting a decline of 15 from the 5,745 counted in the 2000 Census, which had in turn increased by 442 from the 5,303 counted in the 1990 Census. Most of the borough mandates a minimum lot size of 22,500 square feet for single-family homes, with portions on the borough's east zoned for 15,000 square feet and portions of the borough's northwest and southwest zoned for 30,000 square feet lots.
Woodcliff Lake is also the name of the reservoir that lies primarily within the borough, with a small portion at the southeastern edge located in neighboring Hillsdale.