Lake Lillinonah /ˌlɪlɪˈnoʊnə/ is a manmade lake located in Fairfield, Litchfield and New Haven counties of Western Connecticut, approximately 60 miles (97 km) northeast of New York City. It is the second largest lake in Connecticut, smaller only than Candlewood Lake. The lake is bordered by six towns: Brookfield, Bridgewater, Newtown, New Milford, Roxbury, and Southbury. It was formed in 1955 by impoundment of the Housatonic River and the Shepaug River by the Shepaug Dam which was built by the Connecticut Light and Power Company. Some of the most expensive real estate in the Greater Danbury area is located on the shores of the lake, in the towns of Brookfield, Bridgewater and Newtown.

The Lake Lillinonah Authority is a governing body responsible for overseeing the lake's management and conservation. Established to address environmental concerns and enforce boater safety rules, the authority collaborates with local governments to maintain the lake's ecological balance and enhance public access.

• www.lakelillinonahauthority.org
• www.friendsofthelake.org