The Lieutenant River is a 3.7 miles (6 km) tidal river located in Old Lyme, Connecticut

Old Lyme, Connecticut

Old Lyme is a town in New London County, Connecticut, United States. The Main Street of the town is a historic district. The town has long been a popular summer resort and artists' colony...

. It joins the Connecticut River

Connecticut River

The Connecticut River is the largest and longest river in New England, and also an American Heritage River. It flows roughly south, starting from the Fourth Connecticut Lake in New Hampshire. After flowing through the remaining Connecticut Lakes and Lake Francis, it defines the border between the...

 in the estuary

Estuary

An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

, just above the point where that river flows into Long Island Sound

Long Island Sound

Long Island Sound is an estuary of the Atlantic Ocean, located in the United States between Connecticut to the north and Long Island, New York to the south. The mouth of the Connecticut River at Old Saybrook, Connecticut, empties into the sound. On its western end the sound is bounded by the Bronx...

.

The river has a popular public boat launch and is a popular fishing spot.

The Lieutenant River is probably most notable for its continuing popularity among artists and photographers. A number of noted American impressionist

American Impressionism

Impressionism, a style of painting characterized by loose brushwork and vivid colors, was practiced widely among American artists in the late 19th and early 20th centuries.-An emerging artistic style from Paris:...

 artists, including Childe Hassam

Childe Hassam

Frederick Childe Hassam was a prolific American Impressionist painter, noted for his urban and coastal scenes. Along with Mary Cassatt and John Henry Twachtman, Hassam was instrumental in promulgating Impressionism to American collectors, dealers, and museums...

, painted views of the river while staying at the Florence Griswold House in Old Lyme.

The Florence Griswold Museum was designed with windows that have sweeping views of the Lieutenant River.