The river starts in the town of Cheshire, flows through Hamden and New Haven, and discharges into New Haven Harboron Long Island Sound. The river’s length is 17.4 miles (28.0 km).

The mill river is rich in cultural and economic history. The Mill River got its name from the Mills that were built on its banks that utilized the running water to power machinery.

A mill for grinding corn was built near East Rock in 1642. This mill was a grist mill and was tremendously important to the economy of the area. By 1780 there were eight mills. In time the river provided power for Eli Whitney’s gun factory, now the Eli Whitney Museum. The many farmers were able to rent time at the mill to grind their grain and sell/use it for their needs.

Other minor mills were also established during the 17 and 18 centuries—a carriage factory, a mill to make carriage wheels and axles, a brass factory, a mill for fulling cloth and a paper mill. Other minor establishments also utilized the river for hydropower.

In 1798, this mill became even more prominent in the areas history when Eli Whitney bought it and the grounds to erect his arms factory.


Whitney increased the height of the dam from 6 feet to about 27 feet in 1860, and 31 feet in 1866. In 1916, it was raised another 19 inches to the current height. The original dam was wooden, but Whitney Sr. and his son Eli Whitney Jr. changed the dam to masonry, with many advancements for increased utility and safety.

For almost 130 years, Lake Whitney provided a sizeable amount of water to the water supply of New Haven County. Some 15 mgd (millions of gallons per day) are safely extractable from the reservoir according to the Regional Water Authority.

From 1860 till 1991, the LakeWhitney created by the dam was used as a public water supply. The Mill River has continued to add to the public water supply even since 1991 due to four wells in Hamden and Cheshire that use the stratified-drift aquifer in the upper Mill River basin .

The upper Mill River is strictly regulated for this reason, and all industry has been removed from the river above the reservoir. Flora and fauna have thrived in this situation, and the water quality has remained pure.

planned highway


In 1942 New Haven city planners first considered locating an arterial road over the Mill River headed through East Rock, and this was “intermittently considered” into the 1950s. In 1959 and 1960, all parties seemed in agreement over the general purpose and location of the connector. But a few years later, the East Rock Connector became a flashpoint in controversy between city officials, residents, and park groups, who called it a waste of good park land, and the state highway department, who called it an integral part of the state highway system.

In the reach south of the tidal gate the river has more evidence of historical industrial use.  Notably, English Station is an abandoned thermal power plant. It occupies eight acres of land on Ball Island in the Mill River. It was constructed from 1924 to 1929.


The plant operated as a coal- and oil-fired power plant for United Illuminating until it stopped electricity-generating operations in 1991.

At many points residents have tired to start a trail along the river. Notably Tom Holahan and friends,  established portions of the trail between Humphrey and Grand.  Evidence of this work can be see seen as benches along the bank of the river.


Source Mill History:

Source East Rock Connector:

Source Eli Whitney Image:




Source: and

Source: Centenary of Hamden, Connecticut: 1886. History of the town of Hamden