y built his gun factory in 1798 on the Mill River below where the dam is today. It was here that Eli Whitney began the use of the interchangeable parts production process which became known as the American System of Manufacturing. Over the years much interest was given to making East Rock into a public park. Through generous donations of land from Yale College and individual families, East Rock Park went into operation in 1880 as a public park.
The Mill River is one of New Haven’s most beautiful rivers. It is dammed up to form Lake Whitney, a public water supply. The Lake lies in depressions created during the ice age about 10,000-15,000 years ago. The clear water coming out of the Whitney Lake supports fish and invertebrate. While the Quinnipiac tribe lived near the river, they harvested fish, crab, and shellfish from its waters. Fresh water springs ran from the base of East Rock. One hundred years ago the Mill River was a prime spot for swimming, boating, and fishing all the way down the river past Chapel Street . The park where the Mill River joins the Quinnipiac River was a popular sunbathing and swimming area. The Mill River was a tidal river healthy and abundant in wildlife.
Today the rich soil deposits of the river and its flooding and eroding action influence the plant growth in the low flood plain. There is a high water table preventing the deep penetration of root systems and secure anchorage of trees, thus many trees topple alongside the river. The black willow with its shallow, broad root system successfully thrives long the river banks. Other vegetation we find within the low flood plain of the Mill River are Pin Oak, Shrubs; such as Nannyberry and Silky Dogwood. The multiflora rose is a popular habitat and food source for nesting birds. Cattail marshes also provide cover for nesting and migrant birds. These marshes include water atruim, skunk cabbage, and swamps with woody shrubs. A very unusual fern grows in the shallow margins of the water. This unique plant is the water shamrock and looks like a floating four-leaf clover. The plants from Lake Whitney and Bantam Lake are the original stock from which all water shamrocks in the United States originate. Because the Mill River is a tidal river, there is an influx of salt water twice a day with the tidal changes. The seawater on the surface of the river tends to sink as lighter fresh water rises, and mixing takes place from the surface to the bottom of the river. This is known as tidal overmixing. The river water flows seaward on a shallow surface over an upstream movement of seawater. An unusual variety of vegetation grows within the confines of the fresh and salt water mix. We find a salt content in the river up to the footbridge crossing the Mill River. Here we begin to find cattails growing. These plants need less than 10% salt in the water source in order to survive. The plant material needs to be as hardy as the aquatic animal life that thrives in this fresh and salt water mix.
There is more life in a healthy wetland than there is in almost any other kind of habitat. A healthy wetland can support huge numbers of insects, fish, birds, and other animals. East Rock Park is on a major bird migration route bringing over 200 species of birds through, many of which are rarely seen elsewhere in the state. These birds converge on the wetlands on the way to their summer or winter homes to “refuel” on the rich food supply found in marshes. The spring migration of over twenty species of warblers through the park bring bird watchers from all over Connecticut. Throughout the winter, black ducks and pied-billed grebes winter on the river and woodpeckers, chickadees, brown creepers, and nuthatches, to name a few, live among the bare tree trunks.
Wetlands are vital nurseries for many species. Young fish, crab, and other creatures spend their earliest days in wetlands protected before moving out into the open waters. Wetlands also give protection to many endangered species. About 35 percent of all of the animals and plants listed as threatened or endangered in the U.S. e