Mad River courses through woodlands in Wolcott during late May.
|Counties||New Haven County|
|Source||Outlet of Cedar Lake|
|- location||Wolcott (though Cedar Lake extends north into Bristol)|
MAD RIVER (CONNECTICUT) Latitude and Longitude:
|Length||11 mi (18 km)|
|Basin size||20.35 sq mi (52.7 km2)|
|- left||Lindsley Brook, Finch Brook|
|- right||Break Hill Brook, Old Tannery Brook|
The Mad River is a river that flows through northern New Haven County, Connecticut in the United States. Rising at the outlet of Cedar Lake just south of Bristol, it courses roughly 11 miles through Wolcott and Waterbury before emptying into the Naugatuck River.
Prior to settlement by the Connecticut Colony, the broad region encompassing the Mad River was a hunting ground frequented by native Algonquian people of the Mattabesec and Tunxis tribes.  The territory was known to these inhabitants as "Mattatuckoke", believed to translate to "place without trees",  and it correlated roughly to what is today referred to as the Central Naugatuck Valley. These lands were purchased and settled by individuals from the Connecticut Colony during the 1670s and 1680s. 
Prior to the industrialization of the Naugatuck Valley, local mills harnessed the waters of the Mad River to produce goods such as flour, cider and saw timber.  The river's economic importance grew enormously as brass manufacturing rose to prominence in the region in the mid-1800s. Several large factories in Waterbury relied upon the Mad River to animate heavy machinery, even though the river's modest watershed was prone to yield insufficient waterflow during dry spells. Consequently, the Mad River and a few of its tributaries were impounded upstream in rural Wolcott, creating a system of reservoirs which could be used to supplement reduced waterflow during seasonal droughts. 
By the late 19th-century, the lower stretches of the Mad River were known to be tremendously polluted by industrial operations. Factory waste, as well as sewage produced by throngs of factory workers, was discharged directly into the river. One observer of the Mad River in 1887 noted that water downstream of Scovill Manufacturing Company, one of the foremost brass producers in Waterbury, "showed extreme contamination; it was of a dark turbid color, with a strong odor and was covered with iridescent films of oily and greasy matters". 
Strengthened environmental regulations in the 1970s forbade the release of toxic chemicals into both Mad River and the nearby Naugatuck River and tightened restrictions on the pollutants billowing from the factory smokestacks. Significant industrial pressure on the Mad River ceased by the 1980s when the brass and copper companies in Waterbury, which had been in decline since World War II, shuttered the last of their major factories. 
Although the federal and state governments do not maintain any parkland on Mad River, some municipal parks are located along the river in Waterbury and Wolcott.
Scovill Reservoir, a 121-acre lake created by impounding the Mad River in central Wolcott, is a recreational reservoir which offers activities including fishing, boating, swimming and hiking.  Wolcott's Peterson Park is situated along Mad River, as well. In fact, the 35-mile CFPA Blue-Blazed Mattatuck Trail begins in the park and follows the Mad River for some time through a woodland setting. 
Further downstream in Waterbury, the 93-acre Hamilton Park encompasses a length of the Mad River and offers swimming, ice skating and hiking (in addition to sports fields that don't directly incorporate the river).  
Free-flowing stretches of the Mad River are not generally believed to be capable of supporting significant populations of riverine gamefish. In 2015, for example, the official Connecticut Angler's Guide neglected to so much as mention the Mad River in its index of rivers and streams.  Dramatic seasonal reductions in waterflow and a shortage of deep pools means that coldwater fish, such as native brook trout, are likely to have considerable difficulty flourishing in the river when water temperatures rise.  Furthermore, dams along the river in both Wolcott and Waterbury obstruct the natural migration of fish.
However, lakes and ponds produced by impounding the Mad River behind dams offer deeper, cooler, larger habitat areas in which fish of numerous species are able to thrive. Scovill Reservoir, which occupies roughly 120 acres along the Mad River in central Wolcott, is known to support trout, largemouth bass, sunfish, yellow perch, chain pickerel and black crappie. As of 2013, the reservoir was designated a "Catfish Lake" and is stocked regularly with channel catfish.  Scovill Reservoir is also known to host a significant population of bowfin, a large "primitive fish" which is common in the Southern United States but very unusual in New England. The fish was illegally introduced to the reservoir in the 1970s and has since become naturalized. 
- Goodman, Florence. "Wolcott Historical Society News - October 2007". Wolcott Historical Society. Wolcott Historical Society. Retrieved 23 January 2016.
- Trumbull, James Hammond (1881). Indian Names of Places, Etc., in and on the Borders of Connecticut: With Interpretations of Some of Them. Hartford: Press of the Case, Lockwood & Brainard Company. p. 27. Retrieved 23 January 2016.
- Goodman, Florence. "Wolcott Historical Society News - September 2011". Wolcott Historical Society. Wolcott Historical Society. Retrieved 23 January 2016.
- Public Documents of the Legislature, Volume 1. Hartford: Connecticut General Assembly. 1888. p. 228.
- Guest, Raechel. "Myriad Of Factors Led To The Collapse Of Brass Production In Waterbury". The Waterbury Observer. The Waterbury Observer. Retrieved 23 January 2016.
- "Recreation - Woodtick Reservoir Information". Town of Wolcott. Town of Wolcott. Retrieved 8 February 2016.
- "Recreation - Peterson Park Information". Town of Wolcott. Town of Wolcott. Retrieved 8 February 2016.
- David F. Ransom (November 1995). "National Register of Historic Places Inventory/Nomination: Hamilton Park" (pdf). National Park Service.
- "Hamilton Park". Waterbury Life. iPage. Retrieved 8 February 2016.
- 2015 Connecticut Angler's Guide (PDF). Connecticut: State of Connecticut Department of Energy & Environmental Protection. 2015. pp. 40–48. Retrieved 10 February 2016.
- Shmukler, Chad. "Trout and Water Temperature: How Hot is Too Hot?". Hatch Magazine. Cignal Media LLC. Retrieved 11 February 2016.
- Leukhardt, Bill (September 17, 1995). "Bowfin: The Ancient, Ugly Side Of Fishing". Hartford Courant. Hartford Courant. Retrieved 11 February 2016.