Editing Merrimack River (section)

===History of pollution===

Since 1951, the Merrimack River has seen many alterations and pollutants. It was [[dam]]med and [[canal]]led, as well as used as a dumping spot for [[industrial waste]]. The Merrimack was essential for textile mill complexes, which used the river for discharge from their factories. Citizens recall that the river had unusual colors, smells, and vegetation as a result of the pollution from textile mills and other human-related waste.<ref>{{Cite web |title=Reinventing a River |url=https://www.americanheritage.com/reinventing-river |access-date=March 19, 2023 |website=American Heritage |language=en}}</ref> In the 1960s, the Merrimack River was one of the ten [[List of most-polluted rivers|most polluted waterways]] in the United States due to years of unmediated dumping of raw [[sewage]], [[paper mill|paper]] and textile mill discharge, and [[tannery]] sludge.<ref name=":1">U.S. Army Corps of Engineers. 2006. ''Merrimack River Watershed Assessment''. Available from: New England District, Manchester, NH.</ref> [[Phthalate]]s, a group of chemicals used in the manufacture of plastics and detrimental to human bodily systems, were identified in high concentrations within the river in 1973.<ref>Hites RA. 1973. "Phthalates in the Charles and the Merrimack Rivers". ''Environmental Health Perspectives'' 3: 17-21.</ref> A 1976 study of the chemical dynamics of the Merrimack River found that at that time, the biggest pollution source was [[road salt]].<ref>Caesar J, Collier R, Edmond J, Frey F, Matisoff G, Ng A, Stallard R. 1976. "Chemical dynamics of a polluted watershed, the Merrimack River in northern New England". ''Environmental Science & Technology'' 10 (7): 697-704.</ref> Although the river underwent significant restoration efforts from the 1970s onwards, a 1997 study found that the river continued to suffer from the long-term effects of pollution.<ref name=":1" /> The study identified that the river had elevated [[bacteria]] counts, low [[Oxygen saturation|dissolved oxygen]], and high [[Nutrient pollution|nutrient levels]]. A few years later, a 2002 statewide water assessment stated that elevated counts of ''[[E. coli]]'' and [[fecal coliform]] contributed to the river's largest cause of water quality violations. By the 2000s, the largest pollution concern was [[combined sewer overflow]]. Wildlife has been impacted through the contamination of [[shellfish]]ing beds as well as habitat contamination, and aquatic life has been affected due to excess [[lead]], [[zinc]], and other metals in the river. In addition, human recreational activities such as [[swimming]] and [[boating]] have been restricted in certain areas of the river due to high contamination levels.<ref name=":1" />