Editing Water quality (section)

===Environmental water quality===
{{multiple image
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| image1            = Water cleanliness sign, Dublin.jpg
| caption1          = Sign in [[Sandymount]], Ireland, describing water quality, giving levels of [[Fecal coliform|faecal coliform]] ''[[E. coli]]'' and ''[[Enterococcus faecalis]]''
| image2            = View of urban runoff discharging to coastal waters.jpg
| caption2          = [[Urban runoff]] discharging to coastal waters
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{{See also|Environmental monitoring|Freshwater environmental quality parameters}}

'''Environmental water quality''', also called '''ambient water quality,''' relates to water bodies such as [[lake]]s, [[river]]s, and [[ocean]]s.<ref>{{Cite web |url=https://www.epa.gov/wqs-tech/supplemental-module-human-health-ambient-water-quality-criteria |title=Supplemental Module: Human Health Ambient Water Quality Criteria |date=2022-06-28 |publisher=EPA}}</ref> Water quality standards for surface waters vary significantly due to different environmental conditions, ecosystems, and intended human uses. Toxic substances and high populations of certain [[microorganism]]s can present a health hazard<ref>{{Cite journal |last1=Adlish |first1=John I. |last2=Costa |first2=Davide |last3=Mainardi |first3=Enrico |last4=Neuhold |first4=Piero |last5=Surrente |first5=Riccardo |last6=Tagliapietra |first6=Luca J.|date=2020-10-31|title=Polyethylene Identification in Ocean Water Samples by Means of 50 keV Energy Electron Beam |journal=Instruments |volume=4 |issue=4 |pages=32 |doi=10.3390/instruments4040032 |arxiv=2009.03763 |quote=Plastic is the most common type of marine debris found in oceans, and it is the most widespread problem affecting the marine environment. It also threatens ocean health, food safety and quality, human health, and coastal tourism, and it contributes to climate change |doi-access=free}}</ref> for non-drinking purposes such as irrigation, swimming, fishing, rafting, boating, and industrial uses. These conditions may also affect wildlife, which use the water for drinking or as a habitat. According to the EPA, water quality laws generally specify protection of fisheries and recreational use and require, as a minimum, retention of current quality standards.<ref>{{Cite book |url=https://www.epa.gov/sites/production/files/2014-10/documents/handbook-chapter3.pdf |title=Water Quality Standards Handbook Chapter 3: Water Quality Criteria |publisher=EPA |year=2017 |id=EPA 823-B-17-001}}</ref> In some locations, desired water quality conditions include high [[Oxygen saturation|dissolved oxygen]] concentrations, low [[Chlorophyll a|chlorophyll-a]] concentrations, and high [[water clarity]].<ref name="Tango">{{cite journal | last1=Tango | first1=Peter J. | last2=Batiuk | first2=Richard A. | title=Deriving Chesapeake Bay Water Quality Standards | journal=JAWRA Journal of the American Water Resources Association | publisher=Wiley | volume=49 | issue=5 | date=2013-09-04 | issn=1093-474X | doi=10.1111/jawr.12108 | pages=1007–1024| bibcode=2013JAWRA..49.1007T | s2cid=102492027 }}</ref> 

There is some desire among the public to return water bodies to pristine, or pre-industrial conditions.<ref>{{Cite web |url=https://www.fs.usda.gov/restoration/Watershed_Restoration/ |title=Watershed Restoration Program |publisher=US Forest Service |location=Washington, DC |access-date=2022-10-05}}</ref> Most current environmental laws focus on the designation of particular uses of a water body. In some countries these designations allow for some [[water contamination]] as long as the particular type of contamination is not harmful to the designated uses. Given the landscape changes (e.g., [[land development]], [[urbanization]], [[clearcutting]] in forested areas) in the [[drainage basin|watersheds]] of many freshwater bodies, returning to pristine conditions would be a significant challenge. In these cases, environmental scientists focus on achieving goals for maintaining healthy ecosystems and may concentrate on the protection of populations of [[endangered species]] and protecting human health.
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