Editing Chesapeake Bay (section)

===Hydrology===
[[File:Sunset - Eastern Bay 5.jpg|thumb|View of the eastern bay in Maryland at sunset]]
[[File:Annapolis, Maryland, Usa P1010854.jpg|thumb|The [[Chesapeake Bay Bridge]], near Annapolis, Maryland]]
Much of the bay is shallow. At the point where the Susquehanna River flows into the bay, the average depth is {{convert|30|ft|m|0|}}, although this soon diminishes to an average of {{convert|10|ft|m|0}} southeast of the city of [[Havre de Grace, Maryland]], to about {{convert|35|ft|m|0}} just north of Annapolis. On average, the depth of the bay is {{convert|21|ft|m}}, including tributaries;<ref>{{cite web |url=http://www.cbf.org/site/PageServer?pagename=exp_sub_watershed_geography |title=Geography |publisher=Chesapeake Bay Foundation |access-date=2008-04-21 |url-status=dead |archive-url=https://web.archive.org/web/20071014181514/http://www.cbf.org/site/PageServer?pagename=exp_sub_watershed_geography |archive-date=October 14, 2007 }} Other sources give values of 25 feet (e.g. {{cite web |url=http://www.msa.md.gov/msa/speccol/sc2200/sc2269/html/chartfront.html |title=Charting the Chesapeake 1590–1990 |publisher=Maryland State Archives |access-date=2008-04-21 |archive-date=2021-02-15 |archive-url=https://web.archive.org/web/20210215094045/https://msa.maryland.gov/msa/speccol/sc2200/sc2269/html/chartfront.html |url-status=dead }}) or {{convert|30|ft|m}} deep ({{cite web |url=http://ian.umces.edu/pdfs/iannewsletter1.pdf |title=Healthy Chesapeake Waterways |publisher=University of Maryland Center for Environmental Science |access-date=2008-04-21 |archive-url=https://web.archive.org/web/20080626004705/http://ian.umces.edu/pdfs/iannewsletter1.pdf |archive-date=2008-06-26 }})</ref> over 24 percent of the bay is less than {{convert|6|ft|m|0|abbr=on}} deep.<ref name="Chesapeake Bay Program: A Watershed Partnership: Facts & Figures">{{cite web |url=http://www.chesapeakebay.net/factsandfigures.aspx?menuitem=14582 |title=Chesapeake Bay Program: A Watershed Partnership: Facts & Figures |publisher=Chesapeake Bay Program Office |date=2010-05-04 |access-date=2010-10-29 |url-status=dead |archive-url=https://web.archive.org/web/20101204081804/http://www.chesapeakebay.net/factsandfigures.aspx?menuitem=14582 |archive-date=2010-12-04 }}</ref>

Because the bay is an estuary, it has fresh water, salt water and [[brackish]] water. Brackish water has three [[salinity]] zones: oligohaline, mesohaline, and [[polyhaline]]. The freshwater zone runs from the mouth of the Susquehanna River to north [[Baltimore]]. The oligohaline zone has very little salt. Salinity varies from 0.5&nbsp;[[Concentration#"Parts-per" notation|ppt]] (parts per thousand) to 10&nbsp;ppt, and freshwater species can survive there. The north end of the oligohaline zone is north Baltimore and the south end is the Chesapeake Bay Bridge. The mesohaline zone has a medium amount of salt and runs from the Bay Bridge to the mouth of the [[Rappahannock River]]. Salinity there ranges from 1.07% to 1.8%. The polyhaline zone is the saltiest zone, and some of the water can be as salty as sea water. It runs from the mouth of the Rappahannock River to the mouth of the bay. The salinity ranges from 1.87% to 3.6%. (3.6% is as salty as the ocean.)<ref>{{cite web |url=https://www.researchgate.net/figure/232679222_fig1_Figure-1-Map-of-Chesapeake-Bay-and-salinity-zones-Salinity-zones-based-on-Chesapeake |title=Figure 1. Map of the Chesapeake Bay and salinity zones. Salinity zones... |website=ResearchGate }}</ref>

The climate of the area surrounding the bay is primarily [[humid subtropical]], with hot, very humid summers and cold to mild winters. Only the area around the mouth of the Susquehanna River is continental in nature, and the mouth of the Susquehanna River and the Susquehanna [[mudflat|flats]] often freeze in winter. It is rare for the surface of the bay to freeze in winter, something that happened most recently in the winter of 1976–77.<ref>{{Cite magazine |magazine=Time |title=The Big Freeze |date=1977-01-31 |url=http://www.time.com/time/magazine/article/0,9171,918620-2,00.html |archive-url=https://web.archive.org/web/20080308235254/http://www.time.com/time/magazine/article/0,9171,918620-2,00.html |url-status=dead |archive-date=March 8, 2008 |access-date=2007-03-19 }}</ref>

The Chesapeake Bay is the end point of over 150 rivers and streams.<ref>{{cite web |title=Facts & Figures |url=https://www.chesapeakebay.net/discover/facts |access-date=18 August 2021 |publisher=Chesapeake Bay Program}}</ref> The largest rivers flowing directly into the bay, in order of discharge,<ref>{{cite journal |last1=Zhang |first1=Qian |last2=Brady |first2=Damien C. |last3=Boynton |first3=Walter R. |last4=Ball |first4=William P. |title=Long-term trends of nutrients and sediment from the nontidal Chesapeake watershed: An assessment of progress by river and season |journal=Journal of the American Water Resources Association |date=2015 |volume=51 |issue=6 |pages=1534–1555 |doi=10.1111/1752-1688.12327|bibcode=2015JAWRA..51.1534Z |s2cid=129432081 }}</ref><ref>{{cite journal |last1=Sprague |first1=Lori A. |last2=Langland |first2=Michael J. |last3=Yochum |first3=Steven E. |last4=Edwards |first4=Robert E. |last5=Blomquist |first5=Joel D. |last6=Phillips |first6=Scott W. |last7=Shenk |first7=Gary W. |last8=Preston |first8=Stephen D. |title=Factors Affecting Nutrient Trends in Major Rivers of the Chesapeake Bay Watershed. Water Resources Investigations Report 00-4218 |date=2000 |url=https://va.water.usgs.gov/online_pubs/WRIR/00-4218.htm}}</ref> are the [[Susquehanna River]], [[Potomac River]], [[James River]], [[Rappahannock River]], [[York River (Virginia)|York River]], [[Patuxent River]], and [[Choptank River]].

For more information on Chesapeake Bay rivers, see the [[List of Chesapeake Bay rivers]].

[[File: Chesapeake Bay from airplane.jpg|thumb|The bay viewed from a plane]]