Marine habitats
Mattole River Estuary 2005.jpg
Estuary of the Mattole River

An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.[1]

Estuaries form a transition zone between river environments and maritime environments. They are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of seawater and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.[2]

Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago.[3] Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays, harbors, lagoons, inlets, or sounds, although some of these water bodies do not strictly meet the above definition of an estuary and may be fully saline.

The banks of many estuaries are amongst the most heavily populated areas of the world, with about 60% of the world's population living along estuaries and the coast.[citation needed] As a result, many estuaries suffer degradation from a variety of factors including: sedimentation from soil erosion from deforestation, overgrazing, and other poor farming practices; overfishing; drainage and filling of wetlands; eutrophication due to excessive nutrients from sewage and animal wastes; pollutants including heavy metals, polychlorinated biphenyls, radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion.[3][4]


River Exe estuary
Estuary mouth located in Darwin, Northern Territory, Australia
A crowded estuary mouth in Paravur near the city of Kollam, India
Estuary mouth
Estuary mouth of the Yachats River in Yachats, Oregon
Amazon estuary

The word "estuary" is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. There have been many definitions proposed to describe an estuary. The most widely accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which sea water is measurably diluted with freshwater derived from land drainage".[1] However, this definition excludes a number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff; however the freshwater inflow may not be perennial, the connection to the sea may be closed for part of the year and tidal influence may be negligible".[3] This broad definition also includes fjords, lagoons, river mouths, and tidal creeks. An estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides. The sea water entering the estuary is diluted by the fresh water flowing from rivers and streams. The pattern of dilution varies between different estuaries and depends on the volume of fresh water, the tidal range, and the extent of evaporation of the water in the estuary.[2]

Other Languages
Адыгэбзэ: Iестуарий
Afrikaans: Estuarium
العربية: مصب
asturianu: Estuariu
Avañe'ẽ: Parapaha
azərbaycanca: Estuari
Bahasa Banjar: Muhara
беларуская: Эстуарый
беларуская (тарашкевіца)‎: Эстуарый
भोजपुरी: नदी मुहाना
български: Естуар
bosanski: Estuarij
català: Estuari
Cebuano: Estuwaryo
čeština: Estuár
Cymraeg: Aber
dansk: Æstuarium
Deutsch: Ästuar
eesti: Estuaar
Ελληνικά: Εκβολή
español: Estuario
Esperanto: Estuaro
euskara: Estuario
فارسی: پای‌رود
français: Estuaire
Frysk: Tijmûning
Gaeilge: Inbhear
Gaelg: Inver
galego: Estuario
客家語/Hak-kâ-ngî: Hò-khiéu-vân
한국어: 삼각강
hrvatski: Estuarij
Bahasa Indonesia: Estuari
íslenska: Árós
italiano: Estuario
עברית: שפך נהר
Jawa: Sungapan
ಕನ್ನಡ: ನದೀಮುಖ
ქართული: ესტუარი
Kreyòl ayisyen: Estyè
Latina: Aestuarium
latviešu: Grīva
lietuvių: Estuarija
македонски: Естуар
മലയാളം: അഴിമുഖം
მარგალური: ესტუარი
Bahasa Melayu: Muara
Nederlands: Estuarium
日本語: 三角江
нохчийн: Эстуари
norsk: Estuar
norsk nynorsk: Estuar
Nouormand: Engoulême
occitan: Estuari
oʻzbekcha/ўзбекча: Estuariy
polski: Estuarium
português: Estuário
română: Estuar
русский: Эстуарий
саха тыла: Эстуарий
Scots: Estuary
shqip: Estuarët
Simple English: Estuary
slovenčina: Estuár
slovenščina: Estuarij
српски / srpski: Естуар
srpskohrvatski / српскохрватски: Estuarij
suomi: Estuaari
svenska: Estuarium
தமிழ்: கயவாய்
татарча/tatarça: Эстуарий
українська: Естуарій
vèneto: Estuario
Tiếng Việt: Cửa sông
walon: Egoloe
Winaray: Estero
ייִדיש: לעפצונג
粵語: 入海口
中文: 河口