Estuary

{
  "id": "MLC-T-ENV-010126",
  "term": "Estuary",
  "field": "Environment",
  "definition": "1. A complex ecosystem between a river and near-shore ocean waters where fresh and salt water mix. These brackish areas include bays, mouths of rivers, salt marshes, wetlands, and lagoons and are influenced by tides and currents. Estuaries provide valuable habitat for marine animals, birds, and other wildlife.\n\n2. A partially closed coastal body of water where freshwater and saltwater mix.\n\n3. Brackish-water areas influenced by the tides where the mouth of a river meets the sea.\n\n4. A partially enclosed body of water where fresh water from rivers and streams mixes with salt water from the ocean. It is an area of transition from land to sea.\n\n5. Region of interaction between rivers and near-shore ocean waters, where tidal action and river flow create a mix of fresh and salt water; may include bays, mouths of rivers, salt marshes, and lagoons; brackish water ecosystems; may shelter and feed marine.\n\n6. Region of interaction between rivers and near-shore ocean waters, where tidal action and river flow mix fresh and salt water. Such areas include bays, mouths of rivers, salt marshes, and lagoons. These brackish water ecosystems shelter and feed marine life, birds, and wildlife.\n\n7. 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 from land drainage; an inlet of the sea reaching into a river valley as far as the upper limit of tidal rise, usually being divisible into three sectors; (a) a marine or lower estuary, in free connection with the open sea; (b) a middle estuary subject to strong salt and freshwater mixing; and (c) an upper or fluvial estuary, characterized by fresh water but subject to daily tidal action; limits between these sectors are variable, and subject to constant changes in the river discharge.\n\n8. \"Regions of interaction between rivers and nearshore ocean waters, where tidal action and river flow mix fresh and salt water. Such areas include bays, mouths of rivers, salt marshes, and lagoons. These brackish water ecosystems shelter and feed marine life, birds, and wildlife\" (EPA 1992, 11). In EMAP, large estuaries are defined as those estuaries greater than 260 km2 in surface area and with aspect ratios (i.e., length/average width) of less than 20. Large tidal rivers are defined as that portion of the river that is tidally influenced (i.e, detectable tide > 2.5 cm), greater than 260 km2, and with an aspect ratio of greater than 20. Small estuaries and small tidal rivers are those systems whose surface areas fell between 2.6 km2 and 260 km2.\n\n9. A semi-enclosed coastal body of water which has a free connection with the open sea. The seawater is usually measurably diluted with freshwater. (2) The part of the river that is affected by tides. (3) (SMP) The zone or area of water in which freshwater and saltwater mingle and water is usually brackish due to daily mixing and layering of fresh and salt water.\n\n10. A place where fresh and salt water mix, such as a bay, salt marsh, or where a river enters an ocean.\n\n11. Semi-enclosed body of water that has a free connection with open seas and within which the seawater is measurably diluted with fresh water derived from land drainage. The salinity of an estuary exceeds 0.5 parts per thousand (by mass) but is typically less than 30 parts per thousand (by mass).[40 CFR 125.83 (CFR 2013)]\n\n12. Partially enclosed body of water where fresh water from rivers and streams mixes with salt water from the ocean. It is an area of transition from land to sea. [Chesapeake Bay Glossary]\n\n13. Semi-enclosed coastal waters which have a free connection to the territorial sea.\n\n14. The benefits people obtain from ecosystems. These services include the production of food and water; regulating, such as the control of climate and disease; supporting, such as nutrient cycles and crop pollination; and cultural, such as spiritual and recreational benefits.",
  "subject": "Water",
  "references": [
    "Environmental Issues Terms & Acronyms; Pesticides Glossary",
    "Estuaries Glossary",
    "Sediment Total Maximum Daily Loads (TMDLs) Glossary",
    "Chesapeake Bay Glossary; N-STEPS Online Glossary of Terms",
    "Superfund for Students and Teachers Glossary",
    "Terms of Environment",
    "Coastal Sensitivity to Sea-level Rise Glossary and Acronyms",
    "Environmental Modeling and Assessment Program (EMAP) Master Glossary",
    "NOAA Glossary of Coastal Terminology",
    "USGS Water Science Glossary of Terms",
    "40 CFR 125.93 (CFR 2013)",
    "NSTEPS Online Glossary of Terms",
    "40 CFR 35.2005 (CFR 2018)",
    "Aquatic Resources Glossary"
  ],
  "url": "https://mlchart.com/terminology/environment/estuary/"
}