A blackwater river is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 with a deep, slow-moving channel that flows through forested swamp

Swamp

A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...

s and wetland

Wetland

A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

s. As vegetation decays in the water, tannin

Tannin

A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The term tannin refers to the use of...

s are leached out, resulting in transparent, acidic water that is darkly stained, resembling tea

Tea

Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...

 or coffee

Coffee

Coffee is a brewed beverage with a dark,init brooo acidic flavor prepared from the roasted seeds of the coffee plant, colloquially called coffee beans. The beans are found in coffee cherries, which grow on trees cultivated in over 70 countries, primarily in equatorial Latin America, Southeast Asia,...

. Most major blackwater rivers are in the Amazon River

Amazon River

The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...

 system and the Southern United States

Southern United States

The Southern United States—commonly referred to as the American South, Dixie, or simply the South—constitutes a large distinctive area in the southeastern and south-central United States...

. The term "blackwater" here is an agreed-upon technical one in fluvial

Fluvial

Fluvial is used in geography and Earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them...

 studies, geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, geography

Geography

Geography is the science that studies the lands, features, inhabitants, and phenomena of Earth. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...

 and ecology

Ecology

Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

/biology

Biology

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

. Not all dark-colored rivers are true blackwater rivers in the technical sense. Some rivers in temperate regions, which drain or flow through areas of dark black loam

Loam

Loam is soil composed of sand, silt, and clay in relatively even concentration . Loam soils generally contain more nutrients and humus than sandy soils, have better infiltration and drainage than silty soils, and are easier to till than clay soils...

, are colored black due to the color of the soil. These types of rivers can be referred to as black mud rivers; there are also black mud estuaries

Estuary

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

 (see link above to rivers officially named Blackwater River.)

Blackwater rivers are much lower in nutrients than whitewater

Whitewater

Whitewater is formed in a rapid, when a river's gradient increases enough to disturb its laminar flow and create turbulence, i.e. form a bubbly, or aerated and unstable current; the frothy water appears white...

 rivers and have ionic concentrations

Ionic strength

The ionic strength of a solution is a measure of the concentration of ions in that solution. Ionic compounds, when dissolved in water, dissociate into ions. The total electrolyte concentration in solution will affect important properties such as the dissociation or the solubility of different salts...

 only slightly higher than rain

Rain

Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...

water. The unique water conditions lead to a composition of flora and fauna that differs significantly from that found in whitewater sources. Areas where blackwater rivers and whitewater rivers combine are particularly attractive to a diverse group of organisms.

Comparison between white and black waters

Table 1: Mean ionic composition, specific conductivity (μS/cm), and pH

PH

In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 in Amazon

Amazon River

The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...

 waters.

	Solimões or Amazon River Amazon River The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...  – whitewater.	Rio Negro – blackwater.
Na Sodium Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...  (mg/L)	2.3 ± 0.8	0.380 ± 0.124
K Potassium Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...  (mg/L)	0.9 ± 0.2	0.327 ± 0.107
Mg Magnesium Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...  (mg/L)	1.1 ± 0.2	0.114 ± 0.035
Ca Calcium Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...  (mg/L)	7.2 ± 1.6	0.212 ± 0.066
Cl Chlorine Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...  (mg/L)	3.1 ± 2.1	1.7 ± 0.7
Si Silicon Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...  (mg/L)	4.0 ± 0.9	2.0 ± 0.5
Sr Strontium Strontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...  (μg/L)	37.8 ± 8.8	3.6 ± 1.0
Ba Barium Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...  (μg/L)	22.7 ± 5.9	8.1 ± 2.1
Al (μg/L)	44 ± 37	112 ± 29
Fe Iron Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...  (μg/L)	109 ± 76	178 ± 58
Mn Manganese Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...  (μg/L)	5.9 ± 5.1	9.0 ± 2.4
Cu Copper Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...  (μg/L)	2.4 ± 0.6	1.8 ± 0.5
Zn Zinc Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...  (μg/L)	3.2 ± 1.5	4.1 ± 1.8
Conductivity	57 ± 8	9 ± 2
pH PH In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...	6.9 ± 0.4	5.1±0.6
Total P Phosphorus Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...  (μg/L)	105 ± 58	25 ± 17
Total C Carbon Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...  (mg/L)	13.5 ± 3.1	10.5 ± 1.3
HCO3-C (mg/L)	6.7 ± 0.8	1.7 ± 0.5

Black and white waters differ significantly in their ionic composition, as shown in Table 1. Black waters are much more acid

Acid

An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ic, resulting in an aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 concentration greater than that of the more neutral white waters. The major difference is the concentrations of sodium

Sodium

Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, magnesium

Magnesium

Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

, calcium

Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

 and potassium

Potassium

Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

; these are very low in black waters. This has considerable ecological implications. As some animal groups, such as snail

Snail

Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

s, need much calcium with which to build their shells, they are not abundant in black waters. The lack of dissolved ions in black waters results in a low conductivity, similar to that of rainwater.

Black and white waters also differ in their plankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

ic fauna

Fauna

Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...

 and flora

Flora

Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...

. Tables 2 and 3 compare the number of planktonic animals caught in black and white water localities only a few meters apart. In fact, the black water was not as extreme an example as can be found in the Rio Negro system. However, it can be seen that the black water held far greater numbers of rotifer

Rotifer

The rotifers make up a phylum of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris in 1696, and other forms were described by Anton van Leeuwenhoek in 1703...

s but fewer crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s and mite

Mite

Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...

s. These crustaceans are important foods for larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

l fish. The zones where the two waters mix are particularly attractive to ostracod

Ostracod

Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. Some 65,000 species have been identified, grouped into several orders....

s and young fish. These mixing zones tend to have high numbers of animals. The high abundance of animals is shown clearly in Table 3, which compares the numbers of animals present in 10 litres of water in each habitat sampled.

Table 2: Different plankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

ic organisms collected in black (Japura

Japurá River

The Japurá River or Caquetá River is a river about long rising as the Caquetá River in the Andes in the Southwest of Colombia. It flows southeast into Brazil, where it is called the Japurá. The Japurá enters the Amazon River through a network of channels...

) and white (Solimoes) waters.

Animal groups present	Black water	Mixed water	White water
Rotifer Rotifer The rotifers make up a phylum of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris in 1696, and other forms were described by Anton van Leeuwenhoek in 1703... a	284	23	0
Cladocera Cladocera Cladocera is an order of small crustaceans commonly called water fleas. Around 620 species have been recognised so far, with many more undescribed. They are ubiquitous in inland aquatic habitats, but rare in the oceans. Most are long, with a down-turned head, and a carapace covering the apparently...	5	29	43
Ostracod Ostracod Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. Some 65,000 species have been identified, grouped into several orders.... a	39	97	29
Calanoida Calanoida Calanoida is an order of copepods, a kind of zooplankton. They include around 40 families with about 1800 species of both marine and freshwater copepods. Calanoid copepods are dominant in the plankton in many parts of the world's oceans, making up 55%–95% of plankton samples...	11	51	66
Cyclopoida Cyclopoida Cyclopoida is an order of small crustaceans from the subclass Copepoda. Like many other copepods, members of Cyclopoida are small, planktonic animals living both in the sea and in freshwater habitats. They are capable of rapid movement...	22	49	61
Chironomidae Chironomidae Chironomidae are a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae...	0	3	3
Acari (mites)	0	0	2

Table 3: Number of plankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

ic organisms collected in 10 L of black, white and mixed waters.

	Black water		Mixed water		White water
Animal groups present	Open water	Forest	Open water	Forest	Open water	Forest
Volvocaceae Volvocaceae The Volvocaceae are a family of unicellular or colonial biflagellates, including the typical genus Volvox. The family was named by Ehrenberg in 1834, and is known in older classifications as the Volvocidae.- Description :...	42		38
Rotifer Rotifer The rotifers make up a phylum of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris in 1696, and other forms were described by Anton van Leeuwenhoek in 1703... a	87	5	34
Cladocera Cladocera Cladocera is an order of small crustaceans commonly called water fleas. Around 620 species have been recognised so far, with many more undescribed. They are ubiquitous in inland aquatic habitats, but rare in the oceans. Most are long, with a down-turned head, and a carapace covering the apparently...	6		5		8	1
Ostracod Ostracod Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. Some 65,000 species have been identified, grouped into several orders.... a	2	11	3		7
Calanoida Calanoida Calanoida is an order of copepods, a kind of zooplankton. They include around 40 families with about 1800 species of both marine and freshwater copepods. Calanoid copepods are dominant in the plankton in many parts of the world's oceans, making up 55%–95% of plankton samples...	23	3	10
Cyclopoida Cyclopoida Cyclopoida is an order of small crustaceans from the subclass Copepoda. Like many other copepods, members of Cyclopoida are small, planktonic animals living both in the sea and in freshwater habitats. They are capable of rapid movement...	5	27	19	1	13	1
Mysidacea Mysidacea Mysida is a group of small, shrimp-like crustaceans, an order in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch, or marsupium, in females. Mysids are mostly found in marine waters throughout the world, but are also important in...		1
Diptera Diptera Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...					1
Acari (mites)			1		1
Larval fish			1		1

Amazonia

• Apaporis River: A tributary of the Yapura River.
• Arapiuns River
  Arapiuns River
  -References:*...
  
  : A tributary of the Tapajós River.
• Coari River
  Coari River
  Coari River is a river of Amazonas state in north-western Brazil.-References:*...
  
  
• Mirití-Paraná River
• Rio Negro: The largest blackwater river in the world; one of the largest Amazonian tributaries.
• Piorini River
  Piorini River
  Piorini River is a river of Amazonas state in north-western Brazil.-References:*...
  
  
• Tahuayo River
• Tefé River
  Tefé River
  Tefé River is a river of Amazonas state in north-western Brazil. It is a tributary of the Amazon, which it meets at the city of Tefé.-References:*...
  
  
• Uatamã River
• Urubu River
  Urubu River
  -Brazil:* Urubu River * Urubu River * Urubu River * Urubu Grande River...
  
  
• Vaupés

Orinoco basin

• Atabapo
  Atabapo River
  Atabapo River is a river of Venezuela and Colombia. It forms the international boundary between the two countries for much of its length. It is part of the Orinoco River basin.-References:*Rand McNally, The New International Atlas, 1993....
  
  : from the Guiana
  Guayana Region
  The Guayana Region is an administrative region of Venezuela.The region has a population of 1,383,297 inhabitants and a territory of 458,344 km². It borders the independent nation of Guyana which forms part of The Guyanas...
  
   Highlands of Venezuela
  Venezuela
  Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
  
   west into the Orinoco
  Orinoco
  The Orinoco is one of the longest rivers in South America at . Its drainage basin, sometimes called the Orinoquia, covers , with 76.3% of it in Venezuela and the remainder in Colombia...
  
  
• Caroní River
  Caroní River
  The Caroni River is the second most important river of Venezuela, the second in flow, and one of the longest, 952 km from the Tepui Kuquenan, where she originates with the same name Kuquenan, up to its confluence with the River Orinoco to which basin she belongs...
  
  : from the Guiana Highlands of Venezuela west into the Orinoco
• Inírida
  Inírida River
  -References:*Rand McNally, The New International Atlas, 1993....
  
  : from Colombia
  Colombia
  Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
  
   northeast into the Guaviare River
  Guaviare River
  The Guaviare is a tributary of the Orinoco located in Colombia.The Guaviare has its source in two other rivers, the Ariari and the Guayabero, which in turn have their own sources in the eastern part of the Andes. At long, it is the longest river on the Orinoco and is navigable for of its total...
  
   which flows into the Orinoco
• Ventuari
  Ventuari River
  The Ventuari River is a river in the Orinoco basin in Venezuela. The Ventuari flows from eastern Venezuela in the Guiana Highlands southwest into the Orinoco River. It is 520 km long and its major tributary is the Manapiare River.-References:...
  
  : from eastern Venezuela southwest into the Orinoco
• Vichada
  Vichada River
  The Vichada River is a blackwater river in the country of Colombia, South America. It flows into the Orinoco River.The westward course of the Vichada is offset by an impact structure, called the Vichada Structure. The structure is most likely the largest impact structure in South America....
  
  : from Colombia
  Colombia
  Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
  
   east into the Orinoco
• Tomo: from Colombia east into the Orinoco
• Tuparro
  Tuparro River
  Tuparro River is a river of Colombia found in Vichada Department. It gives its name to El Tuparro National Natural Park. Tuparro is part of the Orinoco River basin....
  
  : from Colombia east into the Orinoco

Southern United States

• Ashepoo River
  Ashepoo River
  Ashepoo River is a short blackwater river in South Carolina. It rises in a confluence of swamps south of Walterboro, flows in southeast direction and then empties into Saint Helena Sound at . The entire course of the river lies within the boundaries of Colleton County...
  
  : Along with the Edisto and the Combahee Rivers in South Carolina makes up the ACE Basin National Wildlife Refuge.
• Big Cypress, Black Cypress, and Little Cypress
  Cypress Bayou
  Cypress Bayou is the name applied to a series of wetlands at the western edge of Caddo Lake, in and around Jefferson, Texas, making up part of the largest Cypress forest in the world. The bayou is divided into three areas—each part of the watershed of a small river or creek—Little...
  
   and the small rivers in the watershed of Caddo Lake
  Caddo Lake
  Caddo Lake is a lake and wetland located on the border between Texas and Louisiana, in northern Harrison County and southern Marion County in Texas and western Caddo Parish in Louisiana. The lake is named after the Southeastern culture of Native Americans called Caddoans or Caddo, who lived in...
  
   in Texas and Louisiana.
• Blackwater River
  Blackwater River (Chowan River)
  The Blackwater River of southeastern Virginia flows from its source near the city of Petersburg, Virginia for about 105 miles through the Inner Coastal Plain region of Virginia . The Blackwater joins the Nottoway River to form the Chowan River, which empties into Albemarle Sound...
  
  : a tributary of the Chowan River
  Chowan River
  The Chowan River is a blackwater river formed with the merging of Virginia's Blackwater and Nottoway rivers near the stateline between Virginia and North Carolina. According to the USGS a variant name is Choan River....
  
   in Virginia.
• Blackwater River
  Blackwater River (Florida)
  The Blackwater River of Florida is a river rising in southern Alabama and flowing through the Florida Panhandle to the Gulf of Mexico. The river enters Florida in Okaloosa County and flows through Santa Rosa County to Blackwater Bay, an arm of Pensacola Bay. The river passes through Blackwater...
  
  : a major river in the western Florida panhandle
  Florida Panhandle
  The Florida Panhandle, an informal, unofficial term for the northwestern part of Florida, is a strip of land roughly 200 miles long and 50 to 100 miles wide , lying between Alabama on the north and the west, Georgia also on the north, and the Gulf of Mexico to the south. Its eastern boundary is...
  
  .
• Black River
  Black River (South Carolina)
  The Black River is a blackwater river in South Carolina in the United States....
  
  : a tributary of the Pee Dee River
  Pee Dee River
  The Pee Dee River, also known as the Great Pee Dee River, is a river in North Carolina and South Carolina. It originates in the Appalachian Mountains in North Carolina, where its upper course above the mouth of the Uwharrie River is known as the Yadkin River. It is extensively dammed for flood...
  
   in North
  North Carolina
  North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
  
   and South Carolina.
• Cape Fear River
  Cape Fear River
  The Cape Fear River is a long blackwater river in east central North Carolina in the United States. It flows into the Atlantic Ocean near Cape Fear, from which it takes its name. The overall water quality of the river is continuously measured and monitored by and conducted by the , , and the...
  
  , North Carolina: flows into the Atlantic Ocean.
• Cashie River, North Carolina: flows into Albemarle Sound
  Albemarle Sound
  Albemarle Sound is a large estuary on the coast of North Carolina in the United States located at the confluence of a group of rivers, including the Chowan and Roanoke. It is separated from the Atlantic Ocean by the Outer Banks, a long barrier peninsula upon which the town of Kitty Hawk is located,...
  
  .
• Caloosahatchee River
  Caloosahatchee River
  The Caloosahatchee River is a river on the southwest Gulf Coast of Florida in the United States, approximately long. It drains rural areas on the northern edge of the Everglades northwest of Miami...
  
  , Florida
  Florida
  Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
  
  : flows west from Lake Okeechobee
  Lake Okeechobee
  Lake Okeechobee , locally referred to as The Lake or The Big O, is the largest freshwater lake in the state of Florida. It is the seventh largest freshwater lake in the United States and the second largest freshwater lake contained entirely within the lower 48 states...
  
   to the Gulf of Mexico
  Gulf of Mexico
  The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
  
  .
• Chowan River
  Chowan River
  The Chowan River is a blackwater river formed with the merging of Virginia's Blackwater and Nottoway rivers near the stateline between Virginia and North Carolina. According to the USGS a variant name is Choan River....
  
  , North Carolina: flows into Albemarle Sound.
• Edisto River
  Edisto River
  The Edisto River is the longest completely undammed / unleveed blackwater river in North America, flowing 206 meandering miles from its sources in Saluda and Edgefield counties, to its Atlantic Ocean mouth at Edisto Beach, SC...
  
  , South Carolina: flows into the Atlantic Ocean; the longest undammed, unleveed blackwater river in North America.
• Econlockhatchee River
  Econlockhatchee River
  The Econlockhatchee River is a north-flowing blackwater tributary of the St. Johns River that flows through Orange, Seminole, and Osceola counties in Florida. Its name means "River of mounds"...
  
  , a tributary
  Tributary
  A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...
  
   of the St. Johns River
  St. Johns River
  The St. Johns River is the longest river in the U.S. state of Florida and its most significant for commercial and recreational use. At long, it winds through or borders twelve counties, three of which are the state's largest. The drop in elevation from the headwaters to the mouth is less than ;...
  
   in Central Florida.
• Four Hole Swamp, a tributary of the Edisto River in South Carolina.
• Great Coharie Creek, North Carolina: flows into the Black River.
• Little Pee Dee River
  Little Pee Dee River
  The Little Pee Dee River is a tributary of the Pee Dee River . The Little Pee Dee technically arises near Laurinburg, North Carolina as Gum Swamp, which flows southward, receiving several small tributaries, across the South Carolina border into Red Bluff Lake, near McColl, South Carolina...
  
  , South Carolina: flows into the Pee Dee River
  Pee Dee River
  The Pee Dee River, also known as the Great Pee Dee River, is a river in North Carolina and South Carolina. It originates in the Appalachian Mountains in North Carolina, where its upper course above the mouth of the Uwharrie River is known as the Yadkin River. It is extensively dammed for flood...
  
  .
• Lynches River
  Lynches River
  Lynches River, named for Thomas Lynch, Jr., signer of the Declaration of Independence, rises in North Carolina near Waxhaw, North Carolina, at about 700 feet elevation, flowing only a short distance to the South Carolina border, and thence to join the Pee Dee River nearJohnsonville...
  
  , South Carolina: flows into the Pee Dee River
  Pee Dee River
  The Pee Dee River, also known as the Great Pee Dee River, is a river in North Carolina and South Carolina. It originates in the Appalachian Mountains in North Carolina, where its upper course above the mouth of the Uwharrie River is known as the Yadkin River. It is extensively dammed for flood...
  
  .
• Lumber
  Lumber River
  The Lumber River is a river in south-central North Carolina in the flat Coastal Plain. European settlers first called the river Drowning Creek, which still is the name of its headwater. The waterway known as the Lumber River extends downstream from the Scotland County-Hoke County border to the...
  
  /Drowning Creek: located in North and South Carolina. Part of Lumber River State Park
  Lumber River State Park
  Lumber River State Park is a North Carolina state park along the Lumber River in Scotland, Hoke, Robeson and Columbus counties in the United States. It covers 9234 acres along a 115-mile stretch of the Lumber River. Lumber River State Park is located in North Carolina's Coastal Plain...
  
  
• Ogeechee River
  Ogeechee River
  Ogeechee River is a river in the U.S. state of Georgia. It heads at the confluence of its North and South Forks, about south-southwest of Crawfordville and flowing generally southeast to Ossabaw Sound about south of Savannah. Its largest tributary is the Canoochee River...
  
  : A 245-mile river in eastern Georgia
  Georgia (U.S. state)
  Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
  
   that passes to the south of the city of Savannah
  Savannah, Georgia
  Savannah is the largest city and the county seat of Chatham County, in the U.S. state of Georgia. Established in 1733, the city of Savannah was the colonial capital of the Province of Georgia and later the first state capital of Georgia. Today Savannah is an industrial center and an important...
  
   and enters the Atlantic Ocean at Ossabaw Sound.
• Pithlachascotee River
  Pithlachascotee River
  The Pithlachascotee River, often called the Cotee or "Cootie" River, is a blackwater river in Pasco County, Florida.Originating near Crews Lake, the river flows for over to the south and west, flowing through the Starkey Wilderness Park before turning northwest through downtown New Port Richey,...
  
  : A small river in central Florida
  Florida
  Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
  
  .
• Santa Fe River
  Santa Fe River
  The Santa Fe River is a river in northern Florida. The watershed of the river is approximately and spreads across southern Columbia, southern Suwannee, western Bradford, far southern Baker, Union, northern and eastern Gilchrist, and northern Alachua counties. The headwaters of the river are...
  
  : A river in northern Florida.
• Satilla River
  Satilla River
  The Satilla River rises in Ben Hill County, Georgia, near the town of Fitzgerald, and flows in a mostly easterly direction to the Atlantic Ocean. Along its approximately course are the cities of Waycross, Waynesville, and Woodbine. The Satilla drains almost of land, all of it in the coastal...
  
  : A river in southeast Georgia
  Georgia (U.S. state)
  Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
  
   that flows through the city of Waycross
  Waycross, Georgia
  Waycross is the county seat of, and only incorporated city in, Ware County in the U.S. state of Georgia. The population was 14,725 at the 2010 Census. A small portion of the city extends into Pierce County. According the U.S...
  
   and empties into the Atlantic Ocean near Cumberland Island
  Cumberland Island
  Cumberland Island is one of the Sea Islands. Cumberland is the largest in terms of continuously exposed land area of Georgia's barrier islands. It is located on the Atlantic Ocean off the coast of the U.S. state of Georgia and is part of Camden County...
  
  .
• Scuppernong River
  Scuppernong River (North Carolina)
  The Scuppernong River is a blackwater river that flows through Tyrrell County and Washington County, North Carolina into the Albemarle Sound. It is a tributary of the Pasquotank River Basin...
  
  : A small river in Washington
  Washington County, North Carolina
  -Demographics:As of the census of 2000, there were 13,723 people, 5,367 households, and 3,907 families residing in the county. The population density was 39 people per square mile . There were 6,174 housing units at an average density of 18 per square mile...
  
   and Tyrrell Counties
  Tyrrell County, North Carolina
  -Demographics:Tyrrell County was as of 2000 the least populous county in North Carolina.As of the census of 2000, there were 4,149 people, 1,537 households, and 1,055 families residing in the county. The population density was 11 people per square mile . There were 2,032 housing units at an...
  
   in eastern North Carolina
  North Carolina
  North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
  
   at Pettigrew State Park
  Pettigrew State Park
  Pettigrew State Park is a North Carolina State Park in Tyrrell and Washington Counties, North Carolina in the United States. It covers around the shore lines of Lake Phelps and the Scuppernong River. The park's developed facilities are south of U.S. Route 64 near Roper and Creswell, North Carolina...
  
  .

St. Marys River (Georgia): http://www.saintmarysriver.org/history.html

• St. Johns River
  St. Johns River
  The St. Johns River is the longest river in the U.S. state of Florida and its most significant for commercial and recreational use. At long, it winds through or borders twelve counties, three of which are the state's largest. The drop in elevation from the headwaters to the mouth is less than ;...
  
  : The largest river in Florida. Flows north through Jacksonville
  Jacksonville, Florida
  Jacksonville is the largest city in the U.S. state of Florida in terms of both population and land area, and the largest city by area in the contiguous United States. It is the county seat of Duval County, with which the city government consolidated in 1968...
  
   and into the Atlantic.
• Suwannee River
  Suwannee River
  The Suwannee River is a major river of southern Georgia and northern Florida in the United States. It is a wild blackwater river, about long. The Suwannee River is the site of the prehistoric Suwannee Straits which separated peninsular Florida from the panhandle.-Geography:The river rises in the...
  
  : A large river in southern Georgia
  Georgia (U.S. state)
  Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
  
   and northern Florida flowing into the Gulf of Mexico.
• Upper Little River, North Carolina: flows into the Cape Fear River
  Cape Fear River
  The Cape Fear River is a long blackwater river in east central North Carolina in the United States. It flows into the Atlantic Ocean near Cape Fear, from which it takes its name. The overall water quality of the river is continuously measured and monitored by and conducted by the , , and the...
  
  .
• Blackwater River
  Blackwater River (West Virginia)
  The Blackwater River is a river in the Allegheny Mountains of eastern West Virginia, USA. Via the Black Fork, it is a principal tributary of the Cheat River. Via the Cheat, the Monongahela and the Ohio rivers, it is part of the watershed of the Mississippi River and drains an area of...
  
  , West Virginia: Located in the Blackwater Canyon
  Blackwater Canyon
  Blackwater Canyon is a rugged, heavily-wooded, eight-mile long gorge carved by the Blackwater River in the Allegheny Mountains of eastern West Virginia, USA...
  
   in Tucker County. Blackwater Falls a five-story waterfall is located along this river with rapids ranging from Class III-V+
• Waccamaw River
  Waccamaw River
  The Waccamaw River is a river, approximately 140 miles long, in southeastern North Carolina and eastern South Carolina in the United States. It drains an area of approximately 1110 square miles in the coastal plain along the eastern border between the two states into the Atlantic Ocean...
  
  , North and South Carolina: flows into the Atlantic Ocean.
• White Oak River
  White Oak River
  The White Oak River is a blackwater river, approximately 40 mi long, on the coastal plain of southeast North Carolina in the United States. It empties in the Atlantic Ocean.-Course:...
  
  , North Carolina: flows into the Atlantic Ocean.

Northern United States

• Black River
  Black River (New York)
  The Black River is a blackwater river that empties into the eastern end of Lake Ontario on the shore of Jefferson County, New York in the United States of America...
  
  , New York
  New York
  New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
  
  : A river starting in the western Adirondacks that flows into Lake Ontario
  Lake Ontario
  Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
  
  .
• Tahquamenon River
  Tahquamenon River
  The Tahquamenon River is a long blackwater river in the U.S. state of Michigan that flows in a generally eastward direction through the eastern end of the Upper Peninsula. It drains approximately of the Upper Peninsula, including large sections of Luce County and Chippewa County...
  
  , Michigan
  Michigan
  Michigan is a U.S. state located in the Great Lakes Region of the United States of America. The name Michigan is the French form of the Ojibwa word mishigamaa, meaning "large water" or "large lake"....
  
  : A river in the Upper Peninsula that flows into Lake Superior
  Lake Superior
  Lake Superior is the largest of the five traditionally-demarcated Great Lakes of North America. It is bounded to the north by the Canadian province of Ontario and the U.S. state of Minnesota, and to the south by the U.S. states of Wisconsin and Michigan. It is the largest freshwater lake in the...
  
  .
• Tuckahoe River
  Tuckahoe River
  Tuckahoe River may refer to:*Tuckahoe River , river in southern New Jersey*Tuckahoe Creek, in Maryland...
  
  , New Jersey
  New Jersey
  New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
  
  : A short river in southern New Jersey that flows into Great Egg Harbor.
• Gooseberry River: A river in northern Minnesota that leaches from peat bogs and pine forests.

Australia

• Gordon River
  Gordon River
  The Gordon River is one of the major rivers of Tasmania, Australia. It rises in the centre of the island at Lake Richmond and flows westward for about 193km where it empties into Macquarie Harbour on the West Coast of Tasmania. Major tributaries include the Serpentine River and the Franklin...
  
  , Tasmania
  Tasmania
  Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
  
  : A river rising in the centre of the island and flowing westward, emptying into Macquarie Harbour
  Macquarie Harbour
  Macquarie Harbour is a large, shallow, but navigable by shallow draft vessels inlet on the West Coast of Tasmania, Australia.-History:James Kelly wrote in his narrative "First Discovery of Port Davey and Macquarie Harbour" how he sailed from Hobart in a small open five-oared whaleboat to discover...
  
   on the West Coast
  West Coast, Tasmania
  The West Coast of Tasmania is the part of the state that is strongly associated with wilderness, mining and tourism, rough country and isolation...
  
  .

Europe

• Morava river, flowing into the Danube
  Danube
  The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....
  
  
• River Blackwater, is in Hampshire. UK. runs with the River Whitewater
  River Whitewater
  The River Whitewater rises at springs near Bidden Grange Farm between Upton Grey and Greywell. It flows northeast through Hampshire and is a tributary of the River Blackwater near Swallowfield. Its headwaters flow over chalk and there is little pollution making the River Whitewater rich in wildlife...
  
   eventually into the River Loddon
  River Loddon
  The River Loddon is a river in the English counties of Berkshire and Hampshire. It is a tributary of the River Thames, rising within the urban area of Basingstoke and flowing to meet the Thames near the village of Wargrave...
  
  .
• River Blackwater, is in Northern Ireland. it divdes coutny Armagh and county Tyroneit eventually runs into Lough Neagh.