This article is unconnected to the various rivers named Blackwater: see Blackwater River (note capitalization)

Blackwater rivers are rivers with waters colored like clear tea to coffee. Most major blackwater rivers are in the Amazon River system and the American South.

Amazon River tributary classified as blackwater

Manaus, the largest city on the Amazon River, as seen from a NASA satellite image, surrounded by the muddy Amazon River and the blackwater Negro River.

A blackwater river is one with a deep, slow-moving channel that flows through forested swamps and wetlands. The term blackwater describes the appearance of the water of such rivers, which is a dark coffee color. This color results from the leaching of tannins from the decaying leaves of adjoining vegetation.

Blackwater rivers are also characterized by striking water clarity; so clear that visibility regularly exceeds 30 feet (9 meters). However, after rainstorms blackwater rivers can lose their typical clarity and color while sediment runs off from the surrounding forest. Within a few hours to a few days, the normal conditions return.

Chemically, blackwater rivers are very low in dissolved minerals and often have no measurable water hardness. The very acidic, almost sterile water, with a pH of 3.5-6, keeps parasite and bacterial populations to a minimum. For this reason, blackwater rivers are considered some of the cleanest natural waters in the world, most often compared to "slightly contaminated distilled water." The water chemistry of blackwater also inhibits the proliferation of insect larvae, so the forests around blackwater rivers tend to have less floor-dwelling mosquitoes. This chemistry also makes blackwater rivers unsuitable for public water supplies.

Blackwater rivers of the world:

Amazonia

• Apaporis River: A tributary of the Yapura River.
• Arapuins River: A tributary of the Tapajós River.
• Negro River: By far the largest blackwater river in the world, one of the largest Amazonian tributaries.
• Tahuayo River
• Tefé River

American South

• Black River, a tributary of the Pee Dee River in North and South Carolina in the United States.
• Cape Fear River: A large river in North Carolina in the United States flowing into the Atlantic Ocean.
• Cashie River: A river in North Carolina in the United States flowing into Albemarle Sound.
• Chowan River: A river in North Carolina in the United States flowing into Albemarle Sound.
• Edisto River: A large river in United States flowing into the Atlantic Ocean.
• Great Coharie Creek: A river in North Carolina in the United States flowing into the Black River.
• Little Pee Dee River: A river in South Carolina in the United States flowing into the Pee Dee River.
• Lumber/Drowning Creek: A river in North and South Carolina in the United States.
• Suwannee River: A large river in southern Georgia and northern United States flowing into the Gulf of Mexico.
• Upper Little River: A river in North Carolina in the United States flowing into the Cape Fear River.
• Waccamaw River: A river in North and South Carolina in the United States flowing into the Atlantic Ocean.
• White Oak River: A river in United States flowing into the Atlantic Ocean.

American North

• Tahquamenon River: A river in the Upper Peninsula of Michigan flowing into Lake Superior.

See also

• Blackwater River, a list of rivers by this name.

Resources

• River Types of the Amazon, blackwater partway down the page (http://www.mongabay.com/0602.htm)