water moccasin or cotton mouth Either of two species of pit viper that inhabits marshy lowlands of the southeastern U.S. and Mexico. The U.S. species ( Agkistrodon piscivorus ) is called a cottonmouth because it threatens with the mouth open, showing the white interior. It is up to 5 ft (1.5 m) long and is completely black or brown with darker crossbands. A dangerous snake with a potentially lethal bite, it tends to stand its ground or move slowly away when alarmed. It will eat almost any small animal, including turtles, fishes, and birds. See also copperhead.
water ouzel See dipper
water pollution State resulting when substances are released into a body of water, where they become dissolved or suspended in the water or deposited on the bottom, accumulating to the extent that they over¬ whelm its capacity to absorb, break down, or recycle them, and thus inter¬ fering with the functioning of aquatic ecosystems. Contributions to water pollution include substances drawn from the air (see acid rain), silt from soil erosion, chemical fertilizers and pesticides, runoff from septic tanks, outflow from livestock feedlots, chemical wastes (some toxic) from indus¬ tries, and sewage and other urban wastes from cities and towns. A com¬ munity far upstream in a watershed may thus receive relatively clean water, whereas one farther downstream receives a partly diluted mixture of urban, industrial, and rural wastes. When organic matter exceeds the capacity of microorganisms in the water to break it down and recycle it, the excess of nutrients in such matter encourages algal water blooms. When these algae die, their remains add further to the organic wastes already in the water, and eventually the water becomes deficient in oxy¬ gen. Organisms that do not require oxygen then attack the organic wastes, releasing gases such as methane and hydrogen sulfide, which are harm¬ ful to the oxygen-requiring forms of life. The result is a foul-smelling, waste-filled body of water. See also eutrophication.
water polo Sport played in a swimming pool by teams of seven with a buoyant ball resembling a football (soccer ball). The ball may be car¬ ried or thrown, and a point is scored when the ball is placed in the oppos¬ ing team’s goal. The name derives from a mid-19th-century version of the sport in which players rode barrels and struck the ball with sticks. A rough and demanding game, it is played by both men and women. Mod¬ ern water polo was introduced as an Olympic sport in 1900.
European species are less water-dependent and lay eggs. In defense they inflate the head, strike, and release a foul secretion. Average length is about 3 ft (1 m); some Old World species reach 6 ft (1.8 m).
water-supply system Facilities for the collection, treatment, stor¬ age, and distribution of water. Ancient systems included wells, storage reservoirs, canals and aqueducts, and water-distribution systems. Highly advanced systems appeared c. 2500 bc and reached their peak in the Roman aqueduct system. In the Middle Ages, water supplies were largely neglected and epidemics caused by waterborne organisms were common. In the 17th-18th century, distribution systems utilizing cast-iron pipes, aqueducts, and pumps began to be installed. The link between polluted water and disease came to be understood in the 19th century, and treat¬ ment methods such as slow sand filtration and disinfection with chlorine were introduced. Modem reservoirs are formed usually by constructing dams near the collection point of mountain-water runoff or across rivers. After the water reaches collection points, it is treated to improve its qual¬ ity; it is then pumped either directly into a city or town’s distribution sys¬ tem or to an elevated storage location, such as a water tank. See also plumbing.
water table or groundwater table Surface of a body of under¬ ground water below which the soil or rocks are permanently saturated with water. The water table separates the groundwater zone (zone of satu¬ ration) that lies below it from the zone of aeration that lies above it. The water table fluctuates both with the seasons and from year to year because it is affected by climatic variations and by the amount of precipitation used by vegetation. It also is affected by withdrawing excessive amounts of water from wells or by recharging them artificially. See also aquifer.
marsh
present water table (wet season)
aerated
zone
stream
lake
dry-season water table
saturated
zone
Seasonal variations in groundwater levels.
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waterbuck Species of antelope ( Kobus ellipsiprymnus ) that lives in herds, usually near water, on plains and floodplains and in woodlands and swamps of sub-Saharan Africa. Waterbucks are almost 5 ft (1.5 m) high at the shoulder. Males have long, heavily ridged horns that curve back¬ ward and then upward. The coarse, shaggy coat is grayish, and the rump has a white ring.
Waterbury City (pop., 2000: 107,271), western Connecticut, U.S. Located on the Naugatuck River, Mattatuck Plantation was settled in 1674 as part of Farmington, Conn., and was later incorporated (1686) as the town of Waterbury. The city of Waterbury, incorporated in 1853, was con¬ solidated with the town in 1902. In the 19th century it became the nation’s largest producer of brass products. Other manufactures include clocks, watches, and chemicals. It is the financial and commercial centre of west¬ ern Connecticut.
water resource Any of the entire range of natural waters (vapour, liq¬ uid, or solid) that occur on the Earth and that are of potential use to humans. These resources include the waters of the oceans, rivers, and lakes; groundwater and deep subsurface waters; and glaciers and perma¬ nent snowfields. Continuing increase in water use has led to growing con¬ cern over the availability and quality of water supplies.
water snake Any of 65-80 snake species of the genera Natrix and Nerodia, as well as similar snakes of the family Colubridae, found world¬ wide except in South America. Most species have a stout body with dark blotches or streaks and ridged scales. Some are simliar in appearance to venomous species. They kill fishes and amphibians with a nonvenomous bite. The New World species live in or near water and bear live young;
watercolour Painting made with a pigment ground in gum, usually gum arabic, and applied with brush and water to a surface, usually paper. The pigment is ordinarily transparent but can be made opaque by mixing with a whiting to produce GOUACHE. Transparent watercolour allows for freshness and luminosity. Whereas oil paintings achieve their effects by a building up of colour, watercolours rely on what is left out, with empty, unpainted spaces being an integral part of the work.
watercress Perennial plant ( Nasturtium officinale ) of the mustard fam¬ ily, native to Eurasia and naturalized throughout North America. It grows submerged, floating on the water, or spread over mud surfaces in cool, flowing streams. White flowers are followed by small, beanlike seedpods. Watercress is often cultivated in tanks for its young shoots, which are used
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Wateree River ► Waterton Lakes National Park I 2035
in salads. The delicate, light green, peppery-flavoured leaves are rich in vitamin C. Since watercress grown near cattle and sheep feedlots can become contaminated by feces containing cysts of the liver fluke, agent of the illness fascioliasis (liver rot), regulations specify that commercial watercress beds be protected from such pollution.
Wateree River River, central South Carolina, U.S. It enters the state from North Carolina as the Catawba River but is known as the Wateree in South Carolina. It joins the Congaree River to form the Santee River. The Wateree-Catawba River is 395 mi (636 km) long. The Wateree flows through a series of lakes and reservoirs, the largest of which is Wateree Lake, 15 mi (24 km) long.