A Report by The World Resources Institute in collaboration with The United Nations Environment Programme and The United Nations Development Programme
Pollution in freshwater is of three major types:
These types of pollution, their sources, and methods of control are discussed further in "Focus On River Basin Pollution," below.
In general, river water quality, as measured by biological oxygen demand, has improved in industrialized countries over the past 20 years because of increased sewage treatment. Switzerland, Denmark, the Netherlands, Sweden, and the Federal Republic of Germany have achieved nearly complete sewage treatment coverage; Japan has made considerable progress but still lags behind most other industrial countries (20)
Some progress has also occurred in reducing the concentrations of heavy metals in industrialized countries. For example, lead concentrations near the mouths of rivers in Canada, Japan, Belgium, the Federal Republic of Germany, and the United Kingdom generally decreased over the 1970 85 period (21). Concentrations of metals in the Rhine River have also declined slightly after decades of increases (22). Trends in metals besides lead and in toxic substances are less encouraging.
In developing countries, water quality trends remain difficult to ascertain because of deficiencies in the assessment of pollution sources and in the monitoring of groundwater and surface waters. Water quality is generally thought to be deteriorating, especially around urban areas. Few cities have sewage treatment facilities, and municipal water supplies are often neither treated nor disinfected, greatly increasing the risk of diarrhea and other gastrointestinal illnesses that are factors in infant mortality. Industrial discharges are usually poorly controlled (23). (See Table 11.1.)
A 1991 regional review of global water quality by the World Health Organization and United Nations Environment Programme listed several areas of special concern, including the following:
The conclusion of the 1981-90 International Drinking Water Supply and Sanitation Decade provides an opportunity for evaluating the world's progress in water and sanitation and for devising new strategies for the 1990s. This U.N. effort, an outgrowth of the United Nations Water Conference held in Mar del Plata, Argentina in 1977, called on countries to set realistic goals for the decade and to develop national water and sanitation plans. In addition, it called upon aid agencies to provide assistance to implement the plans.
Unfortunately, the goals of the decade were blocked by a sudden slowdown of economic growth in the developing countries. During the 1980s, many countries went through a difficult financial readjustment and were burdened with rising costs of external financing: simply keeping up with rapid population growth and urbanization was difficult (37).
Measuring progress in water and sanitation has been difficult because of a lack of adequate information. A U.N. document concluded that, with the exception of West Asia, most regions had merely kept pace with or even fallen behind population growth. In subSaharan Africa, for example, the number of people served roughly doubled, but the number of urban dwellers without safe water increased by 29 percent (38). By the year 2000, the number of urban dwellers lacking adequate water supplies may increase by 83 percent, and the number lacking adequate sanitation services by nearly as much. Making substantial progress in water and sanitation by the end of the decade would require roughly a tripling of investment over the average achieved during the 1980s (39).
Work is underway to develop new strategies for water and sanitation in the 1990s. A key event is the International Conference on Water and the Environment, to be held in Dublin in January 1992, which is scheduled to focus on six major issues:
The strategies and action plans developed at this conference will be presented to the United Nations Conference on Environment and Development in Brazil in June 1992 (40).
As the decade begins, economic issues--the gap between increasing costs and users' ability to pay, their efficient pricing of services, the promotion of incentives to conserve water--seem to predominate, along with the problem of institutional weaknesses in water resources management and planning. But as urban areas continue to grow, the problems of water availability are likely to be increasingly important, and options such as the reuse of wastewater and desalination may become increasingly attractive.
The land area drained by a river and its tributaries-- known as a river basin--is the basic unit for under standing the sources and effects of freshwater pollution as well as the ecological relationships between terrestrial and aquatic systems. Figure 11.3 shows the world's major river basins.
As water circulates from the atmosphere through the watershed and oceans and back into the atmosphere--a process known as the hydrological cycle--it is vulnerable to pollution from many sources. First, airborne dust, nutrients, metals, and other chemicals may fall as dry deposition or adhere to and fall with raindrops and snowflakes on both land and water. Second, as it flows over or filters through the soil, precipitation may dissolve nutrients and chemical residues or pick up nutrients, agricultural and industrial chemical residues, metals, and other pollutants. Eventually, some of the water may enter tributary streams and rivers, into which a third source of pollution--sewage and industrial wastewater--is discharged directly. At their mouths, rivers disgorge their loads of sediment and pollutants into coastal estuaries, where they may remain for many years. (See Chapter 12, "Oceans and Coasts," Focus On Coastal Pollution.)
In addition to producing chemical pollution, human activities affect aquatic ecosystems in a variety of ways. When cities are built, grasslands, forests, and wetlands are converted to irnpermeable surfaces such as roads, parking lots, and roofs, greatly altering streamflow patterns. In cities, on farms, and in logging operations, removal of streamside vegetation can promote streambank erosion and subsequent smothering of freshwater animals and plants by sediments. Dams for power or irrigation impede fish migration and alter water chemistry and temperature in downstream areas.
Throughout a river system, pollution of groundwater, surface waters, and ultimately coastal waters can directly and indirectly damage human health and economic activities, as well as aquatic plant and animal communities. The health impact is particularly severe in developing countries, where waterborne infectious diseases affect more people than any other health problem (41). Once polluted, freshwater, especially groundwater, is expensive to cleanse for human use.
Waterways degraded by development or pollution suffer decreased diversity and reduced abundance of fish and the invertebrates upon which fish and other animals feed (42) (43). Furthermore, in a process known as bioaccumulation, metals and inorganic chemicals may accumulate in aquatic organisms to levels well above those in the water itself, as the contaminants are passed up the food chain from prey to predator, including humans who consume fish. Finally, erosion resulting in sedimentation of waterways can impede navigation and require expensive dredging.
Pollution by upstream users can significantly reduce the quality of water available to downstream users (and ecosystems) at little or no cost to polluters. This greatly complicates efforts to maintain or restore water quality. The resulting conflicts can have local, national, and international ramifications. Within countries, agencies responsible for water quality have little or no control over activities-- such as siting of hazardous waste dumps, agricultural practices, or urban development--that influence the quality or quantity of available water (44) (45)
Most sources of pollution have been identified and technologies or processes have been devised to reduce each pollutant. Where watershed pollution continues, it is usually because of a lack of political will, intergovernmental coordination, or inadequate funding. Many governments are recognizing that the protection of freshwater and coastal water quality depends on integrated water resource management, which emphasizes river basin and coastal zone planning and involves agencies responsible for resource protection and for economic development (46) (47).
River basins are dominant features of the Earth's surface (48). They range in size from the tiny river basins along the mountainous Na Pali coast on Kauai in the Hawaiian islands to huge basins such as the Amazon River basin, which covers more than 7 million square kilometers, an area twice the size of India. Precipitation in a river basin can depend on continental-scale weather systems. For example, weather systems moving across the industrialized midwestern United States pick up pollutants that fall as acid precipitation in eastern Canada.
Once precipitation falls on the ground, whether as rain or snow, it either evaporates, seeps into the soil and flows to aquifers, or forms surface rills, streams, and eventually rivers. The slopes of a river basin concentrate surface runoff to form a river system leading to lakes or the sea (49) (50).
Precipitation that seeps into the ground eventually reaches the zone of saturation where it fills all available pores in soil or porous rock, forming great bodies of groundwater (51). Moving toward areas of lower pressure and elevation, groundwater may eventually discharge into wetlands, springs, lakes, geysers, or coastal waters. Groundwater provides the base flow of many rivers (52).
A river can be divided into three parts (53). The headwaters are characterized by small, steep streams that are fed by rain, snow, glaciers, or springs. Their high-velocity streamflow can carry away large amounts of sediment if the soil of surrounding slopes is not protected by vegetation. Eroded sediments (a problem not restricted to headwaters) represent the major source of pollutants in surface waters (54).
The middle sections of a river are generally less steep. Flowing through comparatively flat land, a river is often surrounded by a floodplain, which is seasonally inundated by runoff from heavy rains or rapid snowmelt. Floodplains can support productive fisheries and agriculture, which depend on nutrient-rich, riverborne sediment. However, periodic floods can cause massive destruction and loss of human life. Human activities also add pollutants--nutrients, pesticides, toxic metals, and toxic organic compounds--to rivers.
Lakes and wetlands are found mainly along the middle and lower reaches of rivers. The water stored in wetlands can recharge groundwater, maintain streamflows during dry periods, and reduce flooding. Wetlands, lakes, and artificial reservoirs often act as sinks for contaminants, which settle with suspended sediments (55). As a river approaches the sea, its freshwater mixes with saltwater. Because of slower currents and changed water chemistry, organic and inorganic matter collected from the runoff of the river basin settles to the bottom. Chapter 12, "Oceans and Coasts," Focus On Coastal Pollution, details the impact of such deposits on estuaries and other coastal waters.
On different continents, humans withdraw 1 to 16 percent of river flows for irrigation, industry, and domestic and municipal use. (See Chapter 22, "Freshwater," Table 22.1.) These withdrawals can have dramatic impacts in particular river systems. Extreme examples of rivers drained dry by withdrawal for irrigation include the Colorado in the United States and the Amu Darya and Syr Darya, which feed the Aral Sea in the Soviet Union (56) (57). Increasing demands are also being made upon groundwater; in the United States, about one half of the drinking water and 40 percent of the irrigation water is drawn from groundwater (58). Overpumping of groundwater by large coastal cities, such as Dakar, Senegal; Jakarta, Indonesia; and Lima, Peru; has led to contamination of underground freshwater by intruding coastal saltwater (59). (See Conditions and Trends, Water Use, above.).
River basins differ greatly in size, climate, topography, geology, vegetation, and land use. Large river basins may contain different mixes of these characteristics, all of which influence the volume and quality of groundwater and surface waters moving through a river basin into the ground, lakes, and coastal waters (60).
In many river basins with extensive vegetative cover, precipitation infiltrates soils and groundwaters, which contribute to steady river flows. Although vegetation causes water loss to the atmosphere through evapotranspiration, it retards the flow of water over land and increases recharge of shallow aquifers (61).
In desert regions with little vegetation, heavy rainfall leads to higher surface runoff rates and flooding. When a river basin is stripped of its natural moisture-holding vegetation by agriculture, deforestation, or urbanization, runoff velocity and erosion increase. Geological conditions--such as soil type--also influence the dynamics of a river basin. For example, permeable soils absorb precipitation more readily, thereby reducing overland flow and runoff volume and velocity.
River basins also differ in the features that determine water flow pattern and chemical composition (62). For instance, floodplains and wetlands store floodwaters and release them slowly, reducing surges in flow following heavy rainfall. According to one study, river basins without wetlands discharge water at five times the rate of basins with 40 percent wetland cover (63). By capturing sediments in stormwater runoff, wetlands and riparian (riverbank) forests also filter nutrients (primarily nitrogen and phosphorus) and other potential pollutants from river water (64). Such buffer zones help maintain river water quality, particularly because most pollutants enter river waters during rapid snow melt or heavy rainfall (65).
With the exception of a few communities in desert and tundra areas, most humans live in river basins (66). Human settlements, industrial development, agriculture, and deforestation have significantly altered the physical and ecological features of many river basins. All of these human activities contribute additional nutrients, metals, and synthetic chemicals to the hydrologic cycle. Table 11.1 describes the major river basin pollutants, their sources, and their effects on aquatic organisms and humans.
Some water pollution comes from diffuse or "nonpoint" sources. For instance, airborne pollutants (from automobiles, factories, and power plants) and waterborne pollutants (from croplands, feed lots, logged forests, and urban areas) can contribute significantly to river basin pollution (67). A 1980 study showed that airborne pollutants in the Potomac River basin account for 70-95 percent of the nitrogen and 20-35 percent of the phosphorus in urban runoff (68). A 1989 study showed that 76 percent of nitrogen, phosphorus, and sediment in U.S. lakes surveyed came from nonpoint sources (69).
Pollutants from diffuse sources may behave differently than those from specific "point" sources, such as sewage treatment facilities and industrial discharge pipes. As contaminants move through aquifers, they form underground plumes that may move slowly toward areas of lower pressure (such as wells) (70). Plumes from point sources tend to be long and narrow but highly contaminated, while plumes from nonpoint sources are large, diffuse, and less contaminated (7l).
Urbanization greatly influences water quantity and quality because of runoff and sewage. Impermeable surfaces such as roofs and highways replace permeable soils and vegetation, increasing the volume, velocity, and temperature of urban runoff, reducing the base flow of rivers during dry periods, raising the temperature of urban streams, and collecting pollutants that range from litter and pet droppings to toxics from atmospheric deposition (72) (73) (74).
Inadequately treated sewage from human settlements introduces large quantities of nutrients, pathogens, heavy metals, and synthetic organic chemicals into surface waters. In industrial countries, much of the sewage generated in urban areas is collected by sewer systems and treated to varying degrees before being discharged into rivers, lakes, or coastal waters. (See Table 11.2.). Primary (physical) and secondary (biological) treatment of sewage may remove 35 and 85 percent of pollutants in sewage, respectively (75), but
they remove only 30 percent of the phosphorus, 50 percent of the nitrogen, and 70 percent of the most toxic compounds. Advanced sewage treatment plants that can further reduce specific pollutant levels cost twice as much to build and four times as much to operate as secondary treatment plants (76). Without regular maintenance and proper operation, primary, secondary, and advanced sewage treatment plants will operate well below their intended standards.
Conventional treatment of sewage does not eliminate the problem of pathogens in sewage. To eliminate human pathogens, the water discharged from sewage treatment plants is sometimes treated with chlorine, which reacts with organic chemicals to form carcinogenic chlorinated hydrocarbons. The sludge produced by sewage treatment can also pollute water, unless it is further treated and incinerated or properly applied to land (77). Finally, where cities combine their sewer systems with storm drainage systems, storm water may overwhelm storm drainage systems and flow into sewer systems, mixing with sewage and discharging into the receiving river, lake, or coastal water body. Some cities have built storm water retaining basins to prevent such discharges (78).
The situation is much worse in the developing world, where more than 95 percent of urban sewage is discharged into surface waters without treatment (79). Many cities in developing countries lack even sewer systems, let alone sewage treatment facilities. For example Bangkok, Thailand--the capital of one of the most economically advanced developing countries--- was considering plans for a sewage system in late 1990. The city relies on four rivers and a series of canals to dispose of an estimated 10,000 metric tons of raw sewage and municipal waste every day (80). Sanitation systems without sewage treatment may actually increase water pollution elsewhere if they merely transfer sewage to rivers and lakes that others use as a water source (81). For many developing countries, bacteria, parasites, and viruses in water supplies remain a more serious threat to human health than toxic contaminants (82). Table 11.3 illustrates the amount of water treatment in certain world regions.
Industry and mining are the principal sources of heavy metals and synthetic organic chemicals in freshwater. Industrial sources of heavy metal pollution include dust from smelting and metal processing; discharge of heavy metal solutions used in plating, galvanizing, and pickling; use of metals and metal compounds in paints, plastics, batteries, and tanning; and leaching from solid waste dumps (83) (84). A 1980 study showed that about 70 percent of anthropogenic heavy metals in the Federal Republic of Germany's Ruhr River came from industrial sources (85).
Heavy metals bioaccumulate at higher levels of the food chain and so pose special risks for people who consume crops grown with, or fish caught in, contaminated waters. More than 600 reported deaths in Japan between 1953 and 1970 were attributed to heavy metal contamination of air, drinking water, fish, and rice (86). Since the 1970s, however, improved wastewater treatment has reduced levels of heavy metals in most major rivers in the industrialized countries (87).
Most synthetic organic chemical pollution comes from industrial sources, including chemical and petrochemical refineries, pharmaceutical manufacturing, iron and steel plants, wood pulp and paper processing, and food processing. Like heavy metals, synthetic organic compounds such as PCBs and certain pesticides concentrate at higher levels of the food chain. Some increase the risk of cancer and reproductive abnormalities in fish, aquatic mammals, and humans. Costs of freshwater pollution from synthetic organics include reduced productivity of fisheries (88), restrictions on consumption of fish from contaminated areas, and contamination of drinking water (89).
In general, industry accounts for a smaller share of freshwater pollution in developing than in developed countries (90). Nevertheless, it poses a serious problem in developing countries because pollution control is often lacking. Such pollution is especially severe in rapidly industrializing regions such as East Asia (9l).
Mining and petroleum extraction pollute freshwater either through discharges of brine or through leaching from mine tailings into groundwater (92). Coal mining and petroleum drilling and refining discharge organic compounds (93). Coal, phosphate, and metal mines pollute freshwater with heavy metals, often at high environmental costs (94). For instance, heavy metals leaching from mine wastes contaminated rice fields in the Ichi River basin in Japan and are correlated with a high incidence of kidney failure. Heavy metal pollution from mines in the Upper Silesia area of Poland wiped out fish in the Szola River (95).
The brine discharged from oil wells (96) or salt and potash mines can also increase the salinity of freshwater bodies. Saline discharges from mines in Germany have made Rhine water unsuitable for greenhouse gardening in the Netherlands (97). Finally, water withdrawal for mine drainage can cause saltwater intrusion into freshwater aquifers (98).
In developing countries, mining can be a greater source of pollution than manufacturing or processing. For instance, mining is a major source of pollution in South America, particularly in the Andes (99).
Agriculture is the leading nonpoint source for water pollutants such as sediments, pesticides, and nutrients, principally nitrogen and phosphorus (100). Increasing demand for food crops has resulted in increased conversion of forests and grasslands into croplands in many countries. One result is greater soil erosion and sedimentation of streams. At the same time, farmers-- especially in some developing countries--have increased production by using larger amounts of fertilizers and pesticides, some of which run off into streams or percolate into groundwater (101). Other agricultural practices, such as frequent plowing and excessive irrigation, can aggravate pollution of freshwater with sediments, salts, and pesticides (102). (See Chapter 7, "Food and Agriculture," Environmental Trends.)
Diversions of water for irrigation can dramatically affect water quality. For example, the Soviet Union's diversion of water from the Amu Darya and Syr Darya (to increase cotton production) has so altered the Aral Sea--once the fourth largest freshwater lake in the world--that even if flows into the sea were to double, the Aral would still shrink to one sixth of its 1960 area, while its salinity would increase to four times that of the oceans (103). All native fish species have disappeared, destroying the local fishing industry (104). (See World Resources 1990-91, Box 10.2, p. 171.)
Transport of agricultural pesticides by surface runoff and leaching into groundwater depends not only on the chemical character and solubility of a pesticide but also on soil properties, agricultural practices, and climatic conditions, particularly precipitation (105). Leaching is greatest where precipitation is high and soils have high permeability but low water-holding capacity. The chemical character of modern pesticides makes them more likely to contaminate groundwater than older pesticides, which leach more slowly through soils (106).
Over the past two decades, livestock farming has intensified, especially in Africa, Asia, and Central and South America. (See World Resources 2990-91, Table 18.3, pp. 282-283.) Grazing livestock remove vegetation, compact soil, and generate large quantities of manure, which affect the quality and quantity of surface runoff (107). Crop-livestock operations pose special risks for freshwater resources when farmers apply excessive amounts of manure and other nutrients to cropland. The problem is especially acute in Europe. (See Chapter 7, "Food and Agriculture," Problems with the Conventional Model.)
The clearest consequence of imprudent logging practices, particularly along streams, is an increase in erosion and sediment loads, with resulting damage to habitats for river organisms and to the water clarity necessary for aquatic plants (108). Debris from logging operations can also increase the input of organic materials, whose decomposition reduces oxygen in river waters. A recent United Nations report cites deforestation as a major cause of changes in runoff, increases in sedimentation, and downstream nutrient enrichment of rivers and lakes worldwide (109).
Deforestation along streams also allows pollutants to wash into rivers and exposes shallow nearshore waters to sunlight, raising water temperatures and fostering oxygen depletion through decomposition of aquatic plants (110). In West and Central Africa, forest clearing for grazing purposes has led to increased streambank erosion, sedimentation of streams, and loss of habitat for a wide variety of stream organisms. Increased sunlight combined with nutrient enrichment in streams has promoted the growth of filamentous algae favored by snails that host the vectors for schistosomiasis (111)
Freshwater polluted by metals and industrial or agricultural chemicals requires expensive, technologically advanced treatment. Preventing pollutants from entering groundwater or surface waters can reduce treatment costs and downstream damage. Some existing, small-scale measures can also salvage nutrients for use in raising food and creating habitat for wildlife.
Conventional sewage treatment is expensive. In the United States, the federal government has provided $57 billion since 1972--as much as 55-75 percent of construction costs, depending on type--for sewage treatment plants (112). The United Nations has estimated that construction costs for treatment plants and submarine outfalls for the 539 Mediterranean coastal towns with populations greater than 10,000 would amount to more than $5 billion (113).
As an alternative to conventional sewage treatment, Arcata, California, a small coastal town of 15,000, has transformed a local garbage dump into 63 hectares of wetlands that serve as a simple, low-cost waste treatment plant. Sewage is collected in sewers, held in ponds where solids settle out, then released into marshes, where it is filtered and cleansed by natural processes. Some of the treated water irrigates other wetlands, the rest is pumped into the bay, where oysterbeds thrive (114).
This approach requires more land than conventional sewage treatment plants. Its cost-effectiveness depends on whether the land would produce greater value from another use, such as agriculture. One Swedish study concluded that the benefits of sewage treatment are greater than the costs of lost agricultural production on the same land (115).
In other areas of the world, partially treated sewage is used to raise fish. For example, a small fraction of the sewage generated by the 7 million inhabitants of Lima, Peru, is directed into holding ponds, where solids settle out and bacteria decompose many of the wastes. After 20-30 days, the water is clean enough to irrigate grain crops for cattle and to raise fish (116). A 1985 study for the World Bank described similar aquaculture operations relying on human excreta in Bangladesh, China, the Federal Republic of Germany, Hungary, India, Indonesia, Israel, Malaysia, Taiwan, Thailand, and Viet Nam (117).
The largest single waste-fed aquaculture system in the world is the Calcutta sewage system, where water and sewage are fed into two lakes covering an estimated 2,500 hectares. After an initial bloom of algae, fish--principally carp and tilapia--are introduced, and additional sewage is fed into the lakes once each month. The system supplies about 7,000 metric tons of fish annually to the Calcutta market, or 2.8 metric tons per hectare per year (118).
Several measures can virtually eliminate human health concerns about fish from sewage-fed fish ponds, such as detaining sewage in stabilization ponds for at least 20 days before introducing it into fish ponds, or transferring fish and shellfish to clean water before harvesting (119).
Tighter government regulation has increased the costs of traditional "end-of-pipe" waste management, such as cleaning up spills and dumps, landfilling, incineration, and off-site recycling (120). In the United States, private business spending on pollution control and waste management increased from $28 billion in 1972 to $47 billion in 1988 (in constant dollars) (121) (122). As a result, industry has sought to reduce the amount of waste it generates in the first place.
Waste reduction is a broad management approach using a variety of technologies. It cuts the volume and toxicity of wastes by recycling them or by redesigning processes and products (123). Companies that undertake waste-reduction programs often save money by using materials and energy more efficiently or by reducing the costs of conventional pollution control and waste disposal (124). Waste reduction has been most successful for process industries such as manufacturing and chemicals. The approach does not work as well in mining or in such high-temperature operations as burning fossil fuels, smelting, and cement production.
The Institute for Local Self-Reliance in Washington, D.C., has documented a variety of waste reduction schemes that significantly reduce production of hazardous materials and water pollution:
According to INFORM, a New York-based environmental research organization, waste reduction probably offers the greatest potential for environmental benefit of any waste management strategy. Preliminary data show that 29 chemical manufacturers, implementing 181 individual waste reduction actions, reduced targeted waste streams by an average of 71 percent (measured by weight) at an average annual savings of $351,000 per action (128). Despite such savings, factory managers often neglect waste reduction because environmental regulations encourage them to focus on disposal or because other investments yield marginally higher returns (129) (130).
The diffuse nature of runoff requires an emphasis on land management throughout a river basin. A variety of techniques can be used to reduce runoff pollution, including soil-conserving agricultural practices, forestry road management, land surface roughening, sedimentation traps, bank stabilization, and redesigned streets (131).
In the last two decades, several practices--including small-scale detention ponds, infiltration basins, porous pavements, and vegetative strips--have been developed that can reduce urban inputs of pollutants by up to 80 percent. Most of these practices enhance pollutant removal by detaining storm waters or enabling them to infiltrate the ground (132).
The effectiveness of these techniques depends on the mechanism used, the fraction of annual runoff that is effectively treated, and the nature of the pollutant being removed (133). Settling ponds, for instance, can be almost completely effective in removing pollutants bound to sediments, but they generally remove less than half of soluble nutrients. Biological mechanisms, such as uptake by bacteria or plants can remove more soluble nutrients. With proper planning, many techniques can also provide important wildlife habitat, groundwater recharge, and recreational benefits (134). Some techniques, such as retaining ponds, may increase downstream water temperatures, whereas others, such as infiltration systems, have little effect on temperature (135).
In the last 20 years, agricultural management practices have been developed to reduce runoff containing nutrients and pesticides that pollute groundwater and surface waters. Such practices include conservation tillage, crop rotation, contour planting, planting cover crops in winter, filter systems, terrace systems, and fertilizer management. These practices control sediment erosion and remove up to 60 percent of the nitrogen and phosphorous available for runoff from croplands.
One study estimated that conservation tillage alone can reduce phosphorus loads to surface waters by 30 percent, although nitrogen is unaffected (136). In combination, these practices are even more effective. They can also reduce pesticide runoff, although their effect on migration of pesticides to groundwater is undetermined (137). (See Chapter 7, "Food and Agriculture," Box 7.2.)
Other new mechanisms for reducing agricultural pollution include increasing taxes and fees on inputs such as pesticides, fertilizers, and irrigation water; incentives to leave highly erodible land uncultivated; and the removal of production subsidies. (See Chapter 7, "Food and Agriculture," New Policy Options.)
Practices such as pond construction and permanent vegetation improvement can reduce nitrogen and phosphorus runoff from pasturelands by up to 60 percent (138). Limited use of such practices in the Potomac River basin in the United States has yielded runoff reductions of 7 percent in nitrogen and phosphorus (139). Management of manure through proper storage and application can substantially reduce nutrient runoff and the need for commercial fertilizers. Treatment lagoons and ponds can reduce the amount of nutrients in animal wastes before they are applied to fields (140).
In the Netherlands, the size and number of livestock farms are being reduced, and regional centers are being established to store surplus manure during periods when spreading these nutrients on agricultural lands would lead to runoff or leaching (141). Dairy farms near the Everglades in the United States are now required to reduce the flow of nutrients from their feed lots by using wastewater to irrigate pastures (142).
Protecting forested areas along the headwaters of a river is central to protecting the water quality of the entire river (143). Locating roads across rather than up and down slopes, allowing drainage to flow through culverts beneath roads, and locating activities away from streams can significantly reduce runoff and sedimentation from logging operations. Leaving forested buffers along streams can filter out sediments and nutrients eroded from deforested areas and reduce streambank erosion (144).
Effective water management requires a broad plan for an entire river basin (145). This is particularly challenging where a river basin is under the jurisdiction of several nations. Worldwide, 214 river or lake basins, populated by 40 percent of the world's human population and covering more than 50 percent of the Earth's land area, are shared by two or more countries (146) (147). Competition for groundwater also contributes to international tensions, especially in the Middle East (148). (See Table 11.4.).
International law regarding shared freshwater resources gives little guidance in international river basin management. For instance, current international law limits the responsibility of upstream nations to ensuring that their activities do not conflict with the rights of downstream nations (149). As a result, most downstream countries do not pursue their rights through international courts, but through diplomacy (150). The United Nations has attempted to provide guidance in this area. (See Box 11.2.)
By 1971, 286 international treaties concerning water resources had been negotiated. More than two thirds of them concerned river basins in Europe and North America, and most sought coordinated surveys and planning or regulation of navigation (151). Some of the more recent efforts involve control of land-based sources of pollution. In February 1991, for instance, the Economic Commission for Europe adopted a convention addressing the prevention, control, and reduction of transboundary pollution that could have an important effect on water resources (152). Countries sharing river basins flowing into the North Sea are cooperating to reduce contamination of marine waters by reducing contamination of freshwater.
One of the few examples of international efforts to reduce pollutants in an international river basin is a series of treaties concerning the Rhine River, the basin of which covers 225,000 square kilometers and includes eight countries (153). These treaties have had both encouraging success and spectacular failure.
At the insistence of the Netherlands, which was concerned about increased salinity in the Rhine, France, the Federal Republic of Germany, Luxembourg, the Netherlands, and Switzerland began discussing arrangements for reducing pollution in the 1950s, and formed the International Commission for the Protection of the Rhine against Pollution (ICPRP) in 1963. A technical commission, charged with monitoring pollutants, the ICPRP at first achieved few concrete results. However, to stem increasing pollution from industrial and municipal sources, the parties to the ICPRP signed the Convention for the Protection of the Rhine Against Chemical Pollution in 1976 (154) (155). In December 1986, they agreed to the Rhine Action Programme, which seeks to produce drinkable water from the Rhine, reduce sediment pollution, and restore the Rhine environment so that indigenous aquatic life returns. To this end, the parties agreed to a 50-percent reduction (from 1985 levels) in the discharge of 30 priority pollutants into the river by 1995 (156). The Netherlands, the Federal Republic of Germany, France, and Switzerland agreed to share abatement costs of $136 million (157). And in the summer of 1991, the German chemical industry federation agreed to reduce the flow of toxic chemicals into the Rhine (158). These international efforts, combined with domestic pollution controls, have produced measurable benefits: since the early 1970s, concentrations of heavy metals have fallen and biological treatment of organic waste has reduced oxygen depletion and fish kills (159) (160).
These encouraging results must be measured against a spectacular and nearly catastrophic failure. The Convention for the Protection of the Rhine Against Chemical Pollution includes provisions for an international warning system that is triggered by sudden and sizable increases in pollutants. The warning system failed in November 1986, when efforts to extinguish a fire in a chemical warehouse in Basel, Switzerland, released unknown quantities of a potpourri of chemicals including organophosphates, organic mercury compounds, and various agrochemicals. Swiss authorities may have violated the Conventions' warning provisions by not informing the other parties about the release of pollutants. If winter ice had covered the river and concealed the fish killed by the toxic chemicals, withdrawals from the river for drinking water might well have continued--with catastrophic consequences. The Rhine conventions did not provide citizens downstream from the accident with a clear basis for pursuing damages against the chemical plant or Swiss authorities (16l).
So far, international agreements have failed to control some key pollutants; for example, concentrations of nitrates, mostly of agricultural origin, continue to rise; and groundwater in Germany is increasingly contaminated with nitrates and pesticides. Salmon, at the top of the food chain and therefore a key indicator of river health, have disappeared completely from the Rhine. And although chlorides were one of the pollutants originally targeted for control by the ICPRP, only one country, France, has reduced discharges (162).
Cooperation among states and nations is usually necessary to manage watershed pollution, but upstream nations or states have little incentive to curb their pollution when they can simply pass the damage on to their downstream neighbors. The case studies in Chapter 12, "Oceans and Coasts," suggest that regional agreements have the best chance of success when there is a mediating body, a history of cooperation, a scientific basis for action--and when all parties benefit from cleaner water. When upstream polluters can see no benefit from the expense of curbing their pollution, negotiations are especially difficult.
Even within a nation, where a central government can provide economic incentives or impose regulations to protect downstream interests, there are few examples of effective watershed management. Most industrialized nations have applied discharge regulations to industrial polluters and have helped finance municipal sewage systems. Controls on runoff pollution are just emerging, however, and very little has been done to hold upstream polluters, such as farming and logging interests, responsible for downstream loss of water quality, fisheries, and habitat. A watershed "polluter pays" management scheme might involve policy tools such as regulations, penalties, compensation, or tax incentives to discourage upstream pollution.
20. Organisation for Economic Co-operation and Development (OECD), The State of the Environment (OECD, Paris, 1991), p. 60.
22. Op. cit. 2, p. 163.
23. Op. cit. 2, pp. 162-163.
24. World Health Organization (WHO) and United Nations Ennronment Programme (UNEP), WHO/UNEP Report on Water Quality (WHO and UNEP, Geneva and Nairobi, 1991), pp. 61-63.
37. United Nations Economic and Social Council, "Achievements of the International Drinking Water Supply and Sanitation Decade 1981-90" (United Nations, New York, 1990), pp. 3-6.
38. Ibid7 p. 21.
39. Ibid., pp. 23-24.
40. Preparatory Committee for the United Nations Conference on Environment and Development (PREPCOM), "Protection of the Quality and Supply of Freshwater Resources: Application of Integrated Approaches to the Development, Management and Use of Water Resources" (PREPCOM, Geneva, 1991), pp. 7-9.
41. Ibid., pp. 2-4.
42. Peter A. Kumble, The State of the Anacostia: 1989 Status Report (Metropolitan Washington Council of Govemments, Washington, D.C., 1990), pp. 13-19.
43. Larry Master, "Aquatic Animals: Endangerment Alert," Nature Conservancy (March/April 1991), pp. 26-27.
44. Organisation for Economic Co-operation and Development (OECD), Water Pollution by Fertilizers and Pesticides (OECD, Paris, 1986), p. 65.
45. Timothy R. Henderson, ''The Institutional Framework for Protecting Groundwater in the United States," in Planning for Groundwater Protection, G. William Page, ed. (Academic Press, San Diego, California, 1987), pp. 29-30.
46. Op. cit. 42, pp. 21-22.
47. Op. cit. 40, pp. 11-13.
48. M. Marchand and F.H. Toornstra, Ecological Guidelines for RiDer Basin Develovment (translated from Dutch) (Commission on Ecology and Development Cooperation, Leiden, the Netherlands, 1986), p. 1.
49. Op. cit. 2, pp. 167:168.
50. Peter Rogers, Peter Lydon and David Seckler, Eastern Waters Study: Strategies to Manage Flood and Drought in the Ganges-Brahmaputra Basin, prepared for U.S. Agency for International Development, (Irrigation Support Project for Asia and the Near East, Arlington, Virginia, 1989), pp. 9 and 12.
51. Op. cit. 1, pp. 232-234.
52. Op. cit. 1, pp. 232-234.
53. Op. cit. 48, p.4.
54. A.J. Bowie and C.K Mutchler, "Sediment Sources and Yields from Complex Watersheds," in Proceedings of the Third International Symposium on River Sedimentation, S.Y. Wang, H.W. Shen and L.Z Ding, eds. (University of Mississippi, University, Mississippi, 1986), p. 1223.
55. Op. cit. 1, p. 250.
56. John D. Milliman, "Fluvial Sediment in Coastal Seas: Flux and Fate," Nature and Resources, Vol. 26, No. 4 (Parthenon, Park Ridge, New Jersey, 1990), p. 16.
57. Op. cit. 2, p. 171.
58. Op. cit. 1, p. 240.
59. Martine Allard, GEMS/Water Co-ordinator, National Water Institute, Burlington, Ontario, Canada, 1991 (personal communication).
60. P.G. Waldo, "Sediment Yields from Large Watersheds," in Third International Symposium on River Sedimentation (University of Mississippi, University, Mississippi, 1986), p. 1241.
61. Op. cit. 2, p. 168.
62. Op. cit. 48, pp. 12-14.
63. G. Noble and W. Wolff, "The Ecological Importance of Wetlands," paper presented at the Conference of the Contracting Parties of the Convention on Wetlands of International Importance Especially as Waterfowl Habitat, Goningen, May 1984, cited in M. Marchand and F.H. Toornstra, Ecological Guidelines for River Basin Development (translated from Dutch) (Commission for Ecology and Development Cooperation, Leiden, the Netherlands, 1986), p. 12.
64. Mark K. Mitchell and William B. Stapp, Field Manual for Water Quality Monitoring: An Environmental Education Program for Schools, 4th ed.(Thomson-Shores, Dexter, Michigan, 1990), p. 153.
65. Robert C. Petersen, Jr., Bent Lauge Madsen, Margaret A. Wilzbach, et al., "Stream Management: Emerging Global Similarities," Ambio, Vol. 16, No. 4 (1987), p. 16.
66. Op. cit. 2, p.16.
67. Op. cit. 1, pp. 248-249.
68. Jon Lugbill, Potomac River Basin Nutrient Inventory (Metropolitan Washington Council of Governments, Washington, D.C., 1987), p. 141.
69. U.S. Environmental Protection Agency (EPA), Report to Congress: Water Quality of the Nation's Lakes (EPA, Washington, D.C., 1989), p. 12.
70. Op. cit. 1, pp. 233-234.
71. David Moody, Chief, Office of Water Summary, U.S. Geological Survey, Washington, D.C., 1991 (personal communication).
72. Op. cit. 64, pp. 47 and 149.
73. Bruce Newton, Chief, Watershed Branch, U.S. Environmental Protection Agency, Washington, D.C., 1991 (personal communication).
74. "Urbanization lncreases Temperatures in Small Headwater Streams According to COG Study," Waterline, Vol. 2, No. 3 (Metropolitan Washington Council of Governments, Washington, D.C., Winter 1991), pp. 4-5.
75. Op. cit. 69, p.15.
76. Op. cit. 1, p. 260.
77. Op. cit. 1, p. 261.
78. Op. cit. 64, p. 33.
79. Op. cit. 40, p. 3.
80. Don Hinrichsen, Our Common Seas: Coasts in Crisis, (EarthScan Publications, London, in association with the United Nations Environment Programme, Nairobi, 1990), p. 108.
81. Op.cit. 2, p.69.
82. G. William Page, "Drinking Water and Health," in Planning for Groundwater Protection, G. William Page, ed. (Academic Press, San Diego, California, 1987), p. 69.
83. Michel Meybeck, Deborah V. Chapman and Richard Helmer, eds., Global Environment Monitoring System: Global Freshwater Quality, A First Assessment (Basil Blackwell Ltd., Oxford, U.K, 1989), p. 160.
84. Rodney Sobin, Research Assistant, World Resources Institute, Washington, D.C., 1991 (personal communication).
85. Op. cit. 82, p. 161.
86. Op. cit. 82, p. 159.
87. Organisation for Economic Co-operation and Development (OECD), OECD Environmental Data Compendium 1991 (OECD, Paris 1991), Data Supplement, Tables 3.3 D and E, pp. 60-63.
88. Op. cit. 2, p. 186.
89. Op. cit. 83.
90. Op. cit. 82, p. 12.
91. Op. cit. 40, p. 3.
92. Op. cit. 82, p. 282.
93. Op. cit. 82, pp. 182-183.
94. Op. cit. 82, p. 144.
95. Op. cit. 82, p. 162-163.
96. Op. cit. 82, p. 145.
97. Op. cit. 82, p. 283.
98. Op. cit. 82, p. 144.
99. Op. cit. 40, p. 3.
100. Op. cit. 1, p. 25.
101. Op. cit. 44, pp. 30-31, 33, and 131.
102. Op. cit. 44, pp. 25-26.
103. Kenneth D. Frederick, "The Disappearing Aral Sea," Resources, No. 102 (Winter 1991), p. 11.
104. Op. cit. 1, p. 242.
105. Robert F. Carsel and Charles N. Smith, "Impact of Pesticides on Ground Water Contamination," in Silent Spring Revisited, Gino J. Marco, Robert M. Hollingworth, and Williarn Durham, eds. (American Chemical Society, Washington, D.C., 1987), p. 74.
106. Ibid., p. 76.
107. Op. cit. 44, pp. 100-101.
108. R.L. Welcomme, River Basins (Food and Agriculture Organization of the United Nations, Rome, 1983), p. 38.
109. Op. cit. 40, pp. 2-3.
110. Op. cit. 106, p. 38.
111. Op. cit. 65, p. 171-172.
112. Martin R Lee, John Blodgett, Claudia Copeland, et al., Summaries of EnDironmenhl Imos Administered by the Environmental Protection Agency (Congressional Research Service, Washington, D.C., 1991), p. 34.
113. Michel Grenon and Michel Batisse, eds., Futures for the Mediterranean Basin: The Blue Plan (Oxford University Press, Oxford, U.K., 1989), p. 255.
114. Op. cit. 1, p. 263.
115. Op. cit. 65, pp. 171-172.
116. Op.cit. 1, p.26.
117. Peter Edwards, Aquaculture: A Component of Low Cost Sanitation Technology (The World Bank, Washington, D.C., 1985), pp. 3-14.
118. Ibid., pp. 7-9.
119. Ibid., pp. 37-42.
120. John Elkington and Jonathan Shopley, Cleaning Up: U.S. Waste Management Technology and Third World Development (World Resources Institute, Washington, D.C., 1989), p. 7.
121. Kit D. Farber and Gary L. Rutledge, "Pollution Abatement and Control Expenditures: Revised Estirnates for 1972-83, Estimates for 1984," Survey of Current Business, Vol. 66, No. 7 (U.S. Department of Commerce, Bureau of Economic Analysis, Washington, D.C ), July 1986, p. 97.
122. David M. Bratton and Gary L. Rutledge "Pollution Abatement and Control Expenditures, 1985-1988," Survey of Current Business, Vol. 70, No. 11, (U.S. Department of Commerce, Bureau of Economic Analysis, Washington, D.C., November, 1990), p. 34.
123. Op. cit. 118, p. 14.
124. George Heaton, Robert Repetto, and Rodney Sobin, Transforming Technology: An Agenda for Environmentally Sustainable Growth in the 21st Century (World Resources Institute, Washington, D.C., 1991), p. 17.
125. Larry Martin, Proven Profits from Pollution Prevention: Volume II (Institute for Local Self Reliance, Washington, D.C., 1989), pp. 87-89.
126. Ibid., pp. 65-69.
127. Ibid., pp. 41-43.
128. Warren R. Muir, "Testimony Before the United States Senate Committee on Environment and Public Works, Subcommittee on Environmental Protection, on the Toxic Use and Source Reduction Provisions of 5.976, The Resource Conservation and Recovery Act Amendments of 1991" (INFORM, New York, July 24, 1991), pp. 3 and 5.
129. Mark Dorfman, Associate Program Director, INFORM, New York, 1991 (personal communication).
130. Larry Martin, United Nations Conference on Environment and Development Liaison,
The Other Economic Summit, Washington, D.C., 1991 (personal communication).
131. Op. cit. 69, p.16.
132. Thomas R. Schueler, Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban BMPs (Metropolitan Washington Council of Governments, Washington, D.C., 1987), figure 2.4, p. 2.13.
133. Ibid., p. 2.11.
134. Ibid., p. 2.12.
136. Op. cit. 68, p. 47 and Table 4.8, p. 50.
137. Op. cit. 104, p. 81.
138. Op. cit. 68, p.77.
139. Op. cit. 68, p. 85.
140. Op. cit. 68, p. 94-
141. Op. cit. 65, p. 170.
142. Keith Schneider, "Returning Part of Everglades to Nature for $700 Million," New York Times (March 11,1991), p. B10.
143. Op. cit. 65, p. 172.
144. Op. at. 68, p. 128.
145. B.M. Abbas, "River Basin Development: Keynote Address," in Proceedings of the National Symposium on River Basin Development, Munir Zaman, ed. (Tycooly International, Dublin, 1983), p. 6.
146. Jerome Delli Priscoli, "Epilogue," Water International, Vol. 15, No. 4 (International Water Resources Association, Urbana, Illinois, 1990), p. 236.
147, Asit K. Biswas, "Some Major Issues in River Basin Management for Developnng Countries," in Proceedings of the National Symposium on River Basin Development, Munir Zaman, ed. (Tycooly International, Dublin, 1983), p. 22
148. Op. at. 31, p. 17,
149. Andrew H. Darrell, "Killing the Rhine: Immoral, But Is It Illegal?" Virginia Journal of International Law, Vol. 29, No. 2 (1989), pp.441-447.
150. Ibid., p. 449.
151. Margaret S. Petersen, Water Resource Planning and Development (Prentice-Hall, Englewood Cliffs, New Jersey, 1984), p. 164.
152. United Nations (U.N.), "Convention on Environmental Impact Assessment in a Transboundary Context" (U.N., Espoo, Finland, 1991), p. 2.
153. John Bartholomew and Son, Times Atlas of the World, 7th ed. (Times Books, London, 1988), p. xiv.
154. Alexander Kiss, "The Protection of the Rhine Against Pollution," Natural Resources Journal, Vol. 25, No. 3 (University of Mexico School of Law, Albuquerque, New Mexico, 1985), pp. 621-625.
155. A. Volker, "Integrated Development of the Delta and Upland Portions of a River Basin," in Proceedings of the National Symposium on River Basin Development, Munir Zaman, ed. (Tycooly International, Dublin, 1983), pp. 47-50.
156. J. de Jong, "Management of the River Rhine," Water Environment and Technology, Vol. 2, No. 4, (Apnl 1990), pp. 50-51.
157. Peter H. Sand, Lessons Learned in Global Environmental Governance (World Resources Institute, Washington, D.C., 1990), p. 8.
159. Op. cit. 154, p. 46.
160. Richard L. Holman, "International World Wire: Protection Pact for the Rhine," Wall Street Journal (August 22,1991), p. A7.
161. Op. cit. 147, pp. 422 and 453.
162. Op. at. 154, pp. 46, 49, and 50.