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ACHIEVING ECO-NOMIC SECURITY* By Jim Bell CHAPTER
IX ECO-NOMIC SECURITY AND WATER Efficient Water Use In
Agriculture Strategies for Increasing
Water Security Efficient Water Use In
The Residential Sector Community Scale Water
Recycling Climate Appropriate
Landscaping Efficient Water Use In
Industry Efficient Water Use:
Other Benefits Watershed Friendly
Agricultural Practices Watershed Function And
Forestry Forestry And
True-Cost-Pricing Land Development And
Watershed Function Protecting Watersheds
from Pollution Avoiding Pollution In
And Around Our Homes Watershed Pollution And
Agriculture Using Organic
Agriculture To Avoid Watershed Pollution Watershed Pollution From
Business And Industry Some Good Efforts To
Reduce the Production And Use Of Toxic Materials The Economic Impact Of
Environmental Protection Efficiency and Renewable
Energy: Developing A Watershed Friendly Energy Plan Protecting Groundwater
From Pollution Improving Water
Infrastructure Security Strategies For Reducing
The Problem Of Siltation Improving The Eco-nomic
Security Of Water Infrastructures Quick Fixes Verses A
Whole System Approach |
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Synopsis Our water security, the availability of clean water in sufficient quantities to meet our needs, is decreasing. This decrease in our water security is caused by human activities which are contaminating our surface and groundwater. Human activities are also damaging the ability of our watersheds to recharge our groundwater systems. All these problems can be corrected. And though it is not widely recognized, all the technological know-how needed to make these corrections already exists and is in use in various locations on our planet. |
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Until our sun burns out some 5 billion years from now, water on our planet is infinitely recyclable. Unlike oxygen which depends on plant life for renewal, the hydrological cycle needs only the evaporative energy of the sun to set it in motion. Changed into a gas through the absorption of solar energy, water vapor is transported by the wind throughout the atmosphere. Here it condenses as rain, fog, snow, or dew and returns to replenish the earth's land, waterways, and groundwater storage basins. Even though the amount of water on our planet has not diminished, our water security (the availability of clean water in sufficient quantities to meet our needs) is certainly decreasing. This decrease in water security is primarily caused by human activities which are:
Although the present situation is becoming increasingly serious, there are a number of things we can do to reverse this trend. |
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One way to increase water security is to use water more efficiently. By using water efficiently we reduce the drain on surface and groundwater supplies and the need to build or expand costly and ecologically damaging water storage and delivery systems. Efficient water use will also reduce the per capita cost of wastewater treatment. With more water efficient toilets and showerheads less sewage is generated per person. Efficient water use does not mean doing without the productivity, usefulness, and enjoyment that the use of water can bring. It does not mean taking fewer or shorter showers or flushing toilets less often. It does mean using better technologies like low-flow showerheads and water efficient toilets. Efficient water use also means that we can have luxuriant landscapes and productive agriculture by growing plants that are adaptable to local climates and by using water efficient irrigation technologies and strategies where irrigation is required. Investing in water efficiency also makes good economic sense. The payback, or time needed to save enough money on reduced water purchases to pay for the cost of water saving equipment, is almost always less than 5 years and often less than two years. (390) These paybacks would be considerably shorter )if government subsidies which keep water prices artificially low were removed. If the true eco-nomic costs associated with damming rivers, building and maintaining aqueducts, depleting aquifers, using energy for pumping, and wastewater treatment were included in the accounting, the payback on saving water through efficiency would be close to instantaneous. (391) Just in the arena of energy, "California's vast State Water Project uses almost as much electricity to pump water around the state as all the people of Los Angeles use". (392) California farmers that
benefit from the federally subsidized Central Valley Project (CVP) "have
repaid only 5 percent of the project's cost over the last 40 years, with the
total subsidy exceeding $930 million." (393)
Additional subsidies came in the form of "at least $200
million in water subsidies" that were given to farmers by the Bureau of
Reclamation "in 1986 to grow crops that the Department of Agriculture was
paying other farmers not to grow because of surpluses." (394) Such subsidy-loaded policies have been resistant to change, and even when changes occur they tend to be incremental. Recently, the government raised one of its irrigation district water costs from $3.50 to $14.95 per acre foot when the district's contract came up for renewal. While this represents a 400 percent price increase, it is "still only 28 percent of the water's true cost." (395) Even this 28 percent figure is misleading since it only includes costs like building and maintaining dams and aqueducts and the cost of moving the water around. It does not include the ecological and social costs associated with our present water policies. If these costs were included in the analysis, the subsidies taxpayers are paying to keep the present systems going would loom even larger. In all, "the government (taxpayers) is spending more than $534 million a year to provide cheap irrigation water to western farms, many of which in turn are producing surplus crops that reap additional federal farm subsidy payments, according to a new Interior Department report." (396) |
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To maximize water security, it is important to use water efficiently in every way we can. But more efficient water use in agriculture could save more water than all other efficiency measures combined. Worldwide the amount of water used in agriculture "accounts for some 70% of global water use", greatly exceeding the quantity of water used for domestic and commercial purposes. (397) In countries like the U.S. that have well-developed irrigation infrastructures, up to eighty-five percent of all water used is consumed by agriculture. (398) One of the most troubling aspects of this water use in agriculture is how rapidly it is depleting groundwater supplies. In 1986 the U.S. Department of Agriculture reported "that one-fourth of the 21 million hectares (52 million acres) of U.S. irrigated cropland was being watered by pulling down water tables anywhere from six inches to four feet per year." (399) The depletion of water tables because of crop irrigation is also a problem in countries like China and India. (400) |
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Whether in the United States or abroad, much of the water used by agriculture can be saved through the use of efficient irrigation practices and by growing climate appropriate crops. The most prevalent form of irrigation in the world today is to periodically flood fields with water. This form of irrigation is inexpensive to establish where land is flat but it is not particularly efficient. (401) This is because a large percentage of water often runs off a field before it has time to soak into the soil. In poro)us soils substantial quantities of water can be lost because it percolates to underground levels beyond the reach of plant roots. (402) If this water returns to the aquifer from which it was extracted, this can be positive but not if the water becomes contaminated with pesticides and chemical fertilizers along the way. Sprinkler systems are generally more water efficient than flooding because the amount of water applied and the evenness of its distribution is more easily regulated. (403) On the negative side, sprinkler systems are expensive to install and maintain. Sprinkler systems also increase the amount of water lost to evaporation. Water evaporation is increased as it is dispersed in small droplets through the air and as water sits on plant foliage. Such losses can be avoided to a large extent if sprinklers are used at night when the humidity is usually higher than it is during the day. The efficiency of large
sprinkler systems can also be enhanced by attaching "drop tubes" to
sprinkler arms. "Called low-energy precision application (LEPA), these systems
deliver water closer to the ground and in large droplets, cutting evaporation
losses." (404) The efficiency of flooding and sprinkler systems can be improved
if fields are precisely leveled. Laser technology can be used to guide farm
equipment to insure accurate leveling. (405)
Drip irrigation, a technology developed in the 1960s in Israel, is a further advancement in the efficient use of water for growing plants. This method delivers water directly to each plant by means of small tubes that supply just enough water to saturate plant root zones. (406) Other drip technologies include soaker hoses and various specialized emitters suitable for different crops. Soaker hoses, for example, are good for many row crops because they weep water along their whole length. Drip irrigation devices can be used on the surface, on the surface below mulch, or below the surface depending on plant requirements. Losses to evaporation can be almost completely eliminated when emitters are installed below mulch or beneath the soil surface. While drip equipment is
relatively costly, increased crop yields coupled with money saved by reducing
water consumption can result in a quick payback on the investment. In Israel,
where drip systems are used to "supply water and fertilizer directly
onto or below the soil...experiments in the Negev Desert have shown . . .
yield increases of 80 percent over sprinkler systems." (407) Computer technologies are also being mobilized to increase water use efficiency in agriculture. One devise called a tensiometer, measures the moisture content of the soil and the amount of moisture in the soil that is actually available to plants. (408) This second feature is important because some soils, like those with a high clay content, are so absorptive that they do not give up the water they hold easily to plants. Sandy soils, on they other hand, do not hold water like clay soils. They may have a relatively low moisture content but almost all the moisture in a sandy soil is available to plants. When tensiometers sense that the moisture content of a particular soil is too low to meet plant needs, they activate an automated irrigation system. Tensiometers can also be read manually for more low tech applications. Automated irrigation systems can be programmed so that irrigation water is only applied at night to minimize the loss of irrigation water to evaporation. Automated systems can also be designed to detect leaks, compensate for wind speed, control the application of fertilizer, and optimize the effect of the fertilizer used. Though they are costly to install, such "systems typically pay for themselves within 3 to 5 years through water and energy savings (using less water means that less energy is needed for pumping) and higher crop yields." (409) A new development in the efficient water use arsenal is to combine water efficient technologies with weather monitoring programs. The University of Nebraska's Institute of Agriculture and Natural Resources has developed a computer program called "IRRIGATE" that compiles information gathered across the state of Nebraska from small weather stations. By calling a telephone hot line, farmers can "find out the amount of water used by their crops the preceding week, and then adjust their scheduled irrigation dates accordingly." (410) The California Department of Water Resources is involved in a similar program. The California Irrigation Management System (CIMIS) that is aiming to save 740 million cubic meters of water annually by the year 2010. (411) (740 million cubic meters equals a little more than 600,000 acre feet or about the same amount of water used in 1990 by the 2.4 million people living in San Diego County, California, USA.) Like Nebraska and California, Wisconsin has developed its own system of weather monitoring to assist farmers. This system, which is called the Wisconsin Irrigation Scheduling Program (WISP), is managed by irrigation specialists through the University of Wisconsin. (412) |
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Efficient water use in agriculture can also be improved by minimizing the practice of growing water intensive crops in climate zones that have little rainfall and high rates of evaporation. With water efficient cropping, the water requirements of a particular crop should be reasonably close to the natural precipitation that could be expected in the climate zone where it is grown. Irrigation for such crops would be relegated to evening out yearly rainfall totals and as a way to supply water during periods when rainfall is below normal. To date, research in the development and use of low water use crops has been poorly funded. "Perhaps 15% of the $82-millon University of California budget for agricultural research is spent on water conservation, but mostly to improve existing crops." (413) Nevertheless, there are a number of promising plants now being grown, some commercially and others experimentally. Sweet sorghum, for example, is already widely grown. It requires a third less water and half the fertilizer required by corn to produce a crop and sweet sorghum is an excellent animal food. Currently, most of the corn grown in the U.S. is used for animal feed. (414) According to Steve Staffer, an alternative crop expert with the California Department of Agriculture, sweet sorghum can also outperform corn as an energy crop. An acre of corn can be processed into 360 gallons of ethanol. Processing an acre of sorghum can produce 600 gallons. Staffer estimates that by growing low water use plants like sorghum, "California could produce 25% to 30% of its energy needs, without affecting our price of food". (415) Given Staffer's projections, producing ethanol from sorghum alone could more than supply all the energy needed in California today if the efficiency measures described earlier were in place. Other promising low water use crops include:
While the strategy discussed above may seem obvious, farmers who benefit from federal subsidies, which allow them to purchase water at rates as low as 1/10 the price that urban dwellers pay, have little incentive to grow things that make more sense in the desert. (417) |
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In his book Cadillac Desert, Marc Reisner points out such subsidies lead us into absurd situations. In 1986, four low value crops grown in California [pasture (grass and hay), alfalfa, cotton, and rice] consumed 5.3, 3.9, 3.0, and 2.0 million acre feet of water respectively. Added up, this is almost three times as much water as was consumed by the 27 million people living in California, including all the water they used to irrigate landscapes and keep their swimming pools full. (418) Even if all these low value crops were totally discontinued and no more water efficient crops were grown in their place, the economic loss to the state would be $1.7 billion or less than one third of one percent of the $550 billion California economy. (419) "That $1.7 billion loss of revenue, by the way, is exactly the cost of the proposed Auburn Dam (in northern California) that farmers want taxpayers to build for them. By simply retiring the land we'd get 75 times more water for our money." (420) Additionally, if we converted a little over half the land now used just to grow grass and hay to grapes or other speciality crops with a similar or greater dollar value, the $1.7 billion loss would be erased. (421) Grapes require roughly the same amount of water per acre as grass and hay pasture. This is a perfect example of how the lack of true-cost-pricing promotes practices that are not in anyone's long term interest. This even includes the farmer whose over-irrigated soil is becoming increasingly unproductive as salt and other minerals are concentrated. Another example of Alice in Waterland economics is the proposed Peripheral Canal (also in California). In his book Water and Power, Harry Dennis presents a well documented case that increasing water use efficiency will easily meet the water needs of California, into the foreseeable future, at a considerably lower cost both economically and to the environment. (422) If constructed, the 42 mile long Peripheral Canal and its associated projects would ultimately cost the public $23 billion or in excess of $100,000 per foot to build. (423) An essay by John Burnham, the Metropolitan Water District's only accountant until he retired, argues that even if water was delivered to Southern California by a completed Peripheral Canal, its $1,267 per acre foot cost would be over three times what people would actually pay for most uses. (424) |
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A parallel aspect of growing low water use crops is related to the production of meat. Currently, "Over half the total amount of water consumed in the United States goes to irrigate land growing feed for livestock." (425) To put this fact into perspective, a 50% reduction in the production of livestock nationally would free up almost twice as much water as is currently used in the U.S. domestically, commercially, and by industry combined. (426) Though the production of meat in all its forms is water intensive, growing beef requires the most water. It takes approximately 2,500 gallons of water to produce a pound of beef. (427) Given this 2,500 gallon figure it takes up to 100 times more water to produce a pound of beef as it does to produce a pound of wheat. "Rice takes more water than any other grain, but even rice requires only a tenth as much water per pound of production as meat." (428) |
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Although
residential water use accounts for only about 8% of the water used in the
United States, from an ecological security perspective it is important to use
water more efficiently on every front. Using residential water more
efficiently also makes good economic sense. Even from the business as usual economic perspective a number of municipalities and agencies are getting on the efficiency bandwagon. For example, the city of Glendale Arizona passed an ordinance that gives residents up to a $100 cash rebate for installing low flow toilets (1.6 gallons or less). (429) This is because city leaders realized that rebating the toilets was much less expensive than increasing water supplies and sewer capacity. The California Department of Water Conservation estimates "that installing a low flow toilet can save a family of four $25 to $50 a year on water bills." (430) The producers of Consumer Reports magazine reported an even larger savings potential. "By our own calculations, an average family that uses municipal water can save as much as $50 to $75 per year on water and sewer bills by switching to low-flow showerheads and low-flush toilets." (431) In addition to saving money on water, low flow shower heads and water efficient appliances also save on energy costs. Just changing from a 6 gallon per minute to a 2 gallon per minute showerhead can save over half the energy used in a home to heat water. (432) This can amount to an energy savings of $50 per year. (433) Faucet restrictors, automatic shut off faucets, and water-efficient appliances can also save water and energy. Faucet flow restrictors and automatic shut-off faucets can cut the use of sink water in half while reducing energy consumption for water heating. State-of-the-art washers and dishwashers use only 70 to 75 percent of the water and energy consumed by less efficient models. (434) If all the efficiency measures just described were in general use, household water consumption in the U.S. could be reduced by 60% or more. (435) The use of water in toilets can be eliminated entirely through the use of dry or composting toilets. Composting toilets come in a variety of designs ranging from the old-fashioned outhouse to the modern chambered versions where the composted residues are periodically removed and used as fertilizer. These modern systems usually include a port for adding kitchen scraps which are composted along with toilet wastes. Sawdust or other similar material is added after each use to control odors. (436) Some composting toilets work better than others. Check the following footnote reference for details. (437) |
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Water recycling is another way to improve residential water use efficiency. Water recycling can occur on several levels. Home gray water systems (bath and sink water) may be as simple as draining bath and wash water into one's yard. Depending on the particular situation, more sophisticated systems may involve filtering, pumps, and disinfection. (438) Graywater includes bath, sink, and water from washing clothing. It excludes toilet wastes. Food scraps and many soaps and shampoos present in graywater are not usually a problem since they can be broken down by soil organisms into nutrients that are used by plants. In some states, home gray water recycling is illegal. [Check with local health officials] The reason for this prohibition is that graywater may be contaminated by harmful bacteria, viruses and parasites. Contamination can occur in a number of ways, such as washing diapers at temperatures too low to kill harmful organisms, or from the small amounts of fecal material that is washed off our bodies when we bathe. For this reason, gray water that has not been disinfected should not be used to directly water vegetable parts that are to be eaten or on lawn areas where direct human contact is likely. Although the use of graywater could be potentially harmful, "it's worth noting that health officials we consulted knew of no documented case of illness caused by gray-water use." (439) Since there is a small possibility that diseases could be transmitted by graywater contact, graywater should be used carefully. (440) Graywater can be used safely to water fruit and other trees, or in landscaping. It can also be used for vegetables if it is applied sub-surface with a soaker hose or by some other sub-surface system. Sub-surface application is the most preferred way to use graywater because direct exposure to graywater is eliminated and soil organisms kill pathogens. (441) Soaker hoses can also be used with relative safety on the surface in gardens since water applied by them does not splash onto the edible parts of plants. Although the uptake of pathogens by root crops does not take place, root crops watered with graywater should be carefully washed and/or well cooked before they are consumed. To maximize safety, graywater can be disinfected before it is applied. Historically, water has been disinfected by adding chlorine. Chlorine does disinfect but its use can also result in the creation of compounds like chloramine. Chloramine, which is toxic to soil and aquatic organisms, results when chlorine reacts with the carbon in water borne organic materials. If the level of organic materials is low, the amount of chloramine created is small. But if the organic load is high, the amount of chloramine produced becomes a problem. Chlorine is also toxic to soil and aquatic organisms but it dissipates faster than chloramine. If water is disinfected with ozone, this problem is avoided. Ozone, a form of oxygen that links three atoms of oxygen together, is even more effective at killing pathogens than chlorine and does not cause harmful side affects. It can also break down many organic pollutants and can be used to remove heavy metals through a process of precipitation. (442) Though the adoption of ozone water treatment systems in the U.S. has been slow, ozonization has replaced chlorine in 99% of the swimming pools in Western Europe. (443) Soaps containing phosphates can also be used without negative consequences in most graywater recycling situations. Phosphate is a much maligned nutrient because it stimulates aquatic plant growth in lakes and waterways. These plant "blooms" can cause fish to die from suffocation. At night aquatic plants need oxygen which they extract from the water. If the number of aquatic plants in a volume of water is excessive, oxygen levels can drop below levels that can support fish. (444) Excessive plant growth also threatens fish with suffocation when plants die in the autumn. With large quantities of dead plant material available, decay bacteria multiply rapidly. These bacteria require oxygen and can quickly reduce the oxygen content in a body of water to levels below which fish can survive. (445) In soil, however, phosphate is a nutrient readily useable by plants and need only be avoided if there is a possibility that the phosphate will enter a waterway instead of becoming part of a terrestrial plant. Though they are usually thought of as waste elimination processes, septic tank leach field systems can be excellent water and nutrient recyclers. A leach field is made up of lines of perforated pipe buried 4 to 5 feet deep on level contours so that the wastewater is evenly distributed throughout the whole leach field. Additionally, leach pipes are surrounded by coarse sand and an 18" layer of one inch rocks to keep the perforated pipes from getting clogged by soil or plant roots. When wastewater leaves a house it passes through a septic tank where some of the solids are biologically broken down. From the tank the partially processed wastewater flows into the leach field where it seeps through the perforations in the pipe into the surrounding rock and then into the soil. Once in the earth, soil organisms complete the process of killing pathogens and converting the wastewater borne nutrients into inorganic compounds which plants can use. The water that carries these waste materials provides irrigation. The recycling process is completed when plants watered and fertilized in this way lose their leaves, or die and decay to become part of the surface soil. These plant materials can also be recycled by collecting and composting them so the nutrients they extracted from the leach field can be used as fertilizer in other locations. Since leach fields pipes are typically laid at a depth of five feet it is essential that the plants grown in conjunction with them have roots that go deep enough (6 feet or deeper) to take advantage of the water and nutrients available. If leach field pipes are installed closer to the surface, plants with shallower root systems can also be used. On whatever level it occurs, it is important to keep toxic and caustic materials, like some drain openers, out of recycling systems. These materials can damage or kill the various organisms that help in the recycling process. With the exception of lead from pipe solder or silver, which is a waste from photo processing, heavy metals and other industrial toxins are not usually found in graywater. But where industry is hooked into municipal treatment systems such materials are often present. Heavy metals and other toxins can concentrate in the food chain when water or composted sludge contaminated with them is used to irrigate and fertilize plants. (446) |
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In dense urban areas, where many residences do not have yards, community sized wastewater recycling systems are a more practical choice for recycling wastewater. As with individual residence systems it is important to keep toxic and caustic materials out of all wastewater collection and recycling processes. If this is done there are a number of processes that can be used to clean up wastewater so it can be used for irrigation. In general such recycling systems use both biological and mechanical methods to clean wastewater. Biological systems can be used exclusively where land availability is not an issue. In Arcata California a marsh system is used to treat the community's sewage. As the sewage flows through the marsh, aquatic organisms consume and convert the waste into nutrients that marsh plants then convert into plant growth. While the water in this system is not reclaimed for irrigation it does enhance the marsh's aquatic environment. (447) Where land area is limited or expensive, the land area required for biological treatment can be reduced by additional human manipulation. The new Alchemist Institute under the direction of John Todd has developed a treatment process which uses greenhouses and translucent tanks to maximize decomposition and photosynthesis. As the wastewater flows through a series of semi-transparent tanks a complex community of aquatic plants and animals purify the water by consuming and converting the organic waste into animals and plants (biomass). At the end of the process, the clean water can be used for irrigation or it can be safely discharged into streams. In addition to water, the process also produces a crop of fish and other aquatic organisms and aquatic plants that can be composted and used as a soil amendment. (448) A third approach has been developed in Tijuana, Mexico. The treatment plant in Tijuana is called Eco-Parque. The Mexican system combines biological and mechanical methods to process wastewater to minimize the amount of land needed for treatment. The treatment process involves mechanical screens, biological filters, clarification (slowing the flow of water so solids can settle out) and disinfection. The goal of this project is to recycle all the water and nutrients that pass through it. The recycled water is being used for irrigation and the nutrient rich solids are composted and used as soil amendments. (449) |
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As in other areas, water use for landscaping and gardening can be significantly reduced. In low rainfall areas, the amount of water used for residential landscape irrigation can average 50 or more gallons per day per capita. (450) The use of water efficient irrigation equipment and selecting landscaping schemes and plants that are suitable for the climate where they are located can greatly reduce this requirement. Efficient water use in landscaping does not mean that landscaping themes have to be sparse. Even in arid areas there are numerous beautiful plants from which to select. (451) Nor does such a strategy preclude having a vegetable garden, fruit trees, or grass. Reducing water use in other parts of a landscape frees up water for these purposes. If climate appropriate landscaping is combined with water efficient irrigation equipment, even more water can be saved. Water efficient irrigation equipment ranges from various drip irrigation systems and low flow drip emitters and sprinklers to sophisticated irrigation control tools called tensiometers. Tensiometers are electronic devices that are installed in the soil where they measure soil moisture content. They can be read and water applied accordingly or they can be used to activate automated irrigation systems when water is needed. On the plant side, there are literally hundreds of attractive drought tolerant trees, shrubs, vines, and ground covers that can be included as part of a low water use landscape palette. (452) Additionally, there are numerous drought tolerant plants that produce food and other useful materials. These plants include the California Black Walnut tree, the fig family, the Oriental Persimmon, the Quince tree, members of the grape family, the Guava family, loquat trees, Aloe, Bamboo, and many more. (453) Even modest efforts toward coupling water efficient irrigation systems with climate appropriate plants in landscaping could cut irrigation requirements in low rainfall areas in half. (454) If climate appropriate plants are used exclusively, irrigation requirements can be reduced to zero after plants become established. If graywater recycling systems are incorporated, even relatively water intensive landscapes can be successful without using potable water for irrigation. |
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Just as in the residential sector, commercial and industrial users can cut water consumption through water recycling and use of water efficient fixtures and appliances. Changes in operational strategies and manufacturing processes can increase efficient water use even more. In 1978, U.S. manufacturing industries used each unit of water 3.4 times before it was discharged. By the year 2,000, experts predict that the water reuse rate for industry will have increased to over 17 times before discharge. (455) Some innovative firms have already achieved or exceeded this level of efficiency. "Armco steel mill in Kansas City, Missouri, which manufactures steel bars from recycled ferrous scrap, (scrap iron and steel) draws into the mill only 9 cubic meters of water per ton of steel produced, compared with as much as 100-200 cubic meters per ton in many other steel mills -- the Armco plant uses each liter of water 16 times before releasing it after final treatment, to the river." (456) "One paper mill in Hadera, Israel, requires only 12 cubic meters of water per ton of paper (produced), whereas many of the world's paper mills use 7-10 times this amount." (457) Pioneer Metal Finishing, a plating firm in New Jersey, has developed a water recycling process that totally eliminates sewer discharge. In the Pioneer process, all water is recycled and most of the chemicals and metals extracted from it are reused. Pioneer is now looking for a use for the small quantity of dry residue left over from their recycling operation. (458) Water use in industry can also be cut by using non-chemical water treatment processes to prevent biological fouling and water scale buildup in boilers, water lines, and cooling systems. Non-chemical water treatment consists of exposing water to magnetic and electrostatic fields to prevent mineral scale from attaching itself to pipes and other metal surfaces and to remove such deposits where they already exist. Non-chemical treatment also creates an environment hostile to the growth of water borne bacteria, fungus, and algae. The buildup of scale and bacterial slime reduces the efficiency of heating and cooling systems by restricting water flow rates and by insulating heat exchange elements. A 1/16 inch scale buildup requires 15% more fuel to achieve the same heating results. A 1/4 inch buildup increases fuel consumption by 39%. (459) In the U.S., chemicals have been the predominant method used for treating such problems. But chemical treatments are relatively labor and material intensive because they need regular chemical mixture adjustments. Maintenance is also high because chemical treatments reduce the rate of scale build up but do not prevent it. This means that heating and cooling systems have to be drained and manually cleaned on a regular basis. Additionally, all the water in chemically treated systems must be periodically purged because evaporation losses increase the concentrations of chemicals and minerals beyond acceptable levels. This purging wastes water and releases treatment chemicals like algaecides, fungicides, bactericides, and phosphates into the environment. (460) Non-chemical treatment minimizes or avoids most of these problems. Although they have been slow to catch on in the U.S., non-chemical treatment systems have been the preferred treatment choice in Europe and in the Russian Commonwealth for decades. But this is changing as is evidenced by the numerous high profile firms like Kodak, IBM, Hewlett Packard, Ford Motors, Holiday Inn, Pepsi Cola, Coca Cola, Marriott, and Bantam Books that have already switched to non-chemical treatment processes. (461) |
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In addition to saving water, using water more efficiently has other benefits. Efficient irrigation practices and growing water efficient crops help to avoid the build up of salt and other minerals in soils. As rainwater runoff travels over and through the ground, salt and other minerals are dissolved into it. When this mineral laden water is used for irrigation the salts and minerals it contains are left in the soil when the water evaporates or is transpired by plants. If irrigation water is used efficiently there is less water to evaporate and thus less of a salt and mineral build up. A smaller mineral buildup makes it easier for rainfall or intentional periodic flooding to leach the accumulated minerals and salts out of the soil. Rainwater runoff from efficiently irrigated agricultural soils is also less salty than it would be with less efficient irrigation practices and is thus more useable for other purposes. Efficient water use saves energy and minimizes energy related pollution by reducing the amount of energy required to pump water out of the ground and to deliver it from distant sources. It also means that fewer rivers will be dammed or otherwise modified, and that smaller less costly conveyance systems can be used to deliver water when local supplies are inadequate. More efficient water use also means that stored water will last longer during periods of drought. Though the relationship is less direct, efficient water use also minimizes the environmental impact of building wastewater treatment facilities to treat urban sewage. With smaller quantities of water to treat, less energy, concrete, and other resources are needed to build and operate treatment centers. Reducing the amount of energy and materials needed to build and operate treatment systems also reduces the amount of watershed damage related to the procurement of such resources. By reducing pollution it also reduces the amount of pollution entering waterways and groundwater deposits. |
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Another aspect of creating a more water secure future is the vital need to protect watersheds and the waterways and groundwater storage areas which they supply. A watershed is a drainage basin composed of a valley and the surrounding slopes which collect and direct the flow of rainfall and snow melt runoff. Watersheds are also the home of complex interdependent plant and animal communities which are vital to watershed function and its health. Many watersheds are small. Usually smaller watersheds empty into larger ones. The great rivers of the world are all supplied by runoff from numerous smaller watersheds that result in one large watershed or drainage basin for each river. Actually all land areas above sea level are part of one watershed or another. In a healthy watershed, rainwater runoff carries very little sediment and nutrients. Even when rainfall is heavy, streams and rivers run clean. This is because plant leaves and the ground carpet they form when they fall protect the soil from pounding rain. (462) Plant root systems, along with tunneling soil organisms, also help store water by making it easier for water to be absorbed into the soil. Rainwater and snow melt runoff are also slowed by this process. By slowing runoff and storing water, watershed communities perform three important functions. First is the function of self preservation. By storing water and slowing runoff the watershed's plant and animal community perpetuates itself by insuring that it has an adequate water supply during dry periods. Second, the slow release of watershed stored water through springs evens out the flow of rivers and streams so they continue to flow long after the wet season has past. (463) Finally, this slowing and storage process helps to increase groundwater supplies by allowing more time for water to percolate down into groundwater aquifers for storage. In addition to providing the services just discussed, all the organic material in our planet's soils have been produced by the plant and animal communities that inhabit the world's watersheds. In a healthy watershed, the processes described above happen naturally. But if we use watersheds inappropriately and extract resources from them incorrectly, the watershed community and the functions it performs will be crippled and can even collapse. Watershed communities worldwide are under attack. If present practices persist, human activities will be driving "100 species (of plants and animals) to extinction every day," over the next three decades. (464) This "is at least 1,000 times the pace that has prevailed since prehistory." (465) At this rate, not only are we losing species, but whole ecosystems, the "nurseries of new life forms." (466) Harvard biologist E.O. Wilson describes this phenomenon as the "'death of birth.'" (467) "Wilson estimates that people have recently begun to extinguish lesser creatures at a pace 10,000 times the typical natural rate." (468) "British ecologist Norman Myers has called it the 'greatest single setback to life's abundance and diversity since the first flickerings of life almost 4 billion years ago.'" (469) One might argue that the extinction of one or even thousands of species of life, in a world that is home to millions of species, is of little consequence. But the long-term effect of the loss of even a single species is not easily known. (470) History has shown that eliminating certain organisms from an ecosystem can have unanticipated effects. Early in the 20th Century people in Kern County California waged a 20 year battle "against annoying predators: skunks, foxes, badgers, weasels, snakes, hawks, owls." (471) In 1924 the war against predators was escalated when Kern County sheep herders "hired a U.S. Biological Survey team to wipe out the coyotes." (472) By 1926 crop yields were the best ever, but by the following Spring the lack of predators resulted in Kern County being inundated by 100 million starving field mice which even killed and ate sheep in their hunger. (473) Even when the target of animal control measures is the prey rather than the predator, problems can emerge. This was borne out in an experiment where rodents and rabbits were intensively poisoned and trapped in one area and then had their population levels compared with those of another area where such measures were not applied. The study found that the population levels of rabbits and rodents in the area where poisons and traps were used was soon larger than the comparison area where nature was not interfered with. The reason given for this phenomenon was that as poisoned animals died they were eaten by predators which died as well. With fewer predators available to eat them, the rodent/rabbit population quickly grew beyond previous natural levels. (474) Even if poison is not used to kill prey animals, a substantial reduction in the prey animal population could cause a similar imbalance. If the population of prey animals is greatly reduced by any means, predator populations will fall as well as the result of starvation or through migration to where food is more plentiful. In the absence of predators, prey population will quickly grow beyond normal levels until the slower reproducing predator population can rebound. |
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We are still quite a ways from fully understanding all the intricacies of watershed mechanics. But in a general sense we know how present practices harm them and how watershed resources can be used in ways that minimize negative ecological impacts. |
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Agriculture, as it is commonly practiced, is not as effective at slowing runoff and storing water as the plant and animal communities it replaces. With conventional agriculture land is frequently unprotected by vegetation. Even when crops are grown the soil is often only partially protected compared with natural vegetation. When land previously farmed is converted to grassland or woodland "it will store roughly 16 more tons of carbon (embodied in plant material) than when it was cultivated." (475) Without protection, topsoil is easily eroded by pounding rain. Hard rainfall on bare soil often has the effect of sealing the soil surface so as to block water absorption. This speeds runoff and increases erosion down stream. The use of chemical fertilizers in lieu of organic fertilizers can also increase soil erosion. Conventional agriculture often relies on chemical fertilizers to supply plant nutrients instead of using organic materials like manure and plant residues. A reduction in the amount of organic material in soils translates into less food for soil organisms. Fewer soil organisms means that there are fewer passageways in the soil through which water can be absorbed. Less absorption translates into more runoff which increases soil erosion. It also reduces the amount of water stored in the soil and as groundwater. Once set in motion, the loss of fertile topsoil tends to perpetuate itself, making it harder for watershed communities to recover after they have been damaged. A weakened watershed function results in more erosion which further weakens the watershed community which causes more erosion and so forth. This is true whether agriculture is continued or if a natural watershed community tries to re-establish itself after agriculture has been discontinued. |
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Even though many of today's agricultural practices are watershed damaging there are a wide variety of techniques that can be adopted to maximize the watershed function of agricultural systems. One way to blunt the effects of pounding rain and runoff from rainfall and snow melt is to leave crop residues in the field. Plant residues can either be left standing or used on the soil surface as a mulch or in combination with mulch. Because its root systems are intact, standing vegetation can offer additional protection from water and wind erosion. Leaving plant residues in the field also helps watershed function by providing food for soil organisms. The tunnels they create in the pursuit of food make it easier for water to be absorbed by the soil. There are a variety of tillage methods that can be used to prepare soils for planting that minimize the impact of agriculture on the watershed fabric. These include chisel plowing, strip tillage, ridge tillage, and no-tillage methods. Chisel plowing, a method of plowing that only opens a narrow furrow of soil, can reduce erosion losses by up to 50% over more commonly used cultivation practices. (476) "The use of no tillage, strip tillage, and ridge tillage ... can decrease erosion by 75% or more." (477) Growing nitrogen fixing legumes along with crops and as rotation crops can also improve the watershed function of agricultural systems. These crops protect the soil from wind and water erosion and provide food for soil organisms which, in turn, make the soil more permeable by their tunneling activities. Adding organic materials to the soil, like manure, also improves watershed function. Manure-like materials absorb water like a sponge and provide food for tunneling soil organisms. "Increasing soil organic matter by applying livestock manure increased the water infiltration rate by more than 90% (Meek and Donovan, 1982; Sweeten and Mathers, 1985) mainly by decreasing the rate of water runoff (Mueller et al., 1984)." (478) Planting trees and shrubs to form windbreaks is a good way to protect soils from the erosive effects of the wind. "Soil particles do not ordinarily blow away until wind velocity is about 13 miles per hour 1 foot above the ground." (479) A well established windbreak can provide full protection against wind blown soil losses "10 times the height of the trees measured in the direction the wind is blowing. And they give some protection as far out as 20 times the height of the trees." (480) Windbreaks also "make sprinkler irrigation more effective" by protecting "the spray against shifting winds." (481) The use of windbreaks can also increase crop yields. "In a project aided by CARE in the Majjia Valley of Niger, for instance, trees planted to form windbreaks around cropland boosted grain yields more than 20 percent and also produced wood needed for fuel and timber." (482) Windbreaks also "increase both dew fall and the number of birds and small animals by providing cover, food, nesting sites, and storm protection. In summer, farmstead windbreaks raise humidity and produce an air conditioning effect. In winter, they decrease livestock deaths, heat, and feed needs." (483) Though it is just one aspect of food production, the grazing of livestock on rangeland has a particularly negative effect on watershed function. Livestock grazing on range and forest lands decreases the water holding capacity of watersheds by removing soil protecting vegetation. (484) This translates into soil erosion which, in turn, results in less and weaker vegetation leading to further soil loss and eventually the formation of gullies. Topsoil loss in the U.S. is around 3.1 billion tons per year. (485) Around 85 percent of this loss can be attributed "to the feet of grazing livestock or to the production of livestock feed." (486) As early as 1974 the Bureau of Land Reclamation reported "that less than one-fifth of the grazing lands in the United States were in "'good to excellent'" condition. (487) Even in forestlands, where one would expect that tree canopies would protect against erosion, livestock grazing has a negative impact. Soil erosion on grazed forestlands is "six times the rate experienced on non-grazed forestlands." (488) Grazing, especially grazing cattle, is particularly damaging to streams and stream related vegetation. Cattle cause damage because they break down stream banks and trample stream vegetation. "A 1990 EPA report stated that "'riparian areas through much of the West (in the late 1980s) were in the worst condition in history.'" (489) Livestock grazing has a similar effect on the rest of the planet. "Livestock grazing and livestock crop production cause accelerated soil loss over more of the globe than any other land use." Even if we do not count the land used to grow grain and other supplemental food for livestock, overgrazing livestock alone is the largest cause of soil degradation on our planet. (490) If it is done carefully, domestic animals can be grazed on some range land areas without seriously compromising their watershed function. But to avoid serious damage, grazing and its timing need to be carefully regulated. Considering the damage that they cause to watersheds in general and to streams and ponds in particular, it may be advisable to prohibit livestock grazing, particularly cattle, which cause the most damage, in most range and forest land areas. The overall economic impact of such a policy in the U.S. would be relatively minor since only three percent of the beef grown nationally is rangeland fed. (491) It would be important however, to work with ranchers who earn their livings raising range fed cattle to mitigate any negative economic impacts that such a policy would create for them. |
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Timber harvesting is another way that human activity impacts watershed function. Clear cutting, the most prevalent method of timber harvesting, completely eliminates large stands of vegetation during the process of harvesting trees. This results in the almost total disruption of the plant and animal communities that are essential to the retention of forest soils, the water they store, and the water that percolates through them into groundwater storage basins. Though professional foresters do not agree completely as to the best strategy or strategies for both harvesting timber and protecting watershed communities, some general strategies are emerging. If more than a few trees are harvested in one area they should be harvested in narrow bands along contours to minimize the problem of erosion. Harvesting vegetation counter to contours opens the soil up to the formation of erosion gullies. Trees close to waterways should only be harvested individually and if they can be harvested in a way that avoids waterway siltation. Stream siltation has been identified as a factor in the decline of salmon, and cut-throat-trout in the Pacific Northwest. (492)Forest floor debris or duff should be spread on soil areas disturbed by felling or from dragging trees or by logging equipment. This practice minimizes the effects of erosive rainfall. Road building in forested areas should be limited. Often the grading of access roads can be just as destructive to watersheds as the harvesting itself. (493) In one study, a single road slide (caused by erosion) contributed to 40% of the sediment lost from the watershed area being examined during the study year. (494) To avoid the need for roads, timber harvested in remote areas should be moved to transport centers by helicopters, horses, or balloons. Currently, around 8 percent of the logs harvested in the Pacific Northwest are moved to loading areas by one of these methods. (495) Only the tree boles, the main wood portion of a tree, should be removed | |
