ARTICLE INDEX
Volume 3, Number 1
February 1993

WATER -- THE ESSENTIAL NUTRIENT
Water is the most important element in life. Some organisms can live without air, but no form of life has ever been found that can survive without water. From the world's earliest known history, people have always lived near rivers and lakes, where they had access to fresh water.

Nearly 60 percent of our body weight consists of water. Considering that adult bodies are nearly two-thirds water, this means that for a 150-pound person, 90 pounds, or 45 quarts, is water. We need to replace about 3 or 4 percent of our system's water each day. A loss of 1 percent of our necessary water level results in thirst, and possible pain. A loss of 5 percent can lead to hallucination, while a 10 percent loss in children -- 15 percent in adults -- will lead to death.

Water helps our bodies in the following ways:

• It carries nutrients and oxygen to all parts of the body through blood and lymph.
• It helps regulate body temperature by allowing heat to escape through perspiration.
• It acts as a lubricant around joints and as a shock absorber inside the eyes and in the spinal cord.
• It maintains physical work performance. Just a 4 or 5 percent decrease in body water will result in a 20 to 30 percent decline in efficiency.
• It helps food to be digested and converted to energy.

Besides water from the tap, all the beverages we drink contain water: coffee, tea, milk, soft drinks, and juices. Other water sources include soups and gelatins. Solid foods contain various amounts of water. Tomatoes are 95 percent water, and potatoes are 80 percent water. Meats are between 50 and 70 percent water, while bread is approximately 35 percent water.

The quality and quantity of this essential nutrient can affect our lives many times every day. From our morning cup of coffee to washing our hands; from making soup for lunch to doing the laundry, we depend on water. Most of us take our water for granted, but we shouldn't -- water is too important to our existence to not be protected.
(Source USDA-ES)

SELECTING A HOME WATER TREATMENT SYSTEM
If your water smells bad or tastes bad, or makes food and drink taste bad, or if your water contains excessive gas bubbles, or is cloudy or colored, or if it stains clothes or fixtures, or leaves a scum when mixed with soap, or if piping and fixtures corrode rapidly, it probably needs one or more treatment devices. On the other hand, many contaminants, both biological and chemical, show no obvious symptoms in the water. They can be identified only by having specific water samples tested by a qualified laboratory.

Treatment equipment for home systems should be selected to correct or prevent specific water quality problems. There are several major concerns:

1. Match the treatment facility to the contaminants. All treatment facilities have their limitations. A single unit cannot correct all water quality problems.
2. Match the treatment facility to the household. The capacity of any corrective unit should be sized to meet the maximum anticipated needs and wants of the persons in the household.
3. A treatment facility will require maintenance. There is no such thing as an "install it and forget about it" water treatment facility. Units will remain effective only if they receive proper maintenance.
Some common types of water treatment units and their characteristics:
• Physical filters
• Can be made from sand, fabric, fiber, ceramic, or other screening material.
• Remove particulates such as grit, sediment, dirt, or rust.
• Some can remove small organisms like cysts and small particles like asbestos fibers.
• They do not correct biologically unsafe water.
• Biological filters
• Use a developed layer of nonharmful microorganisms to trap and destroy certain harmful organisms like Giardia cysts.
• They do not remove or destroy all harmful organisms.
• Activated carbon filters
• Improve the taste, smell, and appearance of water (except for rotten egg smell).
• Remove volatile organic chemicals, trihalomethanes, and certain pesticides.
• Are effective in reducing chlorine content.
• Granular activated carbon (GAC) adsorption is effective for radon removal.
• Activated carbon filters are not effective in removing most inorganic chemicals such as salts or metals.
• They can harbor and propagate bacteria.
• "Specialty" activated carbon filters are effective in removing lead.
• They are not disinfectants. Even if registered as bacteriostatic, they are inadequate to treat microbiologically unsafe water.
• Distillation units
• Vaporize the water, then condense it, leaving many impurities behind.
• Remove most dissolved solids: salts, metals, minerals, asbestos fibers, particles, and some organic chemicals.
• Do not remove all chemicals.
• May allow some bacteria to pass through.
• Must be cleaned regularly to remove mineral buildup on interior surfaces.
• Rate of output is very limited.
• Ultraviolet (UV) disinfection units
• Ultraviolet radiation kills bacteria and inactivates viruses.
• They destroy tastes and odors.
• They do not remove most chemical pollutants.
• They have questionable effectiveness against spores and cysts.
• Require regular cleaning to prevent blockage of UV light.
• Chlorinators
• Motor driven pump injects chlorine (usually pellets) into water source at a preset rate consistent with water flow.
• Remove iron bacteria, disease-causing bacteria and algae.
• May combine with inorganics in water to form dangerous trihalomethanes.
• Require regular monitoring to assure proper chlorine level.
• Reverse osmosis (RO) units
• Work by forcing water under pressure to pass through a membrane, extracting impurities.
• Remove substantial amounts of most inorganic chemicals, such as salts, metals (including lead), asbestos, minerals (including sodium), nitrates, and some organic chemicals.
• They do not correct microbiologically unsafe water.
• They may waste up to 4 gallons of water for each gallon of treated water produced.
• Membranes must be replaced regularly.
• Rate of output is very limited.
• Water softeners
• Remove mineral ions that cause hardness (calcium and magnesium) and replace them with sodium ions. (See last item below.)
• Reduce the buildup of hard water deposits in pipes and on fixtures.
• Improve the economics and the efficiency of washing/cleaning operations by allowing the use of less soap and less hot water.
• Water softeners are being marketed that use potassium instead of sodium in the ion exchange process.
• Increased sodium content of softened water is not desirable for people on salt free or low-salt diets.


TIMBER HARVESTING AND WATER QUALITY
Forests are very important to Idaho's water quality. Forests cover over 41 percent of Idaho's total land area and receive more rainfall than nonforested areas. Twelve percent of Idaho forests are owned by over 37,000 farmers, retirees, and other nonindustrial private owners.

Prevention is the Cure
Under natural conditions water quality from forests is relatively high. When timber is harvested, sediment from soil disturbed by roads and skid trails may degrade forest water quality, especially during the first few years after harvest. The best way to maintain forest water quality at harvest is through well-planned and executed logging and road building.

Here are a few points for "water quality-friendly" timber harvesting:


• Get to know your property. Locate landslides, old slumps, and other areas vulnerable to erosion, and use extra precautions when road building and harvesting.
• Assemble a forest management plan. A written forest management plan helps frame decisions affecting water quality and other forest values. It also helps communicate your wishes to loggers and others working on the property.
• Build roads in secure places. Build roads along contours, on ridges rather than drainages, and away from highly erodible sites.
• Keep as little area in roads and skid trails as possible. Roads and skid trails are compacted and more prone to erosion. They also take valuable tree growing ground out of production. The less mileage and width in roads and skid trails, the better.
• Plan roads and skid trails for future harvests. Well planned roads and "designated" skid trails can be used for future harvests as well, to avoid new erosion.
• Build adequate drainage into roads; drain-age structures (water bars, culverts, etc.) divert water from the road quickly, to prevent erosion and saturation, which may lead to road failure.
• Use the least disturbing logging methods and timing. Logging disturbs and compacts soil, which can make it more vulnerable to erosion. Choose the least disturbing skidding method (cable, tractor, etc.) practical for the harvest. Also, wet soils are much more vulnerable to compaction and disturbance than dry or frozen soils.
• Get a written contract for timber sales. The Idaho Forest Practices Act (FPA) sets minimum standards for timber harvest practices. A written timber sale contract can be used to build further incentives to maintain water quality.
The Idaho Forest Practices Act
The Idaho Forest Practices Act specifies minimum best management practices to ensure woodland water quality and other forest values. Idaho Department of Lands has professional foresters ("Forest Practice Advisers") who inspect harvest operations for FPA compliance, and provide on-the-ground technical assistance to help you maintain forest water quality.

For more detailed information on improving forest water quality, stop by your local extension office and ask for PNW 915, Impacts of Forest Practices on Surface Erosion, or other extension publications on water quality or forestry.
(Chris Schnepf, Area Extension Forestry Agent)



CAN YOU PASS THIS WATER QUIZ?
Here are 20 quick questions to find out how much you know about drinking water. Mark the following true or false. Answers are found on page 8 of this newsletter.

1. Installing a low-flow toilet can save a family of four more than 45 gallons of water a day.
2. More than 75 percent of the water in the United States is located underground.
3. Reading the labels on common household products won't tell you what products are harmful to water.
4. Americans improperly dispose of more oil in a year than the Exxon Valdez spilled.
5. Even when a recipe calls for using warm or hot water, you should draw cold water from the tap and heat it on the stove or in the microwave.
6. It's safe to drink water directly from remote streams.
7. If you have your own well, you can be sure your water is safe.
8. There are ways to landscape that use between 30 and 80 percent less water than traditional landscaping.
9. You can drink more than 4,000 eight-ounce glasses of tap water for the same cost as a six-pack of soda pop.
10. Common outdoor bug and weed killers can contaminate underground water or end up in your local river or lake.
11. The quality of U.S. drinking water is not regulated by the federal government for safety.
12. Two-thirds of the water you use at home you use in the bathroom.
13. Trash and debris around a lake won't affect water quality.
14. It's better for water if you dry out leftover household products such as furniture polish, car wax, or latex paint, before disposing of them.
15. More than 800,000 new water wells are drilled each year for domestic, commercial, and industrial use.
16. Letting the water run while you brush your teeth or shave is water wise.
17. New water sources are being discovered every day.
18. An abandoned well can be left unsealed without jeopardizing the groundwater source.
19. You can ignore a leaky faucet at work or at school . . . it's only worth saving water at home.
20. You can influence decisions your community makes on drinking water.


HOW EFFECTIVE ARE AGRICULTURAL BMPs?
(This is the second in a series of four articles on agricultural BMPs)
The effectiveness of BMPs can be rated in terms of their impact on pollutant loads, acceptability by farmers, cost-effectiveness, and ease of implementation and maintenance. An effective BMP also has minimum negative impact or tradeoffs. Clearly, source controls for the most part meet all of these criteria, and, for intractable pollutants, total ban is the only solution. But this approach can be applied only when there are such suitable alternatives as substitute compounds.

Source reductions also are effective if the degree of reduction is large enough to have an impact on pollutant loadings. For example, reducing land application of manure from 20 to 30 tons per acre per year down to 5 to 10 tons per acre per year will have a significant impact on nitrate leaching. Reducing nitrogen fertilizer use by 10 percent will have much less effect. Source control is also most effective when the potential for transport to surface water or groundwater is high. Back-siphoning in chemigation systems, discharge of pesticide rinsewater directly to streams or in the vicinity of wells, and direct runoff of manure all produce very high local concentrations of pollutants that require source control for optimum management.

BMPs that reduce transport of pollutants to surface water or groundwater are less effective than source controls. The impact of BMPs is dictated by variability in local climatic and hydrologic conditions. Because these impacts are not easy to account for, it is difficult to reduce leaching of groundwater contaminants.

1. Protection from Nitrate
The degree of implementation of a particular practice will determine its overall effectiveness. For nitrate, the most effective approach is restricting application rate to coincide with crop requirements. This is particularly true for crops with high nitrogen fertilizer requirements, for land application of livestock wastes, and for irrigation water management. The difficulty is in establishing nitrate rate limits that protect the farmer against both seasonal variations in a crop's nitrogen use efficiency and such nonleaching losses as denitrification. More efficient nitrogen-use practices, such as split applications, have not been accepted widely by farmers because of both greater time and management required as well as risk of crop yield reductions with these practices.

In areas where concentrated livestock operations result in excessive manure applications, applying a strict nitrogen application rate limit to lands receiving livestock waste would have a significant impact on nitrate levels in local groundwater. Monitoring of day-to-day manure application is not feasible, but requiring manure management plans for an entire livestock operation is reasonable if the land base is adequate for application at nitrogen crop utilization rates.

2. Protection from Pesticides
Pesticide contamination of groundwater is both compound specific and site specific, suggesting that the problem is not so widespread as that of nitrate contamination. It also offers insights for its control. FIFRA provisions, which currently include leachability of the compound, could be expanded to include label restrictions based on site- or region-specific soil, bedrock, and climatic conditions favoring pesticide movement to groundwater. This is essentially the approach employed by California.

The U.S. Environmental Protection Agency's (EPA) Wellhead Protection Program, which establishes statutory requirements for state wellhead protection programs, is an effective approach to protecting public water supply wells and could be expanded over time to include private wells. Implementing wellhead protection measures will require applicator training under FIFRA and Extension education programs, but these are measures that farmers likely will accept. Such measures as sprayer calibration and better rinsing and disposal of pesticide containers can be effective in protecting individual wells.

There is significant potential for integrate pest management (IPM) to decrease pesticide use and, therefore, the risk of groundwater contamination. Because IPM comprises a broad set of practices, quantifying its adoption can be difficult. It appears, however, that the full range of IPM practices has had only limited farmer acceptance. IPM requires considerable time and greater management skills, and it may be perceived as riskier than prophylactic or calendar scheduled pesticide use. Unless mandated by law, or unless Extension and research priorities shift more dramatically in favor of IPM, it is unlikely to have much impact on future pesticide use.
(Adapted from Groundwater and Public Policy, Series No. 5 by T. J. Logan)



RESEARCH UPDATE: FIELD INVESTIGATION OF LANDFILL DISPOSAL OF CULL ONIONS
Recent surveys in Idaho show that nitrates are being found in some major aquifers across the state which the Idaho Division of Environmental Quality has identified as vulnerable resources. Some of man-induced groundwater contamination results from agrichemical use, such as nitrogen fertilization, but nitrates may enter groundwater in other ways. One suspected source of groundwater nitrate contamination is from the landfill disposal of cull onions in the Treasure Valley region.

The Treasure Valley region of southwestern Idaho and eastern Oregon supports a large onion industry. Onion packing operations generate large quantities of cull onions. Cull onions result from mechanical damage during harvest and handling before storage, spoilage, or poor quality related to size and shape. Cull onions account for approximately 21 percent of the harvested onion crop each year resulting in about 100,000 tons of onion by-products per year. Both Idaho and Oregon have specific regulations regarding acceptable practices of cull onion disposal. Current acceptable methods include burial pit disposal, surface application, and incorporation into field soils.

Current disposal methods are aimed at minimizing insect and disease problems. The disposal of cull onions using landfill techniques is necessary for the control of onion maggots and odors. Cull onions, if exposed, can provide overwintering and breeding sites and result in onion maggot infestations. It is not known if present practices of cull onion disposal in deep trenches represent a potential contamination hazard to groundwater in this region. Leachate that contains relatively high concentrations of nitrates and other compounds may form as the cull onions decompose and compress. The possibility that this disposal method is a potential contamination hazard to the region's groundwater is sufficient cause for both Idaho and Oregon to question the use of such practices.

There is no current information available regarding cull onion pit disposal as a source of groundwater nitrate contamination under the climatic and soil conditions of the Treasure Valley. Therefore, an applied research project under the direction of John Hammel, a soil physicist at the University of Idaho, and James Osiensky, a hydrogeologist employed by the University of Idaho stationed at Boise State University, was developed. This field investigation of landfill disposal of cull onions seeks to (1) allow an informed decision for the future use of burial pit disposal of cull onions, and (2) provide the onion industry with information to make viable economic decisions pertaining to the proper disposal of cullage. This project is being supported with funds from the Idaho-Eastern Oregon Onion Growers, Idaho Division of Environmental Quality, and the Idaho Agricultural Experiment Station.

The proposed research project is currently being conducted at a landfill site in Payette County, Idaho, approximately 3 miles east of Nyssa, Oregon. The objective of the proposed research is to study the creation and movement of nitrate leachate from the decomposing onions in a typical disposal pit configuration. An initial disposal pit was dug in the summer of 1991 and cull onion disposal was started in October. The pit was the same size as other pits used in the Treasure Valley area. Dimensions of the pit in feet were approximately 246 in length, 16 deep, 13 wide at the base, and 40 wide at the top. The pit was divided into three 82-foot sections. Three sets of soil-water samplers (suction lysimeters) at three depths (1.5, 3.25, and 6.5 feet) were placed in each section. Soil-water sampler access tubes were mounted in the facility for monthly soil-water sample collection. In addition, two piezometers were positioned within the center pit section to obtain samples of leachate before movement into the pit base. A tracer of potassium bromide was placed in a narrow trench over the center set of soil-water samplers in each section. The movement of the tracer through the soil will enable monitoring of vertical movement and subsurface lateral movement of the leachate.

Soil samples were collected every foot to the 6.5 foot depth of the pit during the equipment installation. These samples were analyzed for nitrate and bromide to provide background levels before cull onion disposal at the site. The disposal pit was completely filled by January 1992 and covered with a soil cap at that time. Soil-water samples were collected at monthly intervals beginning in March 1992. Samples obtained were analyzed for both nitrate and bromide. At this time, onion breakdown products have moved to all depths of the pit. No nitrates have been found in any of the samples analyzed.

Anaerobic (without oxygen) decomposition was found to be taking place after only 4 months in the soil capped pit. Without oxygen, the major breakdown product of decomposition is ammonium (NH₄⁺). In the presence of oxygen, nitrification occurs. This process is the breakdown of ammonium, first to nitrite (NO₂^-), then to nitrate (NO₃^-). Under the anaerobic conditions of the disposal pit, the ammonium concentration was found to be high in the upper 3 feet of the pit. No nitrates were found at lower depths due to lack of nitrification because of the absence of oxygen.

Due to the lack of samples taken in the first 4 to 6 weeks of the pit being capped, another pit was dug and measuring instruments added in October 1992. The pit is currently being filled and will be monitored as the first pit with the addition of earlier samples being taken and measured. Based on initial research, it is believed that burial pit disposal of cull onions does not contribute a nitrate leaching problem to groundwater under short-term conditions; however, it is believed that total decomposition of the onions takes 4 to 5 years. A follow-up proposal is being considered to continue to monitor both pits on a quarterly basis until onion dry-down occurs. It will then be possible to excavate the pit and take final samples.



WATER QUIZ ANSWERS


1. True	That's 1,350 gallons a month!
2. True	However, 50 percent of U.S. drinking water is from surface sources.
3. False	Don't buy products that say, "poisonous, toxic, corrosive," etc.
4. True
5. True	Heat can dissolve lead from pipes and solder into your water. New houses with lead-free solder are not as likely to have lead problems.
6. False	Giardiasis can be caused by animal wastes in remote untreated streams.
7. False	Contaminants can seep through the ground. Have your well tested for contaminants by your local health department.
8. True	It's called Xeriscape.
9. True	In some cities, the number of glasses can go as high as 15,000.
10. True	They can seep into the water underground or rain can wash them into surface water.
11. False	The U.S. government regulates quality and currently has standards for more than 80 contaminants.
12. True	Showers and toilets are the major users.
13. False
14. True	Even though some landfills have a protective lining, leakage can occur and contaminate groundwater.
15. True	Many are drilled to monitor water quality in aquifers and in areas around dump sites.
16. False	It wastes water.
17. False	We have identified or are using most water sources in the U.S.
18. False	All unused wells should be capped. Open wells can provide a route for contaminants to reach aquifers.
19. False	It's smart to save water no matter where you are.
20. True	Call your water utility company, speak up at public meetings, write a letter to your city council. You can affect decisions!



Comments to webmistress: karenl@uidaho.edu

All contents copyright © 1997-2003.
College of Agricultural and Life Sciences, University of Idaho.
All rights reserved.

Revised: January 3, 2003

URL: http://www.uidaho.edu/wq/wqu/wqu31.html