ARTICLE INDEX
Volume 2, Number 3
June 1992

IDAHO'S AQUIFERS
Large areas that contain groundwater are called aquifers. Idaho has several aquifers that are essential to the state's water supply. Aquifers occur in either consolidated or unconsolidated ground formations. Consolidated aquifers hold water in the cracks of solid rock, and the amount of water available depends upon the size and number of cracks. Unconsolidated aquifers hold water in a mixture of sand and gravel. The Snake River aquifer in southern Idaho is an example of a consolidated aquifer, and the Rathdrum aquifer in northern Idaho is an example of an unconsolidated aquifer.

Another characteristic of aquifers is whether they are confined or unconfined. Confined aquifers have impermeable surfaces on the top and bottom. Being confined often puts the water under pressure and the groundwater will rise toward the land surface when the upper layer is pierced by a well. This is often referred to as an artesian well. Unconfined aquifers are not under pressure and the water table delineates the top of the aquifer. Idaho has both confined and unconfined aquifers throughout the state.

Idaho has three major aquifer types: (1) valley-filled, (2) basalt, and (3) sedimentary/volcanic aquifers. Valley-filled aquifers hold water in unconsolidated sedimentary material, usually in intermountain valleys. Basalt aquifers hold water in the cracks of underground rock (basalt), and in thin sedimentary layers that are interbedded with the basalt. Sedimentary/volcanic aquifers contain a mixture of unconsolidated sedimentary material, sedimentary rock (sandstone and shale), and basalt. Geothermal water is usually associated with sedimentary/volcanic aquifers.

Groundwater contamination can result both directly by injection of contaminates into the groundwater through wells, or when the ability of the soil to adsorb and immobilize or breakdown contaminants is exceeded. Under the latter conditions, contaminants applied at the land's surface move downward and may eventually reach the aquifer. For example, some wells in Idaho contain excessive levels of nitrates that may come from agricultural fertilizers, lawn and garden fertilizers, septic tanks, and/or livestock feeding operations.

The Idaho Department of Health and Welfare (IDHW), the Idaho Division of Environmental Quality (IDEQ), and the Idaho Department of Water Resources (IDWR) have prioritized major Idaho aquifers based on their vulnerability to pollution. Vulnerable areas exist where groundwater is shallow or where soils are thin or very permeable. Also, the potential for contamination is greater where considerable water is applied to the land surface from precipitiation or irrigation water, which can move contaminants below the root zone. Factors considered in the overall vulnerability ranking used by IDEQ and IDWR were population density (as a measure of land use) and intensity of groundwater use. The ranking of Idaho's most important aquifers (for location see map; numbers correspond to map) from most to least vulnerable is as follows:

1. Boise Valley
2. Snake River Plain
3. Rathdrum Prairie
4. Marsh Creek/Lower Portneuf
5. Salmon Falls Creek/Rock Creed
6. Payette Valley
7. Coeur d'Alene River Valley
8. Mountain Home Plateau
9. Moscow Basin
10. Clearwater Uplands and Plateau
11. Goose Creek/Golden Valley

The majority of the ongoing pollution prevention efforts in Idaho are targeted at the Boise Valley, Snake River Plain, and Rathdrum Prairie aquifer areas. Beginning with the next issue of WATER QUALITY UPDATE we will start examining each of the 11 aquifers one at a time (in order of state priority) in more detail.

BMPs FOR PHOSPHORUS MANAGEMENT
Phosphorus is essential to all forms of terrestrial life. Phosphorus is widely distributed over the surface of the earth in biologically available forms cycling within plants, animals, soil, and water.

Water is the lifeblood of Idaho. Over 22 billion gallons of water are used each day in Idaho. Because water is so vital to Idahoans best management practices (BMPs) for agricultural management have and are becoming more important. Phosphorus (P) is a common water pollutant in Idaho's lakes and rivers. Phosphorus originates from many sources including agriculture.

Water quality problems associated with P are generally confined to surface waters only. Phosphorus is immobile in soils and does not leach. Consequently, a contamination of groundwater is rarely a problem. The rest of this article discusses P as a surface water quality concern.

Many human activities contribute P to surface waters. Activities associated with modern agriculture often significantly increase water runoff from land and transport sediment into surface waters. Land enriched with P by fertilization or manure can contribute substantial amounts of P to surface waters as the result of runoff and/or erosional processes.

Phosphorus in fertilizers and manures will not leach through soils to pollute groundwater because it is held tightly to soil particles. However, soil particles that are transported off the field by erosion will pollute surface waters. Surface water pollution is controllable -- by reducing soil erosion and keeping soil out of creeks, streams, rivers, and lakes.

Specific types of BMPs for P fertilizer and manure management that should be employed to protect surface water quality in many areas of Idaho include:

1. Soil Erosion Control
2. Fertilizer Recommendations Based on Research and Soil Sampling
3. Correct P Fertilizer Placement
4. Variable Fertilizer Management
5. Efficient Manure Management
6. Barnyard and/or Feedlot Runoff Control
7. Conservation Tillage and Residue Management
8. Buffer (Filter) Strips

Numerous BMPs for the control of runoff and soil erosion are available. These practices have been shown to be effective in reducing contaminant transport to surface waters. Practices for runoff and soil erosion control include both management options and the building of physical structures. Management practices designed to control runoff and soil erosion are:

• Permanent vegetative cover
• Conservation cropping sequence (rotation)
• Conservation tillage and residue management
• Contour farming
• Strip cropping
• Cover crops
• Buffer (filter) strips
• Mulching

• Diversions
• Grade stabilization structures
• Grassed waterways
• Ponds
• Sediment basins
• Terraces

DO YOU HAVE A DOMESTIC WATER QUALITY PROBLEM?
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.

Consumer Tips on Treatment Devices. Water treatment devices should be carefully selected to correct specific undesirable characteristics. No one device can solve all water problems although compound treatment units are now being marketed that contain sets of treatment devices all housed in a single cabinet.

The household water treatment market is growing rapidly as people become more concerned with the quality of their water. The Federal Trade Commission (FTC) reports that water purifier fraud is also growing rapidly. Unscrupulous merchandisers are taking advantage of the demand by exaggerating the benefits of their products, by charging exorbitant prices, and by offering questionable incentives.

A few consumer tips to those who believe they might have water quality problems are:

1. Visit your public health officials or other unbiased water quality experts about your suspected problems. Inquire about specific things appropriate to test for.
2. Have your water tested for specific contaminants by an independent laboratory. Do not rely solely on tests performed by the seller.
3. Educate yourself on the limitations and disadvantages, as well as potential benefits, of specific treatment units.
4. Be wary of mail or telephone contacts offering solutions to your water quality problems.
5. Get a second opinion before purchasing an expensive water treatment system.

• the particular contaminant(s) the is(are) present
• the severity of the contamination
• the sources(s) of the contamination
• the uses for which the water is intended
• the individuals who will be using the water

1. Do nothing. If the contaminants do not present a health hazard or pose a particular threat to the water system you may rightfully choose to just "let it go." Examples might include a low to moderate water hardness problem or a slight intermittent turbidity problem.
2. Eliminate the source(s) of contamination. The most ideal solution, if possible and practical, is to identify and eliminate the source(s) of contamination. It is certainly preferable to prevent contamination rather than having to depend on its continuous removal by treatment facilities. Examples might include providing protection for the well head to prevent surface contamination from entering the well, deepening the well to a new unpolluted aquifer, or drilling a new well at a location better protected from contamination sources.
3. Install treatment facilities for the entire water supply. The presence of certain contaminants may warrant their removal from the entire household water supply. These contaminants are those that could pose a threat to people or pets or to the household water system regardless of the intended use of the water. Examples might include a sedimentation and filtration system to remove suspended materials, a chlorination system to control bacterial contamination, a neutralizing filter to control acid water, or periodic shock chlorination treatment to control iron bacteria.
4. Install treatment facilities only for water being used for specific purposes. With most water quality problems, it is practical to provide treatment only for those uses where treatment is appropriate. This practice lowers the investment, maintenance, and operational costs associated with the treatement facility. Examples might include hard water, odor, taste, or staining problems where only the water used inside the house is treated. Other examples appropriate as point-of-use (POU) facilities could include activated carbon filters for removing volatile organic chemicals and radon, reverse osmosis (RO) or distillation units to remove total dissolved solids and nitrates (particularly important for expectant mothers and infants), or ultraviolet units to kill microorganisms.
5. Purchase bottled water or otherwise haul water from a safe source. This alternative is used to obtain water for human consumption that is free of biological and chemical contaminants. It by-passes the need to have and maintain effective water treatment facilities capable of controlling health threatening contaminants.

PHOSPHATES IN DETERGENTS
The discussion over the use of phosphates in powdered laundry products has continued since the 1960s. In the 1990s, as environmental concerns become more and more intense, this discussion will continue among environmentally conscious consumers and manufacturers.

Phosphates are added to laundry detergents to improve or "build" their cleaning power. They are a popular ingredient in detergents because they are effective, reasonable in cost, and safe to use on appliances, fabrics, and humans.

Together with other naturally occurring nutrients such as carbon, nitrogen, and potassium, phosphorus nourishes algae and plants in lakes and streams. Phosphorus in the form of phosphate causes trouble when high levels lead to too many plants.

About 25 to 30 percent of the phosphorus in household wastewater comes from detergents. The rest comes from human waste and food waste. Detergents contribute 3 percent of the phosphorus entering United States surface waters annually.

One way legislators have dealt with local problems of plant growth in lakes and streams is to ban or restrict the amount of phosphate in laundry detergents. No federal regulation in the United States bans or restricts the levels of phosphate in laundry detergents.

The detergent industry has voluntarily reduced the level of phosphates in powdered detergents since 1970. The phosphate content of powdered detergents appears on the side panel in percentage and/or gram form. Some companies use codes to express phosphate content: 0 = no phosphate, L = limited phosphate, and P = high phosphate.

Automatic dishwashing detergents get daily use and perform their tasks well. The soap and detergent industries, however, are continually evaluating how much phosphate needs to be in these detergents. The amount of phosphorus in the form of phosphate used in automatic dishwashing detergents has decreased in the past 10 years.

Residual food and mineral films left on dishes after dishwashing can cause food spoilage and illness. To date, no state has banned phosphates in automatic dishwashing detergents. Where phosphates are regulated, the amount allowed is generally 8.7 percent phosphorus.

Scientists have been unable to find an acceptable substitute for phosphates in automatic dishwashing detergents. The soap and detergent industry will continue to search for alternatives to phosphates. However, any legislation that would arbitrarily force unrealistic limits on phosphates in automatic dishwashing products is not in the public interest.

For additional information on phosphates, you can get a copy of CIS 907, Phosphates in Detergents, at your local county Extension office.

WATER QUALITY RESEARCH
Over 30 faculty in the College of Agriculture are actively engaged in research projects targeted at water quality problems within the state and of national concern. These on-going research projects in the agricultural experiment station are conducted in every department in the college, on campus at Moscow, and at various Research and Extension Centers located throughout the state. The Agricultural Experiment Station (AES) maintains the University of Idaho Analytical Laboratory. This facility supports the research, teaching, and extension programs of the college. This laboratory is capable of performing nitrate and pesticide analyses. In addition, facilities of this laboratory support programs in waste management and hazardous wastes. Important water quality research areas in the college include:

• Pesticide Movement and Degradation in Soil and Water
• Nutrient Use Efficiency and Movement in Soil and Water
• Irrigation Management
• Bioremediation
• Aquatic Ecosystems
• Soil and Water Management and Conservation

Research projects include work to:

• Isolate microorganisms capable of breaking down agrichemicals when injected into a contaminated area
• Contain microorganisms after application to an aquifer or soil
• Enhance the effectiveness of microbial breakdown of contaminants
• Detoxify pesticide containers and waste disposal sites

Some of these efforts include:

• Improve nitrogen use efficiency of Idaho crops
• Evaluate management strategies to reduce nutrient and pesticide leaching and runoff into surface and groundwaters (nutrients are primarily from fertilizers)
• Develop biological control strategies as alternatives to pesticides

RIPARIAN AREAS ARE VALUABLE
Lands adjacent to rivers, streams, and creeks (moving water) where the vegetation is strongly influenced by the presence of water are called riparian areas. In the arid western United States riparian areas are the most important habitat for the majority of wildlife species even though these areas comprise less than one percent of the land area. The conditions of riparian areas influence the timing and quality of water produced and how the watershed functions.

Diversity of vegetation is an important characteristic of riparian areas in good condition. Woody and herbaceous plants slow flood flows and provide a protective blanket against the erosive force of water. The plant foliage shields the soil from wind and sunlight, which keeps soil temperatures low and reduces evaporation. These plants produce a variety of root systems that bind the soil and hold it in place. Riparian vegetation filters out sediment which builds streambanks and forms productive wet meadows and floodplains and reduces sedimentation of water supply and hydroelectric reservoirs.

Many riparian areas are considered wetlands. Because riparian areas are productive, and have a relatively gentle terrain, they attract a variety of human activities. Because of this man has greatly modified many riparian areas with activities including cultivation, road building, mining, urbanization, logging, livestock grazing, and the damming of rivers. These modifications are not without cost, however. A degraded riparian area may have the following characteristics:

• Little vegetation to protect and stabilize streambanks and shade the stream
• Lowered water table and saturated zone, reduced sub-surface water storage
• Warm water in summer and icing in winter
• Reduced or no summer streamflow
• Poor habitat for fish and other aquatic organisms
• Poor habitat for wildlife
• Reduced amount and quality of livestock forage

• Diverse vegetation and root systems protect/stabilize streambanks, stream shaded
• Elevated water table and saturated zone, increased subsurface water storage
• Cooler water in summer, reduced icing in winter
• Increased summer streamflow
• Improved habitat for fish and other aquatic organisms
• Improved habitat for wildlife
• Increased quantity and quality of livestock forage

NITRATE EFFECTS ON LIVESTOCK
Some farm animals are affected in the same way as human babies by high levels of nitrate in the water supply. Nitrate poisoning can occur in animals less than six months old. As with human babies they are susceptible to nitrate poisoning because their digestive systems contain baceria that convert nitrate (NO₃) to the toxic nitrite (NO₂). Excess nitrite inhibits the oxygen-carrying capacity of blood. Without treatment this problem can be fatal. After the age of six months the acidity of the digestive system increases and conversion of nitrate to nitrite no longer occurs, thus reducing livestock susceptibility to nitrate poisoning. Nitrate is present in feed as well as in water. Crops harvested after a drought are likely to contain relatively high concentrations of nitrate.

Cows, sheep, horses, baby chickens, and baby pigs have digestive systems that support bacteria that convert nitrate to nitrite, and they are likely susceptible to methemoglobinemia (nitrate poisoning). Symptoms include bluish or brownish discoloration of the mucous membranes or the areas around the mouth or eyes, sluggishness, lack of coordination, rapid hearbeat, frequent urination, labored breathing, and abortions. If diagnosed in time animals can fully recover.

Currently there is no regulatory drinking water standard for livestock. The 10 ppm NO₃-N standard used for human drinking water is safe for all animals, but research suggests that higher concentrations may be acceptable, depending on nitrate concentration in the diet. The U.S. Environmental Protection Agency has recommended that drinking water for livestock contain no more than 100 ppm nitrate-N, although most species can tolerate higher levels.
(Source: CES, Cornell University)

EXTENSION PUBLICATIONS
The University of Idaho Cooperative Extension System has available several publications on water quality topics important to Idahoans. Copies of these publications are available at no charge from your local county extension office. Current titles include:

CIS 861	Pesticide Handling Practices to Protect Groundwater
CIS 865	Pesticides and Their Movement in Soil and Water
CIS 872	Nitrate and Groundwater
CIS 873	Water Testing
CIS 874	Drinking Water Standards
CIS 887	Idaho's Water Resource
CIS 893	Household Water -- Dos and Don'ts
CIS 895	Laundry Detergents
CIS 900	Groundwater in Idaho
CIS 907	Phosphates in Detergents

Extension has also published a series of water quality brochures. These can also be obtained from your local county extension office. Current titles include:

WQ-1	Activities in Water Quality -- The Cooperative Extension System
WQ-2	Water Quality Programs in the College of Agriculture -- Education, Research, and Extension
WQ-3	Idaho Snake River Plain USDA Water Quality Demonstration Project
WQ-4	Idaho Snake-Payette Rivers USDA Water Quality Hydrologic Unit Project
WQ-5	Idaho Wellhead Sampling Program -- Twin Falls County
WQ-6	Idaho Wellhead Sampling Program -- Canyon County
WQ-7	Idaho Wellhead Sampling Program -- Payette and Gem Counties
WQ-8	Idaho Wellhead Sampling Program -- Ada County
WQ-9	Idaho Wellhead Sampling Program -- Cassia, Minidoka, and Jerome Counties
WQ-10	Idaho Wellhead Sampling Program -- Latah and Benewah Counties
WQ-11	Idaho Wellhead Sampling Program -- Bonner County
WQ-12	BMPs for N Management
WQ-13	Idaho Wellhead Sampling Program -- Bonneville County
WQ-14	BMPs for Pesticide Management
WQ-15	BMPs for Phosphorus Management

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