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:
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
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:
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:
DO YOU HAVE A DOMESTIC WATER QUALITY
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:
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.
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:
Research projects include work to:
Some of these efforts include:
RIPARIAN AREAS ARE
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:
NITRATE EFFECTS ON
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)
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
|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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All contents copyright © 1997-2003. College of Agricultural and Life Sciences, University of Idaho. All rights reserved. Revised: January 3, 2003