ARTICLE INDEX
Volume 4, Number 3
June 1994
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PROTECT YOUR WELLHEAD!
Why should you be concerned about your wellhead? Ninety-five percent of
rural residents in Idaho use groundwater obtained from private wells to supply
drinking water. Your well is your own private gold mine! Improperly constructed
and maintained wells can put both your family and the health of your pets
and/or livestock at risk.
Large areas that contain groundwater are called aquifers. Wells are drilled into aquifers that are found in many areas of Idaho. The water in aquifers is a finite resource. Without an aquifer containing potable water many of you could not live in a rural area. In effect, your well drilled into an aquifer provides you with independence! The contamination of drinking water obtained from your well could compromise this independence and perhaps even force you off your property.
Within a given geographic area many landowners obtain their drinking water from wells drilled into the same aquifer. In fact, it is not uncommon to find hundreds of rural wells drilled into the same aquifer. The prevention of well contamination should be your top priority because once contaminated, it becomes very difficult, if not impossible, to clean up the aquifers. Since the water produced from your well comes from the same underground body of water as your neighbor's well, if your well becomes contaminated your neighbor (and everyone else obtaining water from the same aquifer) may suffer the same fate.
To protect your well and its water quality you should use best management practices (BMPs), which are defined as implemented strategies that eliminate or minimize environmental pollution. BMPs are designed to be compatible with good, sound wellhead protection. BMPs can protect the environment and eliminate or minimize the threat of environmental pollution.
There are five major areas where BMP implementation should be considered. These
areas include:
Well location. The location of your well is a crucial factor determining the safety of your drinking water. Consider:
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WATER MANAGEMENT PATTERNS IN
SW IDAHO
Tim Stieber, University of Idaho Water Quality Agent, conducted a survey of
current water management practices in the Idaho Snake-Payette Hydrologic Unit
Water Quality Project (HUA). The Snake-Payette HUA comprises over 840,000 acres
in Canyon, Gem, Payette, and Washington counties in southwestern Idaho. Water
management is a key ingredient in the protection of surface and groundwaters.
Excessive water use can result in the movement of agrichemicals (pesticides and
nitrates) off the farm into surface waters or into groundwater via leaching.
This survey of grower irrigation management practices was a necessary first step for the development of both education and implementation plans related to irrigation in the HUA. Specific survey objectives included:
Thirty-five local fieldmen and representatives of 19 private companies actively participated in this survey. Data were collected by using both grower interviews and field records. The data collected in 1992 covered 13,000 acres of cropland, which represented 3.6 percent of the irrigated acres in the HUA.
Methods of water application. Irrigation is primarily accomplished by surface methods--both furrow and sprinkler systems are used. Furrow irrigation is dominant on 10 of the 12 crops surveyed in the HUA. Sprinkler irrigation is dominant in orchards and potato fields. Drip and micro irrigation methods are currently practiced on less than 1 percent of the HUA acreage.
Number of water applications. Crops in the HUA are irrigated anywhere from 3 to 14 times a season. In general, shallow rooted crops like onions and potatoes are irrigated more frequently than deeper rooted crops. The number of irrigations is also positively related to the length of growing season.
Amounts of water applied. The project area has a semi-arid continental climate with less than 4 inches of precipitation during a typical growing season. The warm, dry summers necessitate frequent irrigation to fulfill seasonal consumptive use of the crops grown in the HUA. The average amount of water applied to each crop was based on average reported irrigation plus rainfall during the 1991 growing season.
Crop | Average water applied | Crop consumptive use |
|---|---|---|
| ------------- (acre inches) ------------- | ||
| Alfalfa-hay | 40 | 32.3 |
| -seed | 19 | 16.4 |
| Bean-dry | 39 | 18.3 |
| Corn-field | 47 | 27.5 |
| -sweet | 46 | 17.9 |
| Hops | 40 | 19.2 |
| Mint | 52 | 26.1 |
| Onions | 50 | 19.6 |
| Orchards | 48 | 33.3 |
| Potatoes | 49 | 24.4 |
| Small grains | 39 | 16.0 |
| Sugarbeets | 56 | 29.8 |
Crop consumptive use values are based on evapotranspiration values from the USDA-SCS Idaho Irrigation Guide. Water applications range from 19 to 56 acre inches for HUA crops over the growing season. Actual crop consumptive use values are crop dependent and range from 16.0 acre inches of water for small grains to 33.3 acre inches of water for orchards.
Based on consumptive use, all crops received more water by irrigation than actually required by evapotranspiration. This excess ranged from 3 inches for alfalfa seed to over 30 inches for sweet corn production. Based on evapotranspiration values, sweet corn uses only 36.9 percent of the water applied in an average year (48.4 - 17.9 = 30.5). Crops using less than half the water applied include: potatoes (49.8%), hops (48%), dry beans (46.9%), small grains (41%), and onions (39.2%).
Total water use. Over 1,500,000 acre feet of water are annually applied in the HUA. Almost half of this water is applied to alfalfa and small grain crops. Sugarbeets and field corn also consume significant amounts of water.
Irrigation scheduling. The primary method for scheduling irrigations in the HUA was reported to be experience. Irrigation scheduling based on evapotranspiration and soil moisture monitoring provides an avenue to improve irrigation efficiency in the HUA. Fourteen percent of fields surveyed can only be irrigated when water is available to the grower.
Based on information gained from this survey, cost assistance programs and informational efforts are being targeted toward practices to improve the water use efficiency in the HUA. Practices being promoted to decrease deep percolation and runoff from surface systems include: surge irrigation, land-leveling, straw mulching, basin irrigation, improved scheduling methods, and tailwater re-use systems. A brochure on the results of this survey is available at no charge. Ordering information is provided on page 8 of this newsletter.
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GROUNDWATER--A ROLE IN
PLANNING AND DECISION MAKING?
Groundwater has often been slighted in water supply planning and management. For
a long time, it was believed that groundwater could not be as easily evaluated as
surface water, in terms of its availability, development, chemical quality, and
the economics of recovery. On the contrary, new hydrogeologic information and
understanding, along with substantial progress in analytical capability, have
improved the ability to plan, develop, and manage groundwater. Scientific
analysis of groundwater systems has opened the door to more effective,
organized use of groundwater, and to the development of more protective measures
from polluting activities.
Groundwater hydrology is an interdisciplinary mix of the physical, biological, and mathematical sciences. New concepts and methods have improved investigation and problem solution. Simulation methods developed within the past 25 years permit revealing model analysis of groundwater systems and their interconnections with surface water. Modeling enables prediction of the effects of pumping and waste disposal on groundwater. It also allows greater consideration of alternative management plans.
Inadequate communication between the groundwater expert and the planning expert is partly responsible for the lack of integration of groundwater into water resources planning. Closer affiliation of these experts is fostering increased mutual understanding of groundwater and its important role in national water supply. Groundwater is now recognized to be a fundamental component in the comprehensive joint management of land, water, and waste throughout the nation.
The magnitude and complexity of groundwater problems continue to
grow. For this reason, expanded efforts are needed to ensure
adequate groundwater data and information, and to bring
groundwater into the mainstream of planning, management, and
decision-making at all levels of government.
(Adapted from Groundwater and Public Policy. Series No. 1 by G. H. Davis,
Private Consultant)
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RECOMMENDATIONS TO PROTECT SOIL AND WATER
QUALITY
In a report issued late last fall, a National Research Council committee
concluded that new national policies and new approaches to farming are needed to
address soil and water problems attributed to farming practices.
The report said that efforts to protect soil quality deserve the same attention as those for air and water. Protecting soil quality should be a fundamental environmental goal for the nation, with increased attention to the prevention of surface and groundwater pollution through more effective use of fertilizers, pesticides, and irrigation.
The committee recommended that the USDA, EPA, and Congress undertake a coordinated effort to identify the highest priority regions for federal, state, and local programs to improve soil and water quality. Technical assistance, educational programs, financial resources, and government regulations should be directed at regions where degraded soils and polluted water are most severe, and at farms that cause a disproportionate amount of environmental problems.
According to the report, targeting measures to prevent soil degradation and water pollution now may allow U.S. agricultural producers to avoid high-cost solutions in the future. But time for low-cost solutions could be running out. "In some regions, soil degradation and water pollution may already be serious enough that solutions will entail economic losses to the agricultural sector," the committee cautioned. "Concerted action now is needed to prevent the list of such regions from getting longer."
Problem solving strategies. The committee defined four interrelated strategies for national policy that hold the most promise of preventing soil and water problems while sustaining farm profits.
1. Broadening the approach to protecting soil quality. "National policies to protect soil resources are too narrowly focused on controlling erosion and conserving soil productivity," the committee said. Other important and often irreversible threats to soil include salinization, compaction, acidification, and loss of biological activity. Soil is a living, dynamic substance that acts as the interface between agriculture and the environment. High-quality soils, for example, prevent water pollution by absorbing and partitioning rainfall and by breaking down agricultural chemicals, wastes, and other potential pollutants.
2. Increasing efficiency in the use of fertilizers, pesticides, and irrigation methods. Improving the way fertilizers, pesticides, and irrigation water are used can prevent pollution at its source. New programs are needed that reduce the amount of those potential pollutants produced as a by-product of farming. Many technologies and management methods are already available for more efficient use of fertilizers, pesticides, and irrigation water, but they need to be more widely implemented, the committee said.
3. Reducing farm erosion and runoff. Many different conservation systems such as reduced tillage, crop rotation, and use of cover crops have proven potential to reduce erosion and runoff. But today, only 30 percent of U.S. cropland are farmed using reduced tillage methods. In many regions, increased use of these techniques on lands that are most vulnerable to degradation of soil quality or that most contribute to water pollution could result in dramatic decreases in erosion and runoff.
4. Creating and protecting "buffer zones." In many watersheds, "field-by-field" efforts to conserve soil quality, increase efficiency, and reduce erosion and runoff will not be enough to protect the environment. Buffer zones, such as vegetation along streams; strategically planted grass strips; and sophisticated, artificially constructed wetlands can help intercept or immobilize pollutants and reduce runoff, the committee said. These zones can augment, though not replace, efforts to improve farm management. "Managing the landscape by creating or restoring buffer zones is a promising way to increase the effectiveness and lower the cost of programs to protect soil and water quality," the committee said.
Emphasis on one strategy to the exclusion of others could exacerbate one
environmental problem while attempting to solve another, the report warned.
(Adapted from EPA News-Notes, No. 35)
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GROUNDWATER POLLUTION
PREVENTION: VOLUNTARY BMPs FOR AGRICULTURE?
(This is the first in a series of articles on the potential effectiveness of
the voluntary approach to reducing agrichemicalcontamination of
groundwater.)
In considering the potential effectiveness of a voluntary approach to reducing
agrichemical contamination of groundwater, several questions need to be asked.
The answers to these questions will assist in determining whether a particular
environment is conducive to voluntary change.
It is becoming increasingly clear that the general public has identified agricultural chemicals as a major threat to groundwater quality. National studies of the general population, as well as local public opinion polls, place commercial nitrogen fertilizer and agricultural herbicides and insecticides at the heart of this concern.
The quantity of synthetic materials that agriculture introduces into the environment is great, and it is increasingly clear that residue from these materials is entering groundwater used for drinking water. The exact quantities, the ultimate health threat, and whether the problem is predominantly a point source or a nonpoint source concern are not fully clear. Certainly, variations in soil composition, chemical properties, and agronomic practices result in different levels of risk.
Although there are localized problem areas in many regions where agricultural pesticides have been documented in groundwater, such as in grain- and livestock-producing areas of the Midwest, concentrations generally have been below health-advisory levels. On the other hand, nitrate concentrations exceeding federal drinking water standards may be more widespread, at least as reflected in tests of water from private shallow wells.
Several public policy options exist for addressing groundwater contamination at the state level, including strong regulatory roles; public expenditures; and research, education, and demonstration. Ultimately, a combination of strategies with varying incentives and disincentives will likely evolve in many states.
Assessing a voluntary approach. If a voluntary approach is to be a viable option, three assessments--biophysical, economic, and social--need to be made.
Biophysical assessment. First is the question of whether alternative practices, if available and adopted, would bring a problem under control and provide long-term protection. Alternative practices would not necessarily mean total elimination of chemical products but rather using existing technology more prudently, such as refined nutrient management, banding herbicides, or greater use of rotations. Although agricultural management options may exist and refined practices would make incremental improvements in the effect on groundwater quality, the key question is whether these changes would be sufficient to reduce to acceptable levels the threat to groundwater posed by existing agricultural practices.
Economic assessment. A second assessment is that of the economic advantages and disadvantages of alternative practices. Differences exist between findings of the academic agricultural economics community and reports of on-farm research. When marketing new, more environmentally sound practices, the increased profit motive that existed--or was espoused--when chemical products were being widely adopted a generation ago may be too simplistic a model for a new era of decision-making.
Social assessment. The third assessment needed in reviewing the viability
of voluntary approaches is social acceptability, or the likelihood of farmers
adopting alternative practices. There are a number of factors that can contribute
to the likelihood of farmers voluntarily adopting alternative practices.
(Adapted from Groundwater and Public Policy. Series No 10 by
Steve Padgelt from Iowa State University)
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NEW PUBLICATIONS
The University of Idaho Cooperative Extension System has recently printed several
new water quality brochures. Copies of these brochures are available at no charge
from your local extension office. These new titles are:
| WQ-26 | Cropping Practices Survey--Water Management Results. Idaho Snake-Payette Rivers HUA |
| WQ-27 | BMPs for Erosion Control |
| WQ-28 | BMPs for Lawn Care in Idaho |
| WQ-29 | BMPs for Idaho Gardens |
| WQ-30 | BMPs for Wellhead Protection |
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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