i. •
&EPA
United States Nitrogen Work Group 40 0/3-90/003
Environmental Protection PM-221 March 1991
Agency
Nitrogen Action Plan
HEADQUARTERS LIBRAfN
ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, O.C. 20460
Printed an Recycled Paper
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TABLE OF CONTENTS
EXECUTIVE SUMMARY 1
RECOMMENDATIONS 9
TECHNICAL APPENDIX 17
PROBLEM CHARACTERIZATION 18
Ecological Damages ....... 18
Direct Toxic Effects 18
Indirect Effects 19
Estuaries 21
Fresh Waters 23
US EPA Water Quality Standards 23
Air Quality 24
Acid Deposition 24
Stratospheric Ozone Depletion 25
Climate Change 25
Ozone 26
Human Health Risks 26
Methemoglobinemia 26
Reproductive and Developmental Effects ... 28
Effects of Chronic Exposure 28
Carcinogenic Effects 28
Pathways of Exposure 29
Individual Exposure 29
Drinking Water Exposure 31
Public Water Systems 31
Domestic Water Supplies 35
Ground Water 36
Ground and Surface Water Interconnection . . 38
Economic Risks to Agriculture 38
Welfare Effects 38
SOURCES OF NITROGENOUS COMPOUNDS 40
Nitrogen Cycle 40
Nitrate Mass Balance 42
Natural Background Levels 43
Use of Isotopes to Identify Sources .... 43
AGRICULTURAL SOURCES 44
Commercial Fertilizer ........... 44
National Usage 45
Application Rates 45
Potential Hotspots for Fertilizer Use . 49
Irrigation 49
Chemigation 51
Drainage 52
Timing 53
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Livestock Waste 53
Concentrated Livestock Production ... 56
Animal Waste Storage Ponds 57
Abandoned Feedlots 57
Nonpoint Source Surface Runoff From
Fields 60
Legumes and Green Manures ......... 60
Greenhouses and Nurseries 60
Agri-Chemical Dealers 61
NON-AGRICULTURAL SOURCES 62
Septic Systems 62
Urban Sewage 64
Land Application of Sewage Sludge 66
Non-Farm Use of Fertilizer 67
Golf Courses 67
Airborne Sources 68
Industrial Sources 69
Food Processing Wastes 69
Other Industrial Sources 70
POLLUTION PREVENTION 72
AGRICULTURE 72
Management Practices for Commercial Fertilizer . 74
Timing 74
Nitrogen Soil Tests 75
Economically and Environmentally Optimum Use
Rates 76
Other Nitrogen Management BMPs 77
Soil Conservation 77
Irrigation and Drainage Management . . 78
Change in Cropping Patterns 79
Ground Cover 79
Nitrogen Inhibitors 80
Implementation Issues 80
Incentives 81
Technology Development and Education . 81
Taxes and User Fees 82
Reducing Price Distortions from Farm
Programs 82
Regulation of Fertilizer Use 82
State Programs 82
Toxic Substances Control Act 84
Agricultural Drainage Wells 85
Nurseries and Greenhouses 86
Livestock Waste Management 87
Concentrated Livestock Facilities 87
Surface Water Runoff from Fields 88
Ground Water 89
Implementation Issues 90
NPDES Program 90
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Policies Regarding Farm or Regional
Manure Surpluses 90
Runoff and Infiltration from Land
Application of Properly Stored
Livestock Wastes 91
Regulatory Programs 91
Incentive-Based Programs 92
Composting 92
Agri-Chemical Dealers 93
European Programs 93
Nitrate Policies in the European Community . 94
Programs of Key Individual Member States . . 95
The United Kingdom 95
West Germany 96
France 97
The Netherlands 97
Septic Systems 98
Regulation 100
Urban Sewage 101
Regulation and Treatment 101
Land Application of Sewage Sludge 101
Water Conservation 102
Industrial sources 103
Food Processing Wastes 103
Non—Farm Use of Fertilizer 103
Home and Commercial Site Lawns 103
Golf Courses 105
REMEDIATION AND TREATMENT 106
Public Water Systems 106
Monitoring 106
Public Notification 107
Treatment options 107
New Nitrate Removal Technologies 108
Enforcement 109
Domestic Drinking water supplies 110
Private Treatment Options 112
Bottled Water 113
US Department of Agriculture 114
Aquifer Remediation 114
INSTITUTIONAL ISSUES 116
Federal Government 116
Environmental Protection Agency 116
U.S. Department of Agriculture 119
U.S. Geological Survey 120
Tennessee Valley Authority 122
State Governments 122
Regional or Cross-Jurlsdictional Efforts .... 124
Local Governments & Others 126
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APPENDIX A—Acronyms Used 128
APPENDIX B~Glossary 130
APPENDIX C—Agency Responsibilities 132
APPENDIX D—Methodology for County-Level Manure
Estimates 133
APPENDIX E—Fertilization Rates in Major Producing
States 137
APPENDIX F—Tons of Nutrient N Sold By State 137
BIBLIOGRAPHY 138
TABLES
TABLE 1A
NUMBER OF ANIMALS IN INVENTORY IN 1987 (1,000'S) 54
TABLE IB
PRODUCTION OF MANURE AND NITROGEN PER ANIMAL AND NATIONAL
PRODUCTION TOTALS (1987): 55
TABLE 1C
LARGE-SCALE LIVESTOCK (PERCENTAGE OF TOTAL PRODUCTION): 1987 56
TABLE 2
Average N use on corn, all farms/split application farms. . . 75
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Figure 1 -
Figure 2a-
Figure 2b-
Figure 3 -
Figure 4 -
Figure 5 -
Figure 6 -
Figure 7 -
Figure 8 -
Figure 9 —
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LIST OF FIGURES
- Estuarine Systems Degraded by Nitrogen Loadings. . .22
— Human Exposure to Nitrate 30
— Human Exposure to Nitrite 32
- Public Water Systems: Violation of Nitrate MCL. . . 34
— Distibution of Nitrate-N Concentrations in Well Water
Samples 37
- The Nitrogen Cycle 41
- Commercial Nitrogen Fertilizer Sales 46
- Sales of N by Region 46
- Nitrogen Application Rates, Selected Crops 47
- Estimated Consumption of Nitrogen, Selected Crops. . 47
— Comercial Fertilizer Nitrogen Purchased per Acre of
Fertilized Cropland 50
Figure 11— Manure Nitrogen Availability per Acre of Fertilized
Cropland 58
Figure 12— Total Commercial Fertilizer and Manure Nitrogen
Availability per Acre of Fertilized Cropland 59
Figure 13— Density of Housing Units Using Septic Systems. ... 63
Figure 14— Septic System Operation 65
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NITROGEN ACTION PLAN EXECUTIVE SUMMARY
Nitrogen is an essential element for all living organisms. It
is continually being transferred between soil, water, air, and
biota in processes collectively known as the Nitrogen Cycle.
Nitrogen compounds are ubiquitous. Although they are found
naturally in the environment, a wide range of anthropogenic sources
of these compounds (primarily fertilizers, manure, septic systems,
waste water treatment plants, industry, and automobiles) increase
loadings to surface and ground water to levels that can be
hazardous to ecosystems and human health. This plan is chiefly
concerned with the risks from nitrate (N03) , nitrite (NO2), ammonia
(NH3) , and nitrogen oxides (NOX) .
Nitrate of natural or anthropogenic origin is found in all
surface waters and ground waters of the United States. It has many
important environmental effects, usually beneficial, but sometimes
adverse. Monitoring efforts by Federal and State agencies have
detected elevated nitrate levels in the waters of all 50 states.
Since complex factors determine whether or not nitrate will reach
surface or ground water (i.e., soil composition, geology, climate,
agricultural practices, cover crops), it is difficult to make
general predictions that a particular agricultural or disposal
practice will result in increased nitrate concentrations,
particularly in ground water.
Once contaminated, natural removal of nitrate from aquifers is
usually an extremely long-term expensive process, and remediation
is generally not practical or possible. Consequently, EPA's
Nitrogen Action Plan is grounded in the basic tenets of pollution
prevention: it is better to release fewer of these nitrogen
compounds into the environment and it is better to use practices
which minimize the movement of nitrate to surface and ground water
than attempt a costly remediation.
Effectively protecting the environment from excessive releases
of nitrogen compounds will require the concerted effort of multiple
interests and institutions: private citizens; environmental groups;
industry; agriculture; educational institutions; and local, state,
and Federal agencies. It will require a blend of education,
technology transfer and demonstration, regulation, and economic
incentive/disincentive tools.
RISK CHARACTERIZATION
Ecological Effects Toxic concentrations of ammonia are one of the
leading causes of fish kills. However, there appears to be no
direct human health threat from levels of ammonia typically found
in water. Fish kills from ammonia are generally transitory, since
ammonia is readily oxidized to nitrate.
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Nitrate is not directly toxic to aquatic life except at very
high concentrations [over 90 milligrams per liter (mg/L)1], but
excessive loadings of nutrients (nitrogen and phosphorus) may
promote eutrophication. Excessive nitrate, at levels an order of
magnitude below the level set to protect human health, appears to
be the principal cause of eutrophication of estuaries. Fresh water
bodies are more likely to be affected by phosphorus, although
nitrate is a factor in the degradation of some lakes and streams.
Nitrogen enrichment in estuaries can stimulate the growth of
algae, and possibly algal species that are less desirable as a food
source. Overabundance of algae can block sunlight from reaching
submerged aquatic vegetation, create excessive oxygen demand as it
dies off, and increase the incidence of toxic tides from algal
blooms. High nitrogen loadings can also upset the distribution of
species in an ecosystem by disrupting the food chain.
Estuaries all along the East Coast (ex: Chesapeake Bay, Upper
Potomac River Basin, New York Bight, Pamlico Sound) have been
adversely affected by nitrogen, as well as Puget Sound in the West
and several others on the Gulf Coast. Nitrogen inputs to marine
waters, as well as to many lakes and streams, including the Great
Lakes, are increasing.
Nitrogen is often a major contributor to acidity in sensitive
surface waters. These episodes can be lethal to individual fish
and invertebrates.
Human Exposure Nitrate is the most common chemical found by
drinking water surveys. Based on results from the National
Pesticide Survey, EPA estimates that more than 50 percent of both
public and private drinking water wells in the United States have
detectable levels of nitrate. 1.2 percent of public and 2.4
percent of private drinking water wells are estimated to have
nitrate at levels that exceed 10 mg/L, the Maximum Contaminant
Level (MCL). Some states have found a much greater percentage of
nitrate above 10 mg/L in private wells, for example: Iowa, 18%;
Nebraska, 17.5%; and Kansas, 28%.
Approximately 1.7 million people who use both surface and
ground water public water systems are exposed to nitrate levels
above the MCL during all or part of the year. In addition, perhaps
two million people who rely on private wells may also be drinking
water contaminated at levels above the MCL.
Human exposure to nitrate in drinking water could increase
1A11 nitrate measurements in this report will be expressed as
nitrate-nitrogen.
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substantially over the next few decades as a result of historic
increases in nitrogen loadings to the soil. Fertilizer sales have
quadrupled since the 1950s. Nitrogen that is applied to the
surface as fertilizer may reach the ground water as nitrate in
months or centuries depending on climate, soil, geology, and many
other factors.
Human Health Nitrate in drinking water at levels above the MCL
can cause methemoglobinemia ("blue baby syndrome") in infants under
six months. Even though doctors are not required to report this
disease, 2,000 cases are cited in the literature in North America
and Western Europe between 1945 and 1971 with seven to eight
percent fatalities. This rare, but potentially fatal disease,
limits the oxygen carrying ability of the blood. Older children
and adults do not show any acute effects at levels several times
higher than the MCL.
A few studies have investigated the possible reproductive
effects of nitrate with conflicting results. Developmental effects
have not been investigated with respect to humans. Currently
available evidence does not support reproductive and developmental
effects at levels below the MCL.
A greater number of studies have examined the possibility of
a correlation between nitrate intake and cancer. The National
Academy of Sciences (1981) stated that the association is plausible
because of the reduction of nitrate to nitrite in the human body
and the ability of nitrite to combine with secondary amines, found
in many foods, to form N-nitroso compounds which are potent
carcinogens. However, no association has been proven between human
exposure to nitrate in drinking water and increased cancer risk.
As a result of the uncertainties associated with the health
effects of nitrate and nitrite, it is not possible to quantify the
risks from these chemicals on a national basis.
Welfare Effects High nitrate levels in ground and surface water
can lead to adverse effects in areas other than human health or
ecosystems. Ruminant animals are susceptible to nitrate/nitrite
toxicity generally at levels of 100 mg/1 and above. Nitrate
contamination is the major cause of the closure of public wells.
In California, nitrate contamination has caused the abandonment of
more drinking water wells than any other chemical. Increases in
algal growth and blooms create conditions highly unfavorable to
recreation in surface waters.
SOURCES
There are many important sources of nitrogen compounds. It is
difficult to identify any single anthropogenic source as being
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generally responsible for the elevated nitrate concentrations in
ground and surface waters across the United States. The relative
importance of individual sources varies greatly from place to
place, depending on many factors including: land use, geology,
agricultural systems, climate, aerial deposition, intensity of
human activity, and the characteristics of a specific water body.
Ranking of sources of nitrate contamination is greatly complicated
by the fact that nitrogen in various forms may remain in the soil
system below the root zone for years or decades. The distribution
of nitrogen in the deep soil profile in sub-humid areas often
depends on historical practices. Generalization at the national
level, therefore, can only be a point of departure for analysis at
the regional or local level. With this in mind, the following
pieces of the picture emerge.
Nitrate naturally found in ground water is ordinarily three
parts per million or less. While instances do exist of naturally
occurring nitrate concentrations in ground water above the HCL,
these are exceptional cases. Widespread nitrate levels exceeding
the MCL are undoubtedly a result of anthropogenic impacts in humid
regions. Some areas have had human activity for so long it is
impossible to discern any natural background level. Where
background levels do occur, control of anthropogenic sources is
even more critical because the system has less ability to deal with
loadings in a benign way.
The fertilization of cropland has significant potential to
lead to nitrate contamination in many areas of the country.
Nitrate contamination of ground water from cropland is most likely
to occur in areas with coarse-textured soils and a shallow depth to
the water table, sinkholes (karst geology), or fractured bedrock.
Surficial aquifers with high recharge rates are the most vulnerable
to contamination. However, deeper aquifers may be increasingly
affected in the future. Commercial fertilizer is the largest
component of introduced nitrogen on cereal crops, followed by
fixation of atmospheric nitrogen by legumes, decomposition of crop
residues, manure, and atmospheric deposition.
Commercial fertilizer use is considered to be the major cause
of nitrate contamination in a number of Illinois watersheds.
Rising levels of nitrate in drinking water supplies in some area of
Iowa since 1950 have been attributed primarily to nitrogen
fertilizers. Fertilizer use in irrigated agriculture has been
identified as the chief source of nitrate contamination of ground
water in the agricultural valleys of California, Central Nebraska,
eastern Colorado, and in the sand plain region of central
Wisconsin.
Some researchers have indicated that farmers in some
circumstances apply commercial fertilizers at rates in excess of
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what is cost-effective. Many reasons have been cited for this
apparent irrational behavior: insurance against weather
variability; failure to adjust application rates to account for
nitrogen supplied by manure, sludge, or legumes; lack of adequate
soil and plant tissue tests; and failure to follow the best
available recommendations. Unrealistic yield goals are another
possible cause of excess application. Manure used as a nutrient
poses particular problems since it has a variable nitrogen content
and can be difficult for farmer to get accurately tested and to
handle, making environmentally sound application costly.
Both large livestock and dairy operations and the cumulative
output of many smaller operations in any given locale can also be
a major threat to water quality. Dairy operations, particularly
when they involve importing feed grains, represent significant
nitrogen loadings to the soil system. High levels of soil nitrate,
for instance, have been found beneath animal holding areas in the
dairy regions of southern California. Poultry manure, which has a
high nitrogen content, has been found to be a source of
contamination in areas of Arkansas and the Delmarva peninsula.
Abandoned feedlots, especially, are likely to leach nitrates.
Livestock manure has been cited as a major source of nitrogen
loadings to the Chesapeake Bay.
Any livestock operation, even one with manure management
facilities, can seriously degrade water quality, unless adequate
provisions are made for manure management. Cattle feedlots with
impermeable manure containment structures can pose a problem when
the structures have inadequate capacity and allow runoff. Some
farmers spread excess manure on land to dispose of it at rates that
can cause contamination of ground and surface water.
Non-agricultural sources of nitrogen compounds are significant
threats to water quality in many areas of the country. Septic
systems have been identified by 41 states as a major source of
ground water contamination. Septic systems are not designed to
remove nitrogen. They deliver organic nitrogen to soils at a point
below the root zone, thereby enhancing the chances that it will
leach as nitrate rather than be consumed by plants. Septic system
density is the best available indicator of a problem. The greatest
concentration of septic systems is found in the Northeast and
Middle Atlantic states. Individual septic system siting in
relation to drinking water wells is also an important
consideration.
Wastewater treatment plants and industrial facilities
discharge large quantities of nitrogen compounds directly into
water bodies. Secondary treatment at these facilities removes less
than half of the nitrogen from the effluent. In wet weather, many
cities with combined sewer overflows are forced to discharge
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effluent directly into water bodies with little treatment.
Industries and automobiles also discharge large amounts of
nitrous oxides into the air. These have been implicated in all
major air problems: acid rain, stratospheric ozone depletion, and
ozone formation in the lower atmosphere. Atmospheric deposition of
nitrate and ammonia are believed to account for about one-third of
the total input of nitrogen to the Chesapeake Bay. Estimates show
that the atmosphere is likely to be an important source of nitrogen
in some other estuaries as well as the Great Lakes.
Urban and suburban land uses such as for lawns and golf
courses contribute to nitrate loadings to ground and surface water
in areas where high rates of fertilizer are combined with improper
irrigation. These land uses can be responsible for significant
quantities of nutrient runoff during storms.
POLLUTION PREVENTION
Pollution prevention generally is the preferred approach for
addressing ground and surface water pollution problems. More
sustainable nitrogen management practices are necessary for all
sectors: agricultural, suburban, and urban. More costly remedies
should be focused on the largest sources in high risk areas.
Several nutrient management practices are available to reduce
farmers reliance on adding fertilizer nitrogen in excess of crop
needs. Better soil testing and timing of applications to meet
plant N requirements are practices recommended most often, although
insufficient resources for soil test calibration and interpretation
have limited the availability of soil tests capable of reducing
fertilizer use.
Related practices involve the setting of more realistic crop
yield goals, plant tissue testing for nitrogen, manure testing,
irrigation water testing for nitrogen, more efficient water use on
irrigated land, closing drainage outlets in winter on drained land,
winter cover crops, and establishing vegetative filters along
streams.
Preventing pollution on farms with livestock or dairy
operations presents additional challenges. The first prevention
measure which a farmer should undertake is the construction of
adequate manure storage facilities to limit unnecessary runoff.
Second, soil and manure testing, as well as calibration of manure
spreaders, are recommended to avoid applying manure at rates which
are greater than needed by the crop. However, limited financial
and managerial resources, as well as time constraints can undermine
proper manure management. Other major limitations to efficient
manure use include: the inability to correctly determine nutrient
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content; variability in nutrient content of manure; and the lack of
knowledge about the extent of nutrient release during growing
season, local and county-wide imbalances resulting from large-scale
livestock production between the production of manure and its use,
composting or de-watering, and transporting it to manure deficit
areas has to be considered. Uses may include land application,
feed supplements, and energy production. Testing of the feed is
also recommended to ensure that only appropriate levels of protein
are supplied.
Effluent from sewage treatment plants can be treated through
biological denitrification. While this process is expensive, it
may be necessary to protect valuable estuaries. With proper
management, wastewater and sludge can be applied to land to utilize
the nutrient value.
Since there currently are no economically practical methods to
limit nitrate concentrations in effluent from septic systems, they
should be regulated through siting requirements and zoning
densities to provide adequate area for dilution or provide
incentives for tie-in to sewer systems.
Golf courses and homeowners should adopt sustainable practices
in maintaining their lawns, such as leaving mowed clippings on the
ground and recycling nitrogen from the clippings back into the soil
to reduce the need for commercial fertilizer applications. Leaving
the mowed clippings on the soil should also result in improved
water-use-efficiency.
TREATMENT AND REMEDIATION
Where pollution prevention strategies have not been
implemented or are inadequate to prevent nitrate contamination of
water, nitrate levels in drinking water can be reduced to protect
public health. Nitrate removal from ground water or surface water
occurs naturally through the denitrification process in anaerobic
environments. No practical method has yet been found to reduce
nitrate levels in the aquifer, although researchers are now
experimenting with processes to augment denitrification, as well as
determining where denitrification is important in the subsurface
system.
Although nitrate can be successfully removed from drinking
water supplies, water treatment is an expensive process. A public
water system might be able to save the cost of treatment if it can
find a source of low nitrate water to blend with or replace its
current supply. When that is not possible, the water must be
treated to meet the federal drinking water standard. EPA currently
lists three technologies for adequate removal of nitrate from
public water systems: ion exchange, reverse osmosis, and
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electrodialysis.
EPA estimates that public water systems will have to spend
$192 million annually over the next 20 years to meet the nitrate
drinking water standard. Since most systems that violate the
standard serve small populations, most of the national costs will
be born by small public water systems which are least able to
afford the cost of treatment.
Private well owners with high nitrate levels can choose among
several options, depending on the cost of the options, the level
and type of contamination, and the amount of water the well owner
wants to be potable. They can continue drinking high nitrate
water, use bottled water, drill new or deeper wells, or install
treatment devices to remove nitrate. Bottled water has generally
been found to be free of nitrate, although testing procedures need
to be strengthened by the Food and Drug Administration. New or
deeper wells may only be a temporary solution because nitrate
levels in deeper aquifers many increase with time.
Very few States have formal programs for dealing with private
water supplies, although most will recommend laboratories for
testing. Construction codes, licensing of well drillers, and
siting requirements for new wells have been developed by some
States. Banks in several states have begun to require that well
water is tested for nitrate and bacteria, before loan approval.
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NITROGEN ACTION PLAN RECOMMENDATIONS
The Nitrogen Action Plan workgroup's recommendations are
organized into five categories. 1) develop State Nutrient
Management Programs, 2) improve on-farm nitrogen management to
protect water quality, 3) improve public and private drinking
water quality, 4) increase control of point sources through
current regulatory authority, and 5) research in areas of
uncertainty. These recommendations are not ranked in any order of
importance. They are all equally part of the plan.
EPA would ensure implementation of the recommendations through
three basic approaches: direct EPA action, nonregulatory and
regulatory; EPA encouraging or requiring State action; and EPA
working with the U.S. Department of Agriculture (USDA) and other
Federal agencies. The Nitrogen Action Plan would be implemented in
two phases. Phase I emphasizes using current regulatory
authorities, pollution prevention techniques, and research.
Activities under Phase II would begin if these voluntary efforts
and current legal authorities were insufficient.
Direct Agency Action
Under Phase I, EPA would use portions of the Safe Drinking
Water Act (SDWA), Clean Water Act (CWA), and Toxic Substances
Control Act (TSCA), Coastal Zone Management Act (CZMA) to implement
the recommendations. Although the authority is present for most
recommendations, additional money or reorientation of current
resources is necessary in many programs. Direct EPA action is
required to some degree in order to implement recommendations in
each of the five categories. Phase II recommendations would all be
implemented under increased EPA authority.
State Action
States that rank sources of nitrogen compounds as major
sources of ground or surface water contamination in their
assessments would develop programs that adequately address those
sources both from a pollution prevention and a drinking water
remediation perspective. EPA will work with the states through
guidance, grant agreements, and technical assistance to implement
the Nitrogen Action Plan recommendations.
Many of the actions address surface water contamination by
nitrogen compounds would be implemented by the States under the
§319 nonpoint source program of the CWA. EPA guidance under the
Coastal Zone Management Act will include many of these
recommendations. § 319 grant monies for implementing these actions
can be used as incentives for State participation by adding
nitrogen management as a rating factor in grant guidance, although
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this may require additional appropriations. If states have
pesticide management plans, this will be coordinated with their
nutrient management programs.
The recommendations that address ground water will be
implemented under, or in coordination with Comprehensive state
Ground-Water Protection Programs (CSGWPPs) and §319 Nonpoint Source
Programs.
Other Federal Agencies
EPA will work in close cooperation with the USDA, USGS, and
TVA (National Fertilizer and Environmental Research Center) to
implement many of the recommendations. Recommendation #2 would be
implemented through USDA programs. Under Phase I, we propose that
EPA form a workgroup with USDA to develop and implement and
programs that will improve fertilizer, manure, and feed management
to protect water quality. Some of the recommendations could also
be promoted formally through memoranda of understanding, intra and
inter-agency research initiatives. Coordinated research is
essential.
EPA also has an interest in working with USDA on drinking
water issues in recommendation #3 since Cooperative Extension
Service agents work with private well owners and Farmer's Home
Administration provides loan guarantees and makes grants to small
community drinking water systems.
Phase I
l. State Nutrient Management Programs
EPA will include nitrogen-related problems among those
considered for action under Nonpoint Source Programs, State
Comprehensive Ground-Water Protection Programs, Wellhead Protection
Programs, Pesticide Management Plans, and Coastal Zone Management
Plans. To maintain eligibility for EPA grants, Sates would be
required to consider and identify nitrogen-related problems for
action under these programs. States would then implement nutrient
management activities within these programs to prevent further
water quality degradation from nitrates and related compounds. EPA
will provide technical assistance documents, guidance on
development and implementation of nutrient management programs, and
grant guidance documents to the States.
State Program Elements;
1.1 Identify high risk watersheds through §319 (including
locations where ground-discharge significantly affects
surface water quality) and vulnerable wellhead areas.
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2. Farm Nitrogen Management
Through the Presidents' Water Quality Initiative (WQI), the 1990
Farm Bill, EPA's Agriculture Policy Committee and other forums, EPA
will collaborate with USDA to develop and implement voluntary,
cost-share best management practices (BMPs) that will improve the
efficiency of fertilizer use.
2.1 Assist USDA in its accelerated program to calibrate and
implement soil and manure tests.
2.2 Encourage and expand recordkeeping (realistic yield goals,
fertilizer application; yields; ; manure, sludge, food
processing residue, N tests); include soil tests when
available.
2.3 Expand Water Quality Initiative cost-share monies for
appropriate manure lagoon liners and storage facilities,
on-farm biomethanation plants, composting systems, manure
spreaders, etc. where cost effective. Assess and revise
existing SCS specifications to assure efficient use of
federal resources in constructing storage facilities.
2.4 Support financial incentives for vegetative filters (CRP,
WQIP, ACP).
2.5 Encourage the Soil Conservation Service to modify its
national standard for earthen manure ponds to require
liners to protect ground water in high risk areas.
2.6 Encourage USDA to offer easements to retire cropping rights
within Wellhead Protection Areas by using the Environmental
Easement Program in the 1990 Farm Bill.
3.
Remediation and Treatment
EPA will work with state, federal, and private agencies to
improve the guality of public and private drinking water supplies.
Some actions can be taken by EPA through current authority under
the Safe Drinking Water Act (SDWA). Other recommendations will
require collaboration and cooperation, rather than regulation.
Public Water Supply
3.1 Increase federal and State enforcement actions against
public water systems with violations of the nitrate
standard set under the SDWA.
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3.2 Require development of enforceable limits on fertilizer
use (and other nitrogen inputs) in wellhead protection
areas established under the SDWA and provision of bottled
water to infants in return for exemptions from the MCL
for small public water systems with nitrate violations.
3.3 Encourage States to develop innovative funding (tax, fee
on sources of nitrogen, etc.) to assist public water
systems and domestic well owners to treat water, provide
an alternate source, or buy easements.
3.4 EPA to enter into a Memorandum Of Understanding with the
Food and Drug Administration to require bottled water
companies to monitor at the same frequency as Public
Water Supplies and for the same contaminants.
3.5 Encourage States to develop wellhead protection programs
to protect public wells from all sources of contamination
as required under §1428 of the SDWA.
3.6 Pursue adoption of requirements for wellhead protection
where public wells are financed by Federal or State
grants or loans (e.g., FmHA).
Domestic Water Supply
3.7 Encourage States to implement specific action to protect
private wells, i.e. well construction codes, well driller
certification, well testing requirements, sanitary
surveys, financial aid, alternative water (infants and
pregnant women), septic system siting, and land use
restrictions to protect water quality. Many of these
actions will be necessary in order for a state to meet
the required elements of a SCGWPP.
3.8 Encourage States/lending agencies to require well testing
before real estate transfers and for new wells.
3.9 Encourage states to consider adopting the approaches used
under their Wellhead Protection Programs for public water
wells to protect densely-settled areas relying on
geographically clustered private wells.
4. Point Source Control/Management
This recommendation focuses on using EPA's current regulatory
authority under the Clean Water Act (CWA), the Safe Drinking Water
Act (CWA), and the Toxic Substances Control Act (TSCA) more
effectively to deal with sources of nitrate contamination.
Some additional authority would also be required.
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4.1 Under the Class V well underground injection control
program of the SDWA, require BMPs on cropland and
greenhouses that are drained by agricultural drainage
wells.
4.2 Require water quality based permits for feedlots and
greenhouses. strengthen NPDES permitting for feedlots
regulated under CWA authority. Include a land
application and manure storage component protective of
surface and ground water in permits.
4.3 Require anti-backsiphoning devices on fertigation
systems.
4.4 Revise the CWA to eliminate the point source exemption
for irrigation return flows so that EPA can target those
categories of flows or geographic areas with the greatest
potential for serious environmental damage.
4.5 Under TSCA authorities consider using the product
stewardship to require fertilizer manufacturers to
develop programs on proper handling and use of
fertilizers. Begin a regulatory investigation on
requiring fertilizer dealerships to store and handle
fertilizer to better protect water quality.
4.6 Move up the timetable in the Water Quality standards
Framework to develop nutrient guidance for water quality
standards by 1993.
4.7 Add a requirement to the EPA Operating Guidance that
during a State's triennial review, the State adopt
numeric ammonia standards for water where designated uses
are impaired due to ammonia. Encourage adoption of
State-wide standards.
5. Research
In order to better understand the risks of nitrogen compounds
and effective ways to deal with these risks, research must
continue. These recommendations identify key areas where more
research is needed either by EPA or through increased coordination
with other Federal agencies. Adoption of particular
recommendations may depend on predictions of future contamination
of shallow or deep aquifers.
5.1 Fill in data gaps on health effects using a TSCA test
rule or EPA/other Federal agency funds.
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5.2 EPA along with other Federal agencies such as USGS, USDA,
and NOAA should work to jointly improve understanding of
fate and transport, including aerial deposition, nitrogen
soil loadings, and waste load allocations in surface
waters. Plans should be developed on a land use by land
use basis including intensively managed crop lands and
unmanaged forest ecosystems to identify the processes
most important in determining the environmental
processing of nitrogen. The plans would include the
consideration of:
in situ denitrification rates and mechanisms in the
saturated zone and below the root zone in the
unsaturated zone.
- fate and transport modeling in the saturated zone
and below the root zone.
estimates of the depth and age of nitrate
contamination of the saturated zone and predictions
of peak contaminant levels in deep aquifers under
several nitrate management scenarios
determine the benefits of adding organic matter to
the soil
fate and transport modeling in soil with emphasis
on computing N mass balance and transformation
rates
5.3 Develop new technologies and improve existing
technologies for water supply and wastewater treatment.
Improve efficiency of drinking water treatment to
reduce costs, especially for small systems.
Improve wastewater technology, including use of
constructed wetlands.
- Develop/evaluate alternative septic tank designs.
5.4 Research to improve manure management:
USDA to research cost-effectiveness of innovative
manure and septage uses and distribution, for areas
in which land area suitable for application is
limited.
Evaluate the nutrient content of manure and how it
changes over time in relation to the ability of the
plant to take up N.
5.5 Evaluate the effectiveness, i.e., risk communication,
economic efficiency, financial impacts, health and
environmental efficacy of implementing the Nitrogen
Action Plan.
5.6 Work with USDA to evaluate effectiveness of nutrient best
management practices for water quality, including ground-
water discharge into surface water.
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5.7 Determine where economically efficient application of
fertilizers and manures will still adversely affect water
quality.
5.9 Evaluate information on fertilizer use by turf growers
and lawn care companies obtained under TSCA to determine
the relative importance of non-agricultural fertilizer
use as a water pollution source.
Phase II
EPA would implement a second set of water protection
activities if Phase I proved insufficient. For example, additional
measures would be needed if other agencies fail to adopt voluntary
recommendations, if voluntary measure are inadequate, if state
enforcement of regulatory requirements is lacking, or if further
research reveals that the health or ecological risks associated
with nitrate contamination is more severe than current assessments
indicate.
Examples:
o Create state revolving loan fund and grant program to assist
small PWSs with no other recourse in providing alternative
supplies and installing treatment facilities.
[Will require a Federal infusion of start-up money.]
o Use TSCA and SDWA to limit fertilizer applications in targeted
areas.
o Implement a nationwide tax on sources of nitrate and use the
proceeds to help contaminated water suppliers, buy easements
on highly vulnerable land, cost-share manure storage and
composting facilities, cost-share appropriate use of compost,
among others.
o Obtain legislative authority to require farmers to develop
nutrient management plans in watersheds where nutrients impair
or threaten water quality.
o Require farmers to adopt nutrient best management practices in
order to be eligible for farm subsidy payments.
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NITROGEN ACTION PLAN TECHNICAL APPENDIX
INTRODUCTION
Nitrogen (N) is an ubiquitous substance. About 98 percent
of the nitrogen on Earth is tied up in rocks and minerals of the
lithosphere. Atmospheric nitrogen accounts for most of the
remaining nitrogen. It makes up 78% of the Earth's atmosphere, by
volume. Living matter, soils, sea bottoms, and the oceans all
contribute tiny percentages to the total. Nitrogen is an essential
element for life. It is continually being transferred between
soil, water, air, and biota through processes collectively known as
the nitrogen cycle.
Human activities have altered the natural functioning of the
Nitrogen Cycle by adding large quantities of nitrogenous compounds
to local environments. In many places these additions have
overloaded the ability of ecosystems to compensate for these
increases, resulting in significant deterioration of aquatic
habitats. Many estuaries, especially along the East Coast have
become or are becoming eutrophic. Contamination of ground water is
creating concerns about possible human health effects. Once
contaminated, natural removal of nitrate from ground water is
usually an extremely long-term process, and remediation is
generally not practical or possible.
There are several primary reasons for anthropogenic additions
of nitrogen compounds to the environment: to increase agricultural
production (generally commercial fertilizers and animal manure) ; to
supplement lawns, maintain golf courses; to dispose of human
sewage; and as a byproduct of industrial processes, automobile
operation, and animal production.
The Nitrogen Action Plan was developed in response to a
growing national concern about the ecological and health impacts of
nitrogenous compounds. The United States Environmental Protection
Agency (EPA) has developed a national strategy to focus and
coordinate its activities and help states deal with all sources of
nitrogen effectively and efficiently in order to limit risks posed
by contamination from nitrogen compounds, especially nitrate (NO3-
) , nitrite (NO2~) , and ammonia (NH3) , and nitrogen oxides (NOX) .
This background paper is divided into four sections. First,
Risk Characterization looks at the known and theorized risks from,
and exposure to, nitrogenous compounds. The Sources of these
compounds are then analyzed, including the relative importance of
the various sources both nationally and locally. Techniques and
regulation available to limit contamination are evaluated in the
Pollution Prevention section. Finally, the Remediation and
Treatment section looks at technologies and regulation available to
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reduce nitrate contamination in drinking water.
PROBLEM CHARACTERIZATION
Nitrogen compounds have demonstrated adverse environmental,
health, and welfare effects. Ground and surface waters throughout
the United States and in many other countries are contaminated by
nitrogenous compounds. These compounds play a role in all major
air problems. Some health effects have never been demonstrated
conclusively in human populations, but the scientific basis for
concern exists. The Nitrogen Action Plan is, in part, based on the
assumption that because of the uncertainties surrounding the health
effects of nitrate in humans, it is reasonable to limit human
exposure from all sources (NAS, 1981; Forman, 1988).
Ecological Damages
Excessive nutrients in fresh and saline waters have several
wide-ranging adverse effects on species and ecosystems as a whole.
Nitrogen in the form of ammonia is directly toxic to fish and
shellfish. Nitrogen, usually as nitrate, in addition to phosphorus
can cause eutrophication of water bodies. In addition to ecosystem
effects, eutrophication can also limit beneficial uses such as
recreation, tourism, or drinking water. The impact on human
populations is especially great in estuaries since approximately 75
percent of the population of the United States lives within 75
miles of the coast. Nitrogen oxides contribute to degradation of
the atmosphere and water bodies in the form of acid deposition, and
the depletion of the stratospheric ozone layer.
Direct Toxic Effects
Ammonia (NH3) is the nitrogen compound of greatest concern in
relation to direct toxic effects in aquatic environments. It is
discharged into surface water bodies in relatively large quantities
primarily from industrial processes and wastewater treatment
plants. The level of ammonia that is toxic to aquatic life varies
considerably with factors such as temperature, pH, and salinity.
However, ammonia is generally toxic in the range of one to five
mg/L as nitrogen. In the respiratory process, fish excrete ammonia
gas through their gills. When there is a high concentration of
ammonia gas in the water, ammonia will remain in the bloodstream,
killing the fish. There appears to be no human health threat at
levels typically found in water.
Ammonia is one of the leading causes of fish kills according
to the 1988 §305(b) Report. From 1970 to 1978 over reported 200
fish kill incidents were attributed to ammonia, with approximately
10 million fish killed (EPA, Fish Kill File, 1979). These numbers
probably underestimate the extent of the problem since many fish
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kills are not be reported to state conservation agencies. Also,
this estimate omits incidents of reported fish kills where ammonia
could not be specifically determined to be the causal agent.
Ammonia fish-kill data from the 1980s has not been compiled by EPA.
Fish kills from ammonia are usually transitory in nature since
ammonia is generally not stable in water and will convert to
nitrate or volatilize into the atmosphere. However, ammonia may
combine with chlorine in the effluent from wastewater treatment
plants, for example, to form chloramine, a persistent compound that
extends the effects of chlorine (highly toxic to aquatic life)
downstream. Nitrate is not directly toxic in aquatic environments
except at very high concentrations (over 90 mg/L).
Indirect Effects
Excessive loadings of nutrients (phosphorus and nitrogen) pose
significant ecological risks by stimulating the over-enrichment of
estuaries, lakes, reservoirs, bays, and slower streams. This
process is known as eutrophication. Eutrophication occurs when
excess nutrients stimulate the growth of algae and alter the
biological composition of ecological communities.
The availability of nitrogen is generally the nutrient
limiting algal growth in the saline waters of estuaries and bays.
Phosphorus tends to be the limiting factor in lakes, reservoirs,
and slower streams. Although this concept may be too simplistic
for many ecosystems where the limiting nutrient may shift during
the year, generally either nitrogen or phosphorus have dominant
effects on algal growth.
In some cases the ratio of nitrogen to phosphorus (N:P) may be
more important than the absolute amount of either nutrient. Most
algae species favor a water environment containing approximately
ten parts nitrogen to one part phosphorus. When the N:P ratio is
below 10:1, nitrogen tends to be the more important factor limiting
algal growth. However, the optimal N:P ratio for various algae
species ranges from 4:1 to 38:1. (When P is high, N tends to be
limiting in lakes.) Ratios can also shift dramatically during the
course of a year. Therefore, it is necessary to evaluate nutrient
limitations of water bodies during the critical period of the year,
generally the summer, when the water is impaired by algal growth.
There are many studies documenting phosphorus limitation for
fresh waters. However, nitrogen limitation in estuarine waters has
not been rigorously demonstrated (Hecky, 1988). With these caveats
in mind however, several studies show a general trend that nitrogen
tends to be the limiting factor in marine waters (Hecky, 1988),
waters affected by urban activity (Bartsch, 1981; Smith, 1982),
eutrophied fresh waters (Suttle, 1988), and Northwestern waters at
higher elevations (Rhee, Bachmann, Larsen, personal communication,
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* DRAFT (3/5/91) *
1990). Perhaps ten to twenty percent of lakes worldwide are
nitrogen limited (Lee, 1990, personal communication).
Nitrogen enrichment of estuaries has six primary effects,
several of which follow directly from increases in algal growth.
1) Algae attaches directly to submerged aquatic vegetation or
floating algal blooms and blocks sunlight from reaching the
vegetation thereby restricting plant growth. The loss of the
vegetation has been correlated with reductions in waterfowl
populations and elimination of essential habitat for finfish,
shellfish, and other aquatic life.
2) Algal blooms such as red tides, brown tides, and green
tides have been linked to nitrogen enrichment in estuaries. A
toxin is produced in these blooms which can be lethal to fish,
aquatic invertebrates, mammals, and humans (Kann, 1987).
Scientists have seen a world-wide increase in the frequency,
magnitude, and geographic extent of tides (Gutis, 1988). In the
United States, toxic tides have been reported off Long Island,
Rhode Island, North Carolina, Florida, and Washington.
3) Algal blooms die off and introduce ammonia into the water
body thereby creating increased oxygen demands. Water below three
parts per million dissolved oxygen limits the use of habitats by
fish and shellfish. Mobile fish are effectively excluded from the
area of the available habitat with low dissolved oxygen. The
shellfish or slow moving species may die out or have lower survival
rates from the reduction in the available oxygen. Oxygen-depleted
water in Raritan Bay, New Jersey, is responsible for the death of
approximately one million flounder and fluke which were trapped.
4) High nitrogen loadings cause declines in abundance,
biomass, and species diversity, and increase total mortality of the
aquatic community. Opportunistic species, which can take advantage
of the nitrogen, then increase. These species may be a less
desirable food source than the species they are replacing (Boesch
and Rosenberg, 1981).
5) It has been theorized that nitrogen enrichment in
estuaries results in a shift from green algae or diatoms to blue-
green algae. Unlike green algae which can be readily eaten by
minute aquatic herbivores that form the basis of the aquatic food
chain, blue-green algae are often filamentous and covered with
gelatinous sheaths. Therefore, they are undesirable as a direct
food source for aquatic herbivores, and instead accumulate in the
water (Ryther, 1969).
6) Finally, proliferation of algae has been implicated in the
destruction of some coral ecosystems. Algae can overgrow coral
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* DRAFT (3/5/91) *
reefs and kill them. (need citation)
Estuaries
Estuaries and near coastal waters are the most productive
habitats on earth. They serve as spawning grounds, nursery areas,
and feeding grounds for fish and shellfish. Approximately two-
thirds of all fish caught world-wide are hatched in estuaries.
Nitrogenous compounds are major contributors to water quality
degradation in estuaries.
Temporal and Historical Trends Nitrogen inputs to estuaries
vary greatly by the season and rainfall. In years with high
rainfall, substantially more nitrogen is contributed to the surface
water because of increased runoff from the land and the inadequate
ability of sewage treatment plants to handle the increased loads
from the stormwater. Increased rainfall may somewhat dilute the
nitrate concentrations. Resort areas handle larger volumes of
waste during peak vacation periods and therefore discharge more
nitrogen into estuaries.
Historical trends indicate that nitrogen inputs to marine
waters have increased due to urbanization, centralization of sewage
treatment, greater use of fertilizer, and increased deposition from
the atmosphere. For example, the late 1970s and early 1980s showed
a sharp decrease in the diversity of aquatic vegetation in the
Pamlico River Estuary. The North Carolina Division of
Environmental Management attributed the decline to nutrient
loadings, 82 percent of the nitrogen coming from non-point sources
(Harding, 1990) . Data from 1974 to 1981 show the following
percentage increases in total nitrogen loadings: Northeast
Atlantic Coast, 4.0%; Long Island Sound/New York Blight, 3.3%;
Chesapeake Bay, 3.6%; Southeast Atlantic Coast 2.6%;
Albermarle/Pamlico Sound, 3.5%; Gulf Coast, 5.4%; Pacific
Northwest, .8%; California, .7% (Jaworski, ?; Marchetti, 1989;
Smith, 1987).
Currently, the estuarine systems of the Atlantic Coast have
been more affected by nitrogen than those on the West Coast. Low
dissolved oxygen concentrations have been identified in the
following major estuaries (see Figure l): East Coast—Long Island
Sound, East River, Hudson/Raretan Bay, New York Bight/Coastal New
Jersey, Chesapeake Bay, Lower Chowan River, Albemarle Sound, Neuse
River Estuary, Biscayne Bay; Gulf Coast— Tampa Bay, Perdido Bay,
Mobile Bay, Lake Ponchartrain, Central Gulf of Mexico; West Coast—
Puget Sound.
The following estuaries potentially have low dissolved oxygen
concentrations: East Coast—Indian River Bay, Rehoboth Bay,
21
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* DRAFT (3/5/91) *
Cooper/Wando Estuary, Savannah River; Gulf Coast—
Escambia/Pensicola Bay, Galveston Bay, Mississippi Sound; West
Coast—Port Susan, Hood Canal, San Francisco Bay, Los Angeles
Harbor.
Fresh Waters
As discussed above, eutrophication in fresh waters is usually
caused by excessive phosphorus. However, there are examples of
lakes throughout the world that are nitrogen-limited (Dodds, 1989) .
For example, Florida has several nitrogen limited lakes because
there is an abundant supply of naturally occurring phosphorus.
Algal growth in Lake Tahoe is limited by nitrogen (Jones and Lee,
1990). There are also many other lakes that are limited by both
phosphorus and nitrogen depending on many different factors.
In general, nitrate levels in the Great Lakes have been
increasing. Lake Huron, for example, has an annual increase of
.011 mg/L nitrate per year and Lake Ontario's annual increase is
.009 mg/L per year. Lake Superior is the only Lake that shows a
decrease at .001 mg/L per year (Great Lakes Water Quality Board,
1989). Even though no adverse impacts from these increasing
nitrate levels have been noted in the Great Lakes to date, the
Great Lakes Water Quality Board (1989) believes that the increases
could have a significant impact on ecosystems within the Lakes.
Since excess nitrogen has the potential to change phytoplankton
(algal) communities, as noted above, the food chain may be
disrupted.
US EPA Water Quality standards
Through the Clean Water Act, water quality standards [§ 303]
are established to protect the public health and welfare, enhance
water quality to provide for the protection and propagation of
fish, shellfish, and wildlife, and for recreation in and on the
water. These standards are developed for the full range of surface
water bodies. EPA makes recommendations to the states in the form
of criteria for development of state water quality standards. Then
US EPA approves the state-adopted standards for interstate waters,
evaluates adherence to the standards and oversees enforcement.
EPA criteria for ammonia is based on a formula taking the
fluctuations of flow, temperature, and pH into account. 27 states
and territories have adopted numeric standards for ammonia. Other
states have been reluctant to adopt numeric standards because of
the cost of complying with the standards and EPA's perceived lack
of confidence in the ammonia freshwater criteria.
The current water quality criteria for nitrate is based solely
on the health endpoint for drinking water supplies, 10 mg/L (US
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* DRAFT (3/5/91) *
EPA, 1976). A national standard for nitrate based on water quality
impacts is considered inappropriate because the nitrate level which
adversely affects various water bodies depends, to a great extent,
on site-specific conditions: temperature, turbidity, plant growth,
presence or absence of nitrogen-fixing bacteria, and other physical
or chemical characteristics. However, EPA's Office of Water
Regulations and Standards has listed the development of nutrient
criteria (nitrogen and phosphorus) as a Level I Priority. US EPA
anticipates that three years will be required to develop the
nutrient criteria guidance, but current funding levels will delay
publication until 1996.
States rarely specify water quality standards for nitrate
apart from the health effects level. Some states qualitatively
describe their nutrient standards, which include nitrate. For
example, Arkansas standards state that for nutrients "materials
stimulating algal growth shall not be present in concentrations
sufficient to cause objectionable algal densities or other nuisance
aquatic vegetation" (US EPA, 1988) . Some states do list nitrate
water quality standards: Hawaii, 0.008 mg/L in estuaries, 0.07
mg/L in streams; North Dakota, 0.375 mg/L in lakes; New Jersey, 2
mg/L, Nevada, .4-5 mg/L (depending on the specific water body).
Air Quality
Nitrogenous compounds in the air contribute to adverse effects
in both the atmosphere and on terrestrial ecosystems and materials.
Emissions are expected to increase in the long term. Nitrogen
oxide gases (NOX) contribute to all major air problems although
they are not the primary constituent of any of them: chemical
formation of acid rain, stratospheric ozone depletion, climate
change, creation of ozone in the lower atmosphere, health effects,
and visibility degradation. Aerial deposition of nitrogen oxides
on estuaries may be an important pathway for nitrogen loadings
(Jaworski, 1990). Increased soil nitrogen from fertilizers and
acid rain may have an effect on global warming. Atmospheric
deposition has also been observed to lead to high levels of nitrate
in ground water. In the San Gabriel Mountains near Los Angeles,
California, ground-water concentrations from nearby, relatively
unpolluted watershed were typically one to three orders of
magnitude lower.
Acid Deposition
Acid deposition is composed of both wet and dry deposition.
Acid rain is the name most commonly used for wet deposition, but
nitrogen can be also be added to ecosystems from fog and dry
deposition. NOX is a precursor to nitric acid which is one of the
primary components of acid deposition along with sulfuric acid and
minor contributions from hydrochloric acid. Deposition is
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considered acidic if the pH is 5.0 or below. Nitrogen is often a
major contributor to acidity in episodes of pH depression in
sensitive surface waters. These episodes can be lethal to
individual fish and invertebrates.2
Acid rain has been implicated in several ecological effects.
Forests in central and eastern Europe, Norway, Sweden, the United
States (especially northeastern states), and Canada are dying.
Needles of coniferous trees are turning yellow and falling off.
Airborne pollutants including N0x are thought to play a significant
role. Acid deposition also contributes to the erosion of stone in
buildings and statues and the corrosion of metals. Acid in lakes,
especially in areas with few natural buffers, can suffer depletions
of aquatic life. For example, 30 percent of Adirondack lakes, 12
percent mid-Atlantic/Coastal plain lakes, and 23 percent of Florida
lakes are acidified (Air/Water Pollution Report, 9/10/90). 10
percent of the fish populations in these lakes have been lost. Few
fish species can sustain viable populations in water below 5.0 pH.
Stratospheric Ozone Depletion
Theoretically, any increase in the amount of nitrous oxide
(N20) reaching the stratosphere is likely to lead to some depletion
of the ozone layer (NAS, 1978). Nitrous oxide is formed from the
process of denitrification, conversion of nitrate to nitrogenous
gases. As more nitrate is added by the manufacture of fertilizers
or the cultivation of legumes which fix nitrogen from the
atmosphere, more nitrate is available for denitrification. The
depletion of the stratospheric ozone layer leads to increased
ultraviolet radiation on earth which can cause increased rates of
skin cancer and birth defects. Nitrous oxide appears to have about
one-tenth the effect of chloroflourcarbons (CFCs) on the ozone
layer.
Climate Change
Methane gas has been increasing in the atmosphere by about
1.1% a year since 1980. Steudler, et al. (1989) found that
increased nitrogen content in soils seems to interfere with the
2There are important uncertainties associated with this
statement. The quantitative relationship between nitrogen
transport from watersheds and nitrogen deposition is an area
requiring more research. Further, there is some question about
whether such mortality to individuals could be compensated for by
populations in nature. If such compensation does occur,
populations of organisms within a region might not be negatively
impacted.
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ability of microorganisms to take up methane from the air. The
bacteria prefer nitrogen to methane as an energy source. In a
fertilized temperate forest, this ability was reduced by one-third.
It is not known what effect this phenomenon might have on global
methane levels or if increases in methane production rather than
decreases in methane uptake may be responsible for the rising
methane levels in the atmosphere. If the level of methane is
rising it could be contributing to the "greenhouse" effect.
Ozone
In the lower atmosphere, complex photochemical reactions that
involve NOX, carbon monoxide, and volatile organic compounds
produce ozone. The rate of ozone production depends on the ratio
of NOX to volatile organic compounds in addition to their absolute
levels. Ozone contributes to reductions in the yield of various
agricultural crops: corn, 1%; cotton, soybeans, 7%; alfalfa, 30%
(NAPAP, 1987). Two forests in California in the San Bernadino
Mountains and the southern Sierra Nevada have been shown to have
experienced declines caused by increased ozone levels.
Human Health Risks
This section evaluates the risk to human health from nitrate
in drinking water on an individual and a national basis. Acute
toxicity results from the conversion of nitrate to nitrite in the
body. Infants under six months appear to be the population most
sensitive to effects of nitrate ingestion. EPA has not yet
evaluated nitrate and its theorized role in the development of
cancer. Studies are not conclusive. Exposure to nitrate varies
significantly across the population based on diet and drinking
water source. Some estimates on national exposure have been
calculated.
Methemoglobinemia
Depending upon a number of factors, nitrate (KO3~) is
generally the stable form of nitrogen in water. It is relatively
non-toxic to humans. However, nitrate can be reduced by bacteria
in water, in saliva, or in the stomach to form nitrite (NO2-). In
healthy adults, about five percent of ingested nitrate is reduced
to nitrite. However, a large variation exists between individuals
(Packer et al., 1989). Up to 50 percent may be reduced in people
with low stomach acidity and a bacterial infection (NAS, 1981).
Infants reduce more nitrate to nitrite than adults because of their
naturally lower gastric acidity (Fan, 1987). Nitrite is the
specific chemical of concern because it can bind with hemoglobin in
the blood to form methemoglobin (metHb). MetHb prevents oxygen
from binding to red blood cells and results in the inability of the
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* DRAFT (3/5/91) *
blood to transport oxygen.
The average adult has a metHb level in the blood of one
percent or less. Less than two percent metHb is average for a
child. Clinical symptoms of the disease methemoglobinemia, or
"blue baby syndrome" as it is commonly called, appear when the
level reaches 10 percent. The skin takes on a bluish cast and
breathing may become difficult. Headaches, weakness, and
breathlessness occur at 30 to 40 percent. Coma and death can result
when levels of metHb in the blood are 60 percent or greater.
Methemoglobinemia is easily treatable when it is diagnosed in time
(Coroly, 1945).
Infants under six months of age are most at risk of developing
methemoglobinemia from the ingestion of nitrate from levels of 10
milligrams per liter (mg/L) nitrate-nitrogen (N03-N)3 or greater in
drinking water. There are several factors which seem to contribute
to this occurrence: high fluid intake in proportion to body
weight, high percentage of fetal hemoglobin in the blood, temporary
deficiency of metHb reductase, and lower gastric acidity (NAS,
1981). In addition, infants with diarrhea or respiratory illnesses
may be predisposed to developing methemoglobinemia (Shearer, 1972) .
Shearer studied metHb levels of 256 infants. One-third of the
infants with respiratory disease had elevated metHb levels, but the
highest levels were found in infants with diarrhea. The level of
bacteriological contamination in the water source also seems to be
an important factor. Older children and most adults show an
effect, if any, only at much higher levels of nitrate
contamination. Craun (1981) tested 102 children ages one to eight
years old who drank water with 22 to 111 mg/L nitrate and did not
find any statistically or biologically significant increases in the
metHb level in their blood based on the nitrate level in the
drinking water.
Though the actual incidence of methemoglobinemia in the United
States is unknown since national statistics are not maintained, it
appears to be rare. Walton (1951) reported over 278 cases between
1939 and 1950 with 39 deaths. 2,000 cases were documented in North
America and Europe between 1945 and 1971 (Shuval and Greuner,
1971). Fatalities were reported in seven to eight percent of the
cases. The most recent death occurred in South Dakota. A two
month old infant who received supplementary feedings of powdered
'studies present contaminant levels in two ways, as nitrate-
nitrogen (NO3-N) or as nitrate (NO,) . All measurements in this
report are presented as nitrate-nitrogen, the form used by EPA.
The word nitrate will be used for convenience. When NO3 was used
in the original study, appropriate conversions have been made. 10
mg/L NO3-N equals 44.3 mg/L N03-
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formula mixed with well water with a nitrate concentration of 150
mg/L died in 1986 (Johnson, et al., 1987).
Reproductive and Developmental Effects
Several recent epidemiological studies have raised a concern
that there is a relationship between congenital malformations and
the nitrate level in the drinking water consumed during pregnancy.
In a study in South Australia, Dorsch (1984) found a statistically
significant three-fold increase in risk of malformations of the
central nervous system (CNS) and the musculoskeletal system of the
fetus for women whose drinking water contained 1.1 to 3.4 mg/L
NO3-N. There was a four-fold risk when the nitrate level was above
3.4 mg/L. Arbuckle et al.(1986) conducted a similar study in New
Brunswick, Canada. He found no significant differences, but risk
of CNS defects increased with increasing nitrate levels (up to 5.6
mg/L NO3-N) in well water. The same increase was not observed in
spring water or public water supplies.
Neither study is considered sufficient to discern a
relationship between nitrate and congenital malformations since the
levels of exposure were only estimated. There may be other factors
in the water source or elsewhere that explain the malformations
found in the studies. These studies do, however, suggest a focus
for more research.
Effects of Chronic Exposure
Chronic effects of subclinical levels of acquired
methemoglobinemia from nitrate intake on human growth, development,
and general health have not been studied. Concern exists because
of the decreased oxygen carrying capacity of the blood resulting
from increases in methemoglobin. Studies of people with hereditary
methemoglobinemia may provide a model. Adults with chronic
methemoglobin concentrations in the blood of 10 to 25 percent seem
to have no adverse health effects other than a bluish skin color.
Pregnancy is usually uncomplicated and life
expectancy is not decreased (Jaffe, 1981).
Carcinogenic Effects
Nitrates and nitrites themselves have not yet been classified
as to human carcinogenicity, but EPA is currently evaluating the
classification. Nitrate alone does not appear to be a carcinogen,
but when nitrate is reduced to nitrite in the body or when nitrite
is ingested directly, it can combine with nitrosatable substrates
(secondary amines, amides, carbamates) in the body to form
N-nitroso compounds, such as nitrosamines. N-nitroso compounds are
classified as probable human carcinogens. Inhalation of nitrogen
oxides have also been implicated in the formation of N-nitroso
28
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* DRAFT (3/5/91) *
compounds in the body (US EPA, 1982, Air Quality Criteria).
Several substances, such as vitamins C and E and several
phenols, can inhibit the formation of N-nitroso compounds in the
body. Vitamin C acts by reducing nitrate to nitrogen or nitric
acid (Mirvish, 1983). Therefore the absolute amount of nitrate in
vegetables and other sources is not as important as the ratio
between ingested nitrate or nitrite and the inhibitors (Forman,
1988) . The amount of vitamin C or E needed to block the
nitrosamine compound formation is not known.
Many studies have investigated the relationship between
nitrate intake and cancer. The epidemiological evidence implicates
nitrate in stomach and esophageal cancer, but the studies are
generally flawed because of the lack of specific information on the
history of exposure to nitrate, nitrite, and N-nitroso compounds
for the individuals who developed cancer. Confounding factors such
as the role of salts in the diet and socio-economic status are
often not controlled for as well. Although no definite association
has been proven, the studies do tend to lend support to the idea
that nitrate and nitrite ingestion is higher in countries where
gastric cancer is more prevalent (NAS, 1981). Several studies
conducted in Great Britain, however, showed no association between
nitrate intake and cancer (Al Dabbagh, et al., 1986, Forman, et
al., 1985). The National Cancer Institute is currently conducting
an epidemiological study on farmers in Nebraska to investigate the
carcinogenic potential of nitrate.
Pathways of Exposure
Individual Exposure
Nitrate
Humans are exposed to nitrate from a variety of sources: foods
(including water, fruits, juices, cured meats, baked goods, fresh
meats, milk products), water, and air. Figure 2a presents
estimates of the average per capita exposure to nitrates in the
United States. For the average person, vegetables are the only
significant source of exposure. For non-vegetarians however, if
nitrate in drinking water equals the drinking water standard, water
becomes the major (54%) source of exposure.
Since infants under three months generally exclusively ingest
liquids, virtually the only source of exposure to nitrate in this
subpopulation is drinking water. Water can be added to
concentrated or powdered formula or it can supplement feedings from
breast milk or prepared formula. Breast milk does not appear to be
a source of nitrate for infants (Shuval and Gruener, 1977).
29
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Nitrosatable substrates are present in many types of foods;
fish, poultry, meat, dairy, and grain. They are also present in
some agricultural pesticides like aldicarb, carbofuran, carbaryl;
more than 30 drugs; and many cosmetics.
Among vegetables, beets, lettuce, spinach, celery, radishes,
and turnip greens are especially high in nitrate. Carrots readily
accumulate nitrate. Many factors affect the level of nitrate in
vegetables. The three most important variables seem to be the
genotype, amount of nitrogen fertilizer applied, and light. Higher
rates of nitrogen fertilizer application can also decrease the
vitamin C content of vegetables (Hornick, 1988).
Researchers have also suggested that nitrate may be produced
in mammals since some studies show that humans excrete more nitrate
than they ingest (NAS, 1981). Packer (1989) demonstrated that
subjects excrete between 4 and 5 milligrams of nitrate per day or
about 20 percent of average nitrate intake in the United States.
Nitrite
Nitrite (generally as sodium nitrite) is added to cured meat
products to control pathogens, inhibit spoilage, and contribute to
their flavor and color. FDA limits the amount of nitrite added to
all cured meats and prohibits the addition of nitrate. Since 1978
vitamin C, in the form of sodium ascorbate, has been added to bacon
to inhibit nitrosamine formation. Nitrite is also found naturally
in some foods. Figure 2b presents estimates of the average per
capita nitrite exposure in the United States. The great majority
of average nitrite exposure comes from reduction of ingested
nitrate to nitrite. However, for individuals whose drinking water
contains 1 mg/L nitrite (the drinking water standard), the water
would represent the major source of nitrite exposure.
Drinking Water Exposure
Public Water Systems
Through the Safe Drinking Water Act (SDWA), EPA has regulatory
authority over water systems that have at least 15 connections or
serve 25 or more individuals year round. These are defined as
public water systems since they serve the public, but they can be
publicly or privately owned. Under SDWA regulations, EPA sets
unenforceable maximum contaminant level goals (MCLG) for drinking
water contaminants at "the level at which no known or anticipated
adverse effects on the health of person occur and which allows an
adequate margin of safety" [SDWA § 1412 (b)(4)]. US EPA then sets
an enforceable Maximum Contaminant Level (MCL) as close to the MCLG
as feasible, taking cost into account [SDWA § 1412 (b)(5)]. Public
31
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* DRAFT (3/5/91) *
water systems must ensure that the water they supply does not
violate the MCLs.
EPA has set the MCLG for nitrate at 10 mg/L to protect the
public from the acute effects of methemoglobinemia. The MCL is set
at the same level since water treatment can remove nitrate and
nitrite to levels below the MCLG. The MCLG is based on a public
health survey that showed no clinical cases of methemoglobinemia
(no observable adverse effect level or NOAEL) when the nitrate
level in drinking water was at 10 mg/L or below (Walton, 1951) .
Although 80 percent of the cases occurred when the water was
contaminated with over 50 mg/L nitrate, 2.3 percent of the cases
were associated with nitrate levels just above the MCL (11-20
mg/L).
The World Health Organization and the European Community (EC)
have set a standard for nitrate similar to the MCL. However, the
EC standard for nitrite is set at one-tenth the MCL. The EC has
set a recommended level or guide level at half the standard. Two
West German surveys found that about four percent of the
methemoglobinemia cases occurred when the drinking water was below
10 mg/L (Simon, 1964). However, the bacteriological contamination
of the water source and nitrate intake from food was a known factor
in two of those cases. There is no uncertainty factor below the
NOAEL.
An MCLG and MCL has been set for nitrite at 1 mg/L using an
uncertainty factor of ten from the nitrate level, since nitrite is
the toxic agent of concern. Nitrite rarely occurs naturally in
water. When it is found, it is usually because the water is
already highly contaminated by bacteria. A combined nitrate/nitrite
level has also been set at 10 mg/L.
All public water systems (PWSs) must report violations of the
MCLs to the state or EPA. These violations are compiled in the
Federal Reporting Data System (FRDS). According to FRDS, from
October 1987 to April 1990, 280 community water systems were out of
compliance with the nitrate MCL. (See Figure 3.) Based on this
data, about 1.1 million people were exposed to excess levels of
nitrate in public water systems. 92 percent of these systems serve
very small populations (under 3,300) and rely on ground water for
their supply. However, over half of the total population exposed
to nitrate contamination in public systems use surface water
supplies. The majority of the violations are between 11 and 20
mg/L. Ten systems had levels of more than 25 mg/L. The highest
concentration recorded was 380 mg/L.
The FRDS data probably represent a minimum number of people
served by public water systems exposed to nitrate levels above the
MCL. GAO (1990) , in an investigation of SDWA implementation, found
33
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* DRAFT (3/5/91) *
Zthat the number of violations is considerably understated due to
sampling error by water system operators, some intentional
falsification of data, and identified violations not reported to
EPA. US EPA Regions 2 (NY, NJ, Puerto Rico) and (UT, CO, WY, ND,
SD, MT) reported no violations of the nitrate MCL. A 1985 survey
of states by the American Well Water Association reported a total
of 38 violations in states served by Region 8. USDA estimates that
31 million people rely on ground water PWSs in regions with
potential for contamination (Nielsen and Lee, 1987). In a report
prepared for US EPA's Office of Drinking Water (Wade, Miller Assc.,
1990), a model developed based on previous water supply surveys,
estimated the actual number of people exposed to nitrate above the
MCL through public water supplies at 1.7 million.
In order to develop a statistically reliable national
assessment of the frequency and concentration of agricultural
chemicals in wells, EPA sponsored the National Survey of Pesticides
in Drinking Water Wells (US EPA, 1990). The survey tested 1350
statistically selected wells (700 private, 650 public) for 127
analytes, including pesticide degradates, nitrate, and nitrite.
As expected, since nitrate can occur naturally in ground
water, nitrate was by far the contaminant most commonly found in
the Survey. 52.1 percent of community water system wells were
estimated to contain detectable levels of nitrate (over .15 mg/L).
1.2 percent or 1,130 systems nationally were estimated to contain
nitrate levels above the MCL. No information was available on
wells containing between 3 mg/L (background level) and 10 mg/L
(MCL), or the actual population exposed. The maximum concentration
found was 13 mg/L.
Domestic Water Supplies
It is difficult to estimate the number of people exposed to
nitrate contamination through the 10.5 million private wells.
There are no federal or state programs which regulate most domestic
wells or require regular testing. The National Survey of
Pesticides in Drinking Water Wells (USEPA, 1990) provided the first
national estimate of nitrate levels in private wells. The Survey
estimated that 57 percent of the private wells in the United States
contain nitrate. 2.4 percent or 254,000 wells were estimated to
contain levels above the MCL. Again, population numbers were not
estimated. It is not yet possible to compare the nitrate levels in
the 11.7 percent of private wells located on farms to non-farm
private wells from the survey results.
Holden and Graham (1990) provide another large-scale
statistical survey of rural wells in areas where the pesticide,
alachlor is used (principally the Mid-West). Approximately five
percent of shallow rural wells have nitrate levels that exceed the
35
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* DRAFT (3/5/91) *
MCL. The percentage doubled for wells on farms. Another 19
percent have levels that are less than 10 mg/L, but greater than 3
mg/L, probably showing anthropogenic influence. The results of
both surveys are a one time picture of contamination. USDA
estimates that 19 million people who rely on private wells are in
areas with potential for ground water contamination. (Nielson and
Lee, 1987)
A survey of readily available local, state, and regional
nitrate data (Hallberg, 1989) confirmed the results of the
statistically based survey of Holden and Graham. The monitoring
reports from these other areas are generally not statistically
based and are often biased toward agricultural areas. They are
often designed to investigate vulnerable or known areas of
contamination. Several states have done more thorough
investigations. Statewide, Iowa estimates 18 percent of the rural
domestic wells violated the MCL; Nebraska, 17.5%; Kansas, 28% (farm
wells); and California, 10%. Probably a minimum of two million
people are exposed to nitrates over the MCL through domestic water
supplies.
Ground Water
It is difficult to predict the number of people who may be
exposed to high nitrate levels in the future. Most studies sample
drinking water wells rather than monitoring wells in fields or from
deep aquifers. Therefore no real assessment of ground water in
general is available from which to make predictions. However,
because of the chemical stability of nitrate, soil storage, slow
infiltration rates, and complex ground water flow paths that have
the capacity to retard a plume of nitrate, it is likely that future
levels of nitrate in ground water will continue to rise regardless
of proactive measures taken to limit nitrate contribution from
various sources (Keeney, 1986). Depending on the soil type and
other factors, nitrate can take decades to reach ground water.
The United States Geological Survey (USGS) has collected over
87,000 nitrate samples in a data base known as WATSTORE (National
Water-Date Storage and Retrieval System). These data have been
collected from myriad special projects and public water system
analyses over the past 25 years. While these numbers do not
represent a national sample historically or regionally because of
the variety of methods and reasons for collection, they do show
that many areas of the country have nitrate levels elevated by
human activities (Madison and Brunett, 1985). Ground water
sampling generally show higher nitrate concentrations from shallow
wells. The levels tend to decrease with increasing depth. Figure
4 shows the map Madison and Brunett produce based on WATSTORE.
36
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Ground and Surface Water Interconnection
Nitrate contamination of ground water is not only a drinking
water concern. An intimate association exists between ground and
surface waters, such that ecological concerns exist as well. The
interconnection between ground and surface waters also complicates
nitrate concentration analysis. Much of the stream flow in humid
regions (75-90%) may be ground-water discharge, rather than
collected surface run-off. Ground water has been found to
contribute more than 85 percent of the nitrogen load to Buzzards
Bay, Massachusetts (EPA and MA Executive Office of Environmental
Affairs, 1990). In arid glacial or karst regions, surface water
may recharge ground water. Consequently, nitrate contamination can
be recycled through the entire hydrologic system. Contaminated
ground water may contaminate and be diluted by surface water or
vice versa. Thus, ground-surface water interaction can be both
beneficial and harmful. The slow movement of ground water can make
it a reservoir for nitrates that can continue to contaminate
surface water for years after other sources of nutrients have been
controlled.
Economic Risks to Agriculture
Animal Production
Ruminant animals, such as cows and sheep, along with infant
pigs and chickens are susceptible to nitrate/nitrite toxicity
(Keeney, 1986; Hansen et al. , 1987; Shirley, 1975; Young and Mancl,
n.d.). Generally concentrations of nitrate in drinking water less
than 100 mg/L are safe for cattle. The symptoms for acute
nitrate/nitrite toxicity include: asphyxiation and labored
breathing, rapid pulse, frothing at the mouth, convulsions, blue
muzzle and blue eye tint, and chocolate brown colored blood. (SCS
lit search). in pregnant cows, the oxygen supply to the fetus will
be adversely affected after nitrate intake, especially by the lower
oxygen transfer through the placenta. When the oxygen transfer to
the fetal blood decreases too sharply, intra-uterine death and
ultimately abortion may result. Nitrate toxicity has been
associated with symptoms of poor growth, fertility problems,
abortions, and general poor health (SCS, 1989).
Livestock may also develop symptoms of nitrate toxicity by
eating fodder containing high nitrate levels. Feed may be toxic
especially when harvested after a drought.
Welfare Effects
High nitrate levels in ground and surface water can lead to
adverse effects in areas other than human health or ecosystems.
Nitrate contamination can cost individuals and communities
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* DRAFT (3/5/91) *
significant amounts of money because of the costs of such factors
as well relocation or deepening, drinking water treatment,
development of alternative water supplies, denial of loans for
houses or businesses, reduced tax base, and the need for the
development of land use restrictions (Anton, 1988). Nitrate levels
above the MCL were the major cause of the closure of public wells
identified in a 1985 survey conducted by the American Well Water
Association. In California, nitrate contamination has caused the
abandonment of more drinking water wells than any other chemical.
In 1986 alone, the California Department of Health received
requests from public water systems for $48.7 million dollars (far
in excess of available funds) for the remediation of nitrate
contamination. The Department assumed that many other systems were
in need of funds, but did not bother to apply (Anton, 1988).
It is impossible to estimate how many private drinking water
wells might have been abandoned throughout the country as a result
of high nitrate levels. One investigation of the Columbia aquifer
on the Delmarva Peninsula in Maryland stated simply that many wells
in the shallowest and most productive part of the aquifer had been
abandoned because of the nitrate levels (USGS, 1984) . The aquifer
is the most heavily used water source in the area.
Increases in algal growth and blooms can create conditions
highly unfavorable to recreation in surface waters, thereby
decreasing tourism.
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* DRAFT (3/5/91) *
SOURCES OF NITROGENOUS COMPOUNDS
A wide range of sources of nitrogenous compounds circulate in
the environment as a result of both natural processes and human
activity. It is difficult to evaluate the relative importance of
the diverse sources of nitrogenous compounds in regard to threats
to human health or the health of ecosystems because it varies
greatly from place to place according to many complex biological,
chemical, and physical processes or attributes. Local land use is
also a key factor in this evaluation.
On a national scale, mineralization of organic nitrogen in the
soil represents the largest natural source of nitrate to the soil
system. Commercial fertilizer is the largest anthropogenic source
(White, 1989) . However, sources that rank high in terms of the
magnitude of their contribution on a national scale, may cause no
adverse impacts in many areas of the country. Conversely, sources
that are considered relatively minor nationally, such as septic
systems or feedlots, can cause severe local impacts. In order to
implement effective policies that reduce nitrogen loadings, it is
necessary to evaluate all sources that may be causing area specific
air or water quality problems.
This section will describe the sources of contamination by
nitrogenous compounds in the environment, concentrating on sources
that are most subject to policy manipulation.
Nitrogen Cycle
In order to assess the relative impacts of human activity on
surface and ground water it is necessary to first examine the
natural processes by which nitrogen is converted into its various
molecular forms and transported through and between different
media. This dynamic, complex process is referred to as the
nitrogen cycle. Figure 5 shows a simplified version of the
nitrogen cycle. It identifies the physical processes involved in
the creation and destruction of the many forms of nitrogen.
Nitrogenous compounds are transformed as they continually
cycle between soil, water, air, plants, and animals. Anthropogenic
activity can add nitrogen to each component of the cycle, however,
these compounds will be formed to some extent irrespective of human
intervention.
Nitrogen is naturally found in soils in three major forms:
organic nitrogen, ammonium nitrogen, and soluble inorganic ammonium
and nitrate compounds. Organic and ammonium nitrogen, which
represent about 98 percent of all soil nitrogen, are bound to the
surfaces of soil minerals and organic matter. They can be carried
40
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Figure^ s
The Nitrogen Cycle
(Ml.... fr.m I I NOT NO.' I
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Not*: Deoths oi soil and atmospheric zones are not rendered to scale Source:
41
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* DRAFT (3/5/91) *
to surface water by erosion of the soil. Nitrate is soluble and
not absorbed by the soil, therefore, it is available for transport
to ground and surface water whenever water moves.
One to five percent of the organic nitrogen annually converts
to soluble forms (White, 1989). This process is known as
mineralization. During mineralization organic nitrogen is
converted to ammonium, ammonium to nitrite, and nitrite finally to
nitrate (the soluble stable form of nitrogen). Mineralization
rates can vary significantly from region to region depending on
climate and carbon content of the soil.
Once the plant root zone becomes saturated (as may occur
during storm events or through irrigation), some water will be
pulled, by gravity, into the unsaturated zone where water and air
share the space between soil particles. Water then moves into the
saturated zone or ground water table where all space between the
particles is filled with water. Geology and topology aside, the
rate at which nitrate moves through the soil depends on the rate of
ground-water recharge, which is a function of rainfall, irrigation
rates, and the permeability of the soil.
Nitrogen is added to soils by human activity and natural
processes which include: commercial fertilizers, green and animal
manures, sewage, crop residues, nitrogen fixation by legume
bacteria, fixation by other types of plants and organisms, and
atmospheric deposition (wet or dry). Soils lose nitrogen via:
plant uptake, denitrification (transformation of nitrate to
nitrogen gases), drainage, and erosion (Buckman and Brady, 1969).
This entire process is dynamic. Nitrate levels will generally vary
by temperature, organic content of the soil, season, and year.
Monitoring to determine nitrate content in various media will
necessarily artificially freeze the cycle and provide only a "snap-
shot" of nitrate levels at that particular point in time.
Nitrate Mass Balance
To more accurately assess the amount of nitrate available to
potentially contaminate ground or surface water in a specific area,
mathematical models are used to predict a mass balance. A mass
balance requires that the nitrate mass be inventoried to account
for the amount of nitrate that is applied on or near the surface,
added through aerial deposition, created or destroyed in
environmental media, and stored in soils and aquifers.
The predictive capability of mass-balance models is hampered
by three main factors. First, we do not have adequate monitoring
data to determine the current concentration of nitrate in ground
water. The statistically based monitoring data on domestic
drinking water wells comes predominantly from shallow, rural wells.
42
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* DRAFT (3/5/91) *
These data can not be used to give an accurate picture of ground
water contamination in general. Second, the rates of creation and
destruction of nitrate is not fully understood. Denitrification
may be very important to predicting the amount of nitrate that is
likely to remain in an aquifer or estuary, but little is known
about the quantitative relationships in this process in ground or
surface waters (Hallberg, 1989; US EPA, 1990). Finally, estimates
are needed for the amount of nitrate stored in of different soils
and the rate of nitrate movement from soil storage to ground water.
Several studies estimate that 30 to 60 percent of nitrate applied
to the soil in the form of fertilizers remains in the soil from
year to year depending on crop uptake and percolation rates (White,
1989; Bundy and Maione, 1988).
Natural Background Levels
A mass balance model must take into account background levels
in ground water as a result of natural processes. Nitrate
concentrations less than three parts per million (ppm) are commonly
accepted as being representative of natural conditions in ground
water (Madison and Brunett, 1985). However, the range of natural
levels can vary widely, especially for ground water basins in the
western United States with internal drainage. An area in Nevada,
for example, has ground water with naturally occurring nitrate
concentrations in excess of 300 mg/L. Parts of some estuaries are
naturally eutrophic. A mass balance would be necessary to identify
where this condition was not influenced by human inputs.
It is generally the case that widespread contamination of
ground water at levels above the MCL is the result of anthropogenic
influences upon the environment. However, natural soil nitrate was
identified as a major source of nitrate in the ground waters of
Runnels County, Texas (Kreitler and Jones, 1975).
Use of Isotopes to Identify sources
Several researchers have attempted to use the ratio between
the two stable isotopes of nitrogen to determine the origin of the
nitrate found in ground water. The ratio of UN to 15N indicates
whether organic sources such as animal wastes or vegetable matter
are present. Manufactured fertilizers produce an isotope mix
similar to that found in the atmosphere. Organic sources alter the
mix of the two isotopes.
After reviewing the studies using this technique, Keeney
(1986) concluded that the isotope ratio test can only be used
reliably in relatively simple systems where there are only one or
two sources and little denitrification occurs. Its usefulness is
limited to areas where the outcome is already fairly obvious based
on land use and agricultural systems, or where sources could be
43
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* DRAFT (3/5/91) *
determined a lot more cheaply by talking to extension agronomists
or fertilizer dealers.
AGRICULTURAL SOURCES
Nitrogen is a vital component in the growth of plants.
Farmers, therefore, seek to augment available nitrogen in the soil
to increase crop yields. When the prairies were plowed under,
large quantities of nitrogen were released which provided nutrients
for the crops. Commercial fertilizers primarily, but also animal
manure, green manures, sludge from waste water treatment
facilities, and food processing wastes are all added to croplands
to increase yields. Legumes, such as alfalfa or clover, are grown
for forage and to add nitrogen to the soil because of their ability
to convert atmospheric nitrogen into ammonia. Animal production
including the increase in concentrated feedlots, poultry
operations, and dairy farms are all important sources in local
areas.
Although many sources of agricultural nitrogen nationally are
quantified in this section, it does not mean that all this nitrogen
is available to contaminate ground and surface water. It does
however indicate which sources could cause problems. Much of the
applied nitrogen is taken up by plants, volatilized, immobilized in
the soil, or denitrified. Sources of excess nitrogen in a specific
area must be defined by mass balance.
Commercial Fertilizer
Commercial fertilizer, without other sources of nitrogen and
even when applied parsimoniously, can contribute to ground water
contamination in particularly vulnerable geographic settings (i.e.,
combinations of course textured soils, with fractured karst, above
surficial aquifers, with high recharge rates). In other settings
where fertilizer is the only source of nitrogen, nitrate
contamination tends to be associated with application rates in
excess of agronomically optimum rates. This occurs for the
following reasons: research has not identified the optimum
application rate, farmers do not give adequate credits for other
sources of nitrogen, or they simply do not follow the best
available recommendations (Hallberg, 1987; Keeney, 1986; University
of Nebraska, 1990) . A survey of nitrogen use in the Big Spring
Basin in Iowa, indicated that farmers were not correcting
fertilizer application rates for alfalfa and animal manure. On
average they were using 80 Ibs per acre more than was needed
(Keeney, 1986). Fall application of fertilizer (or animal manure)
to bare soil (not accompanying a fall crop), although increasingly
less common, still occurs and is a particular problem for adjacent
surface waters.
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* DRAFT (3/5/91) *
Fertilizer use has been implicated in the contamination of
ground and surface waters in many different studies. Continual
nitrate increases in Iowa surface and ground waters since 1950 is
attributed primarily to nitrogen fertilizers (McDonald and
Splinter, 1982). High nitrate contamination of ground water on
Long Island are attributed to septage and over-use of fertilizer on
potatoes (Keeney, 1986, p.278). Studies of various Illinois
watersheds cite fertilizer use as the major source of nitrate
contamination (Keeney, 1986). Cantor (1987) surveyed literature on
nitrate contamination from fertilizer application and reported on
studies from 14 states that identified fertilizer as the source of
nitrate in ground water study area (New York, California, Nebraska,
Ohio, Connecticut, Minnesota, North Carolina, Iowa, Texas,
Delaware, Arizona, Missouri, Washington, and Wisconsin).
National Usage
The nitrogen in commercial fertilizer (fertilizer nitrogen)
generally takes the form of ammonia, ammonium salts of sulfate,
nitrate, or urea (an organic compound) . The most widely used
formulations of nitrogen fertilizer are nitrogen solutions,
anhydrous ammonia, urea, and ammonium nitrate with 8.3, 5.4, 2.7
and 2.2 million tons, respectively, sold annually (Vroomen, 1987).
The nitrogen content of these fertilizers ranges by weight from 82%
for anhydrous ammonia to 16% for sodium nitrate. Regardless of
how it is applied, if the nitrogen is to be usable by plants it
must eventually exist as ammonium or nitrate.
Nationally, about 10.5 million tons a year, or 95 percent of
total fertilizer nitrogen, are used in agriculture. Sales have
increased dramatically from the three million tons applied in 1960
(see Figure 6) . The top 10 states in quantities of fertilizer used
are: Iowa, Illinois, Nebraska, Texas, Missouri, California,
Kansas, Indiana, Ohio, and North Dakota, in that order. They
account for over 58 percent over the nation's fertilizer N usage,
largely because of their extensive acreages of corn, sorghum, and
wheat (Vroomen, 1989).
Application Rates
Application rates on various crops are an indicator of where
commercial fertilizer might be an important source of
contamination. Corn has the highest application rates of any field
crop, on the order of 140 Ibs/acre nationally, almost twice the
rate used on the next most intensive field crops, cotton and
sorghum (Figure 8). About 38 percent of all fertilizer N sold is
used on corn (Figure 9). Intensity of use may be correlated with
precipitation—application rates per acre for a given crop tend to
be higher in regions receiving higher mean levels of rainfall. For
example, the application rate on corn in Indiana is 162 Ibs/acre
45
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46
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Figure 8
Estimated Consumption of Nitrogen, Selected Crops
Total 1986 U.S. consumption = 10.4 million tons N
140
Figure $ &
Nitrogen Application Rates, Selected Crops
67
70
73
76
79
82 85 88
Source: Vroomen, 1989
47
-------
* DRAFT (3/5/91) *
compared to 66 Ibs/acre in South Dakota. See Appendix E for mean
application rates and percentages of total N use in the major
producing states on several major field crops.
High value specialty crops, such as fruits, vegetables, and
ornamentals, involve only a fraction of the acreage of the field
crops, but they generally employ higher rates of N because the
incremental gain in value of the crop offsets the cost of the extra
fertilizer. Furthermore, because, as in the case of vegetables,
they require high levels of nitrogen at the stage of full growth to
achieve satisfactory yield and quality, excess nitrogen remains in
the soil at harvest (Schweiger, 1987). In addition, vegetables can
leave behind high nitrogen-containing plant residues (AGRA-EUROPE
37/88, 1988).
Despite their high nitrogen requirement, certain horticultural
crops, such as potatoes, are shallow-rooted and may not efficiently
use fertilizer once it starts downward in the soil profile.
Furthermore, they may require coarse-textured, relatively permeable
soils which permit greater leaching (Saffigna, 1977).
California and Florida agriculture account for a large share
of the total horticultural production in the country. In 1987,
California had 774,553 acres in vegetable production and 2,152,664
acres in orchards. Florida had 265,331 and 762,068 acres
respectively (U.S. Census of Agriculture, 1987). As much as 600
Ibs N per acres are applied to ornamental ferns. Florida's
Cooperative Extension Service recommends between 200 and 280 Ibs
N/acre for turfgrass, depending on species, 200 Ibs N/acre for
celery, 160 Ibs N/acre for tomato and pepper, 150 Ibs N/acre for
Irish potato, and 120 Ibs N/acre for muskmelon, watermelon, head
cabbage, sweet corn, strawberry and onion, etc. (IFAS, July 1989) .
In California, potatoes receive 225 Ibs N/acre, dates 200 Ibs.,
broccoli 238 Ibs., celery 315 Ibs., head-lettuce 204 Ibs., and
spinach 199 Ibs. Tomatoes, California's largest specialty crop in
terms of acreage, receives 128 Ibs N/ac. (Carmen and Heaton, 1977).
These are recommendations per crop season. Thus, if several crops
are grown in succession, as is commonly the case in Florida and
southern California, total application per acre for the year will
be considerably higher. High rainfall and specialization in these
horticultural crops cause Florida to have the highest consumption
of N per harvested acre of all states. California is sixth highest
state nationally in total nitrogen fertilizer usage.
Corn appears to be much more of a problem than other field
crops. In order to get a general idea of how much of the nitrogen
applied as fertilizer may be ultimately available for leaching and
run-off into water, one can subtract the N-content of the harvested
crop from the amount applied. Nationally fertilizer applied to
corn (5.1 million tons) is 1.7 million tons greater than the amount
48
-------
* DRAFT (3/5/91) *
of N contained in grain corn (3.4 million tons) (White, 1989).
This figure is somewhat of an overestimate since it fails to
account for denitrification and the harvest of corn for silage.
Much less residual nitrogen appears to come from other field
crops. For example, farmers applied 1.5 million tons of fertilizer
N on wheat and the harvested grain contained 1.2 million tons.
Thus, the applied tonnage of fertilizer N to wheat was 25 percent
greater than the N content of the resulting crop, while the
corresponding margin for corn was 50 percent (White, 1989). While
these numbers do not imply that all the remaining nitrogen is
available for leaching, they give an indication of which crops
could have the greatest potential for leaching.
Potential Hotspots for Fertilizer Use
Figure 10 differentiates counties across the country according
to county-wide estimates of the intensity of commercial fertilizer
applications to cropland. These data were generated by dividing
county-level fertilizer nitrogen sales figures for 1987 (US EPA
County-level Fertilizer Sales Database, 1990) by the number of
acres which farmers reported to have fertilized in 1987 (US Census
of Agriculture, 1987).
The figure shows, in light shading, counties in which the
estimated average rate of application of fertilizer nitrogen for
all crops was between 70 and 185 pounds per acre. The lower bound
of 70 pounds nitrogen per acre is the amount of nitrogen
recommended for a relatively low wheat yield goal of 40 bushels per
acre (Livestock Waste Facilities Handbook, 1985). The upper bound
of 185 pounds of nitrogen per acre is the amount of nitrogen
recommended for a relatively high corn yield of 150 bushels per
acre. As Figure 10 shows, wheat producing areas in the western
U.S. receive a relatively low rate of application compared to other
major field crops and non-leguminous crops, while corn is be the
most nitrogen-intensive of the major field crops.
Figure 10 identifies fertilizer as a very large source of N in
Midwestern and Eastern areas where analysis identified widespread
N pollution. Livestock waste represents a much smaller source of
N in these areas. However, cause and effect cannot be inferred, as
quantity of N applied to the land represents only part of the
picture. For example, N from livestock and septic systems may be
more directly available to enter ground and surface water.
irrigation
Irrigation, because it raises the recharge rate of ground
water, complicates the nutrient management problem, particularly in
the West where irrigation water is re-used repeatedly and used to
49
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* DRAFT (3/5/91) *
flush salts out of the soils. The water flushes out the N in the
soil. In addition, higher fertilizer application rates may be
correlated with irrigation. Heavily irrigated cotton in California
uses 118 Ibs/acre compared to 34 Ibs/acre for cotton in less
extensively irrigated Oklahoma. Irrigated corn in California
receives 192 Ibs/acre (Carmen and Heaton, 1977).
Specialty crops are generally irrigated, as they are grown
primarily in the arid west or where rainfall is often insufficient
for plant growth. Even in Florida, they are frequently irrigated.
Because of soil conditions and the unpredictability of rainfall in
the more humid areas, a significant amount of nitrate leaching is
probable regardless of irrigation practice (Pratt, 1984).
According to Keeney, H[t]he high probability of leaching, combined
with large nitrogen inputs, makes irrigated agriculture a major
potential source of nitrate to ground water." And, in fact, "[i]n
most cases [where high concentrations of nitrates in ground water
were found beneath irrigated agriculture] a close relationship
existed between the amount of nitrate leached and the amount of
fertilizer nitrogen used." Fertilizer use in irrigated agriculture
has been identified as the chief source of nitrate contamination of
ground water in the agricultural valleys of California, central
Nebraska, eastern Colorado, and in the sand plain region of central
Wisconsin (Keeney, 1986, p.280).
Chemigation
Chemigation, or as it is referred to with regard to nitrogen
fertilizer, fertigation, is the process of mixing irrigation water
with chemical fertilizer. This process can cause ground water
contamination through direct contamination of wells and through
over-fertilization which results in nitrate leaching.
Wells can be contaminated through Chemigation accidents. If
the backflow prevention device in the irrigation system fails.
Water mixed with chemicals can flow back down the well when pumping
stops. Potentially the entire contents of fertilizer tank could
siphon back into the well, losing as much as two tons of nitrogen.
In addition, because nitrogen is relatively inexpensive, farmers
may over apply nitrogen in irrigation water to assure a high yield
response. However, there is a high risk of over-application if
too much water is applied or if the water is applied after a rain.
A study of Chemigation in the Nebraska Sandhills showed that only
10% of the fertigation nitrogen was consumed by plants (Shearer, 19
). In some instances though, irrigation may be used to time
fertilizer applications more precisely so that fertilizer to the
plants when it can be used most efficiently.
51
-------
* DRAFT (3/5/91) *
Drainage
100 million acres of wetlands have been converted to cropland
by the installation of artificial drainage. Subsurface tiles can
be installed beneath cropland and either drain the excess water
into ground water through an agricultural drainage well or to
surface water through a series of pipes. Drainage to surface water
is by far the most common method. In the Delmarva Peninsula,
surface drainage is often employed. Farmers allow excess water to
flow across their fields into ditches that empty into surface
water. Studies conducted in the San Joaguin Valley in California
found that drainage water from tiled lands averaged 20 mg/1. Some
areas had levels between 100 and 200 mg/1 (California, 1971).
The likelihood of nitrate contamination of ground water is
lessened in areas where drainage water is diverted to surface water
bodies. Nitrate and associated problems are not transformed, but
merely transferred. Major tile drained areas in Ohio, Illinois,
Indiana, and Iowa may show little nitrate contamination in analyses
of drinking water wells. For example, northwestern Ohio, which has
the most intensive row crop agriculture in the state, has the least
amount of nitrate contamination in private drinking water wells
(Baker, 1990).
Cropland drained by agricultural drainage wells (ADW) may
present special ground water quality problems in areas of the
country where they are concentrated. An ADW is usually a buried
collection cistern into which subsurface tiles or pipe networks
drain water from fields to an aquifer. The wells often have
surface inlets from the surrounding farm land or a nearby roadway.
In the west, irrigation return flow is the principal waste disposed
through ADWs. A report by the EPA's Ada, Oklahoma laboratory
(1990) states that ADWs facilitate ground water contamination since
they inject contaminants, i.e. agricultural chemicals and road
salt, directly into aquifers.
A major study by the Iowa Department of Natural Resources and
the Department of Agriculture and Land stewardship is currently
underway to assess the impact of ADWs on ground-water quality. The
state goal is to prevent contamination of ground water from ADWs by
1995. Baker, et al. (1984) found that water entering ADWs
exceeded the nitrate MCL in 85% of the cases. Concentrations were
generally 10-30 mg/L nitrate between runoff events when almost all
drainage to the ADWs was from subsurface flow. A ground-water
transport model predicted influence of the ADW within 1 1/4 miles.
The study states that there is "strong evidence that nitrate in
recharge to ADWs, not surface infiltration, is increasing nitrate
concentration in aquifers." A large number of drinking water wells
that have rising nitrate levels are located in areas with ADWs.
Surface infiltration was ruled out in areas where the overburden
52
-------
* DRAFT (3/5/91) *
was greater than 15 meters. Since nitrate concentrations appear to
be very dependent on crop type and fertilizer application rate, the
current Iowa study may show that these concentrations are
overestimates. The final results will not be available until 1994.
Timing
While most fertilizer nitrogen is applied in the spring, a
significant amount is applied in the fall (28% of fertilizer
nitrogen is sold in the fall). This is not a cause for concern if
the fall application is immediately followed by a fall planting,
e.g. winter wheat. However, where there is a fall fertilizer
application not followed by planting until spring, there is an
increased potential for loss of N—frozen soils and frequent
precipitation will cause much of the N to run-off into surface
water and leach into ground water. Although the practice appears
to be declining, as many as 16% of farmers apply fertilizer in the
fall, but do not plant until spring (USDA Objective Yield Survey,
1988). Table shows total fertilizer sales broken out by spring
and fall transactions, by state (sales data tabulated by the
Tennessee Valley Authority's National Fertilizer and Environmental
Research Center).
Livestock Waste
In many regions dominated by livestock agriculture, livestock
wastes pose the greatest threat to water quality. Hallberg (1987)
asserts that even if nationally all livestock and poultry waste
could be recovered and applied to land, it would represent only 40
percent of nitrogen fertilizer application. Because 50 percent of
manure production is deposited diffusely by cattle and sheep
grazing on pasture and range (White, 1989), only the remaining 50
percent that is deposited in confined facilities (about 20% of
fertilizer N) can be manipulated (CAST, 1975; White, 1989;
Hallberg, 1990).
While the total production of manure nitrogen which can be
land applied may appear to be minor in comparison to fertilizer
nitrogen, the distribution of manure sources, both regionally and
locally, can play a crucial role in impairing water quality. As
the following tables indicate [TABLE 1A], animal production occurs
in all fifty states; however several key states in the Southeast,
Corn Belt, and Southwest account for the largest proportion of
total production, depending on the livestock type.
53
-------
* DRAFT (3/5/91) *
TABLE 1A
NUMBER OF ANIMALS IN INVENTORY IN 1987 (1,000'S)
AL
AK
AZ
AR
CA
CO
CT
DE
FL
6A
HI
ID
IL
IN
IA
KS
KY
LA
ME
MD
MA
MI
MN
MS
MO
MT
NE
NV
NH
NJ
NM
NY
NC
ND
OH
OK
OR
PA
RI
SC
SD
TN
TX
UT
VT
VA
WA
WY
WV
WI
BEEF
COWS
748.0
3.2
334.9
786.2
906.0
830.2
7.1
2.2
995.3
606.8
83.4
558.2
511.2
315.8
1,123.7
1,354.6
967.9
422.6
11.8
48.5
9.7
110.2
360.2
579.3
1,819.0
1,399.9
1,823.6
305.0
4.2
11.4
572.8
71.6
320.6
886.6
284.6
1,630.4
618.9
160.7
1.1
205.3
1,502.9
894.3
5,138.6
346.5
9.8
581.3
335.0
689.2
182.1
180.3
MILK
COWS
46.0
1.7
86.3
70.9
1,070.4
76.3
41.7
9.4
177.0
97.8
11.8
157.7
186.4
163.9
294.9
96.7
224.3
83.4
49.8
110.5
36.9
344.6
709.8
71.8
242.0
26.9
105.2
17.6
25.1
32.1
58.6
814.5
110.1
96.4
347.3
90.5
95.3
673.1
3.0
40.1
137.0
180.4
356.5
76.6
179.0
157.1
220.8
9.3
27.0
1.743.4
HOGS &
PIGS
353.1
0.6
135.4
452.9
150.9
258.7
5.4
49.7
156.1
1,060.4
47.6
76.9
5,643.0
4,372.3
12,983.1
1,516.9
838.5
51.9
9.0
197.2
25.8
1,227.1
4,236.5
179.1
2,582.0
200.7
3,944.2
16.5
5.0
32.0
44.2
99.6
2,547.1
294.4
2,059.2
187.4
86.3
919.8
4.7
352.4
1,750.2
774.5
527.9
33.6
5.1
345.1
59.2
28.4
30.8
1.312.8
SHEEP &
LAMBS
5.3
2.4
301.3
10.9
979.5
708.1
7.3
1.7
8.9
8.7
0.0
316.1
137.9
82.8
451.6
249.3
36.5
11.5
15.6
24.6
14.8
101.3
241.6
5.4
101.8
588.2
195.5
99.8
9.2
12.6
468.3
76.4
15.8
182.0
239.5
120.5
470.3
113.2
1.7
1.6
603.8
15.3
2,055.0
595.6
20.5
161.1
80.2
917.1
75.0
94.4
CHICKENS
3 MONTHS+
15,107.0
2.4
331.5
24,085.4
45,377.6
3,118.8
4,913.0
834.3
12,964.8
26,274.5
1,111.9
1,425.6
4,396.1
26,787.3
9,580.7
2,094.6
2,103.7
1,504.1
6,999.7
4,060.8
1,502.2
8,428.6
12,125.0
7,027.6
8,235.5
978.8
3,621.2
18.2
459.4
2,130.5
0.0
5,455.9
20,070.3
277.6
21,244.9
5,826.7
3,049.6
25,548.5
205.8
7,539.8
1,752.4
3,266.8
19,601.3
2,089.3
405.9
6,605.7
5,928.0
29.2
691.1
5.156.4
BROILERS
SOLD
564,583.5
4.1
NA
719,764.5
209,376.0
43.7
851.0
210,492.1
93,224.8
609,503.0
2,069.3
8.7
435.6
22,306.7
666.0
176.1
2,201.2
96,147.4
13,679.9
257,070.1
NA
702.4
27,356.2
276,652.3
40,991.2
84.7
911.0
0.5
NA
453.8
NA
1,713.6
408,721.1
52.7
8,967.7
89,704.4
14,244.4
106,382.3
58.7
60,295.2
237.8
75,974.5
226,038.1
7.8
5.2
142,971.8
36,068.9
9.5
29,226.9
10.761.7
US 31,652.6 10,084.7 52,271.1 11,037.5 372,245.7 4,361,198.3
54
-------
* DRAFT (3/5/91) *
The type of animal raised is a very important consideration in
nutrient management. For example, even though nationally, all
dairy cows produce more tons of manure than all laying hens, the
number of pounds of nitrogen in one ton of dairy manure which can
be used as a fertilizer is substantially less than that for laying
hens (see Table IB). These differences imply that on a farm-level
basis, substantially more land area is needed to efficiently
utilize poultry litter than dairy manure. Missouri classified
poultry litter and disposal as its major ground water quality
problem. The number of birds produced in the state is expected to
quadruple by 1995.
TABLE IB
PRODUCTION OF MANURE AND NITROGEN PER ANIMAL AND NATIONAL
PRODUCTION TOTALS (1987):
MANURE LBS N/
DRY TONS/ ANIMAL
ANIMAL
TOTAL
ANIMALS
ANIMAL
Dairy
Beef
Swine
Sheep
Layers
Broilers
1.89 123 10,084,697
0.77 61 31,652,593
0.21 32 52,271,120
0.18 16 11,059,397
0.0096 0.94 316,503,065
0.0065 0.78 4,361,975,630
MANURE
TOTAL
DRY TONS
19,060,077
24,372,497
10,976,935
1,990,691
3,038,429
28,352,842
NITROGEN
TOTAL TONS
620,209
965,404
836,338
88,475
148,756
1,701,170
SOURCE: Gilbertson (1979) and 1987 Census of Agriculture.
Farmers often view manure as a waste disposal problem rather
than a source of nutrients. Their primary concern is disposing of
the manure as economically as possible, with less concern for the
impacts the manure can have on ground and surface water. In these
cases, manure is spread on cropland simply to dispose of it. As is
the case with fertilizer N, when manure is spread in excess of crop
nutrient requirements (either directly or in combination with
fertilizers) or when the ground is frozen, excess nitrogen is
likely to leach into ground water or runoff into surface water.
Manure application generally presents more problems for the
farmer than application of commercial fertilizers for two main
reasons. First, the nitrogen content of manure is variable
depending on content of the feed, type of animal, volatilization
and denitrification rates, and management practices employed, i.e.
type of storage, whether or not manure is incorporated into the
soil. Second, it is more difficult to handle, especially because
of the large volumes (particularly dairy and swine slurries) needed
to obtain the same nitrogen content as fertilizers. Therefore,
farmers often do not spread their manure evenly across all their
55
-------
* DRAFT (3/5/91) *
fields. The fields closest to the barnyard tend to receive high
application rates whereas more distant fields may receive no
manure.
When inadequate provisions are made for manure disposal—
insufficient available land area to assimilate manure nutrients or
inappropriate storage facilities to retain manure during fall and
winter months—ground and surface water quality impairments are
likely to result.
Concentrated Livestock Production
The trend towards larger and more concentrated feeding
operations will result in "increased imbalances between nutrients
imported to feeding sites and nutrients exported" (White, 1989).
Table 3C provides some indication of the extent of large-scale
livestock production nationally.
TABLE 3C
LARGE-SCALE LIVESTOCK (PERCENTAGE OF TOTAL PRODUCTION):
1987
ANIMAL
SIZE NUMBER PERCENT PERCENT
CUTOFF OF FARMS OF FARMS OF ANIMALS
LARGER THAN LARGER THAN LARGER THAN
SIZE CUTOFF SIZE CUTOFF SIZE CUTOFF
Dairy
Beef
Hogs
Sheep
Layers
Broilers*
500
500
2,000
2,500
100,000
100,000
1268
4709
2809
685
561
1137
0.6%
0.6%
1.2%
0.7%
0.4%
4.1%
11.7%
14.6%
21.0%
34.2%
54.0%
24.3%
* Based on number of farms with sales of over 500,000; assumes
five groups of birds produced per year.
SOURCE: 1987 Census of Agriculture.
EPA recently estimated that 28 counties across the U.S. have
animal per acre densities which are so great that even if all the
nitrogen needs of the most nutrient-demanding crop, corn, were
supplied totally by manure, excess levels of nitrogen and
phosphorous would be available for environmental degradation of
56
-------
* DRAFT (3/5/91) *
water resources (see Figure II)4. If farmers undertook the
agronomic practice of supplying half their nitrogen needs from
manure and half from commercial fertilizer (to conserve phosphorous
and potassium), over 100 counties would meet this criterion, based
on manure production. This preliminary analysis suggests that not
enough land area is available for assimilating manure nutrients in
areas of high livestock density. Therefore, off-farm uses of
manure must be considered.
In large-scale animal feeding operations, the large amounts of
manure produced can lead to high nitrate concentrations in the
ground water under some conditions. Where the feedlots are located
in areas with a deep water table, the risk of contamination is
minimized in the short term (Scalf et al. 1973 from Patrick, Ford,
and Quarles, 1987).
Animal Waste Storage Ponds
Currently, a debate exists over whether animal waste lagoons
constructed to store manure so it will not be applied in the fall
or winter are responsible for nitrate contamination of ground
water. According to a 1977 EPA study, "heavy manure accumulations
may produce an impermeable mat, which in turn produces anaerobic
conditions that favor denitrification. Thus nitrate is
volatilized, and little infiltration takes place" (Patrick, Ford
and Quarles, 1987). However, research regarding earthen storage
ponds indicates that these facilities can leak under situations
associated with drawdown of manure and freeze/thaw cycles (EPA,
Region 6, 1989). Channels created by earthworms migrating through
the wetted perimeters of earthen storage ponds may also be a source
of leaching. As a result of these concerns, the Wisconsin
Department of Natural Resources worked with the Soil Conservation
Service in Wisconsin to modify the national standard and
specifications for earthen storage ponds in the state (Weinberg,
1990). Revised standards and specifications have also been
developed in Texas and Louisiana.
Abandoned Feedlots
Active feedlots and barnyards are not a major source of
nitrate to regional ground water aquifers, however, abandoned or
seasonally empty feedlots are likely to leach nitrates (Keeney,
1986). Other researchers state that feedlots pose no danger of
4 The amount of total N available by acre was calculated by
dividing the total number of pounds of nitrogen available from
manure by the number of harvested cropland acres minus those
cropland acres producing N-fixing crops. This figure was compared
to the N uptake per acre for corn.
57
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* DRAFT (3/5/91) *
ground water contamination in the southeastern states due to the
soil's ability to denitrify the wastes (Miller, et al., 1977).
Furhiman and Barton (1971) linked ground water contamination by
bacteria, viruses, and nitrate to poultry and hog farms in Arizona,
California, Nevada, and Utah (Patrick, Ford, and Quarles, 1987).
Nonpoint Source Surface Runoff From Fields
Many manure-related impairments of surface and ground water
originate from nonpoint sources. For example, manure nutrients may
move off cropland and pastures which have received manure
applications which are in excess of crop/grass nutrient
requirements. Second, even in relatively small livestock
operations, manure runoff can be significant, particularly where
livestock are free to trample and defecate in and along streams and
ponds (Beyerle, 1990). Third, runoff from animal loafing areas,
such as those associated with dairy operations, can be damaging
because daily trampling eliminates vegetative cover which would
otherwise take up manure nutrients or, more importantly, control
movement of runoff to surface waters. Fourth, to the extent that
relatively small pastures or areas where livestock continually
congregate are unmanaged and overgrazed, manure will more readily
be available as a water pollutant.
Legumes and Green Manures
Some researchers (see Smith et al., 1986; Huntington, et al.,
1985) proposed that legumes, which have the ability to convert
atmospheric nitrogen to a form usable by crops, could minimize
nitrate leaching in comparison with commercial fertilizers. Green
manures (crops grown for their nutrient value and then plowed
down) , similarly were hypothesized to have less leaching potential.
However, evidence on the rate of nitrate leaching from legumes is
inconclusive (Russelle and Hargrove, 1989) . Legume cover crops can
provide significant fertilizer-N for subsequent crops, but there is
no definitive data on the fate of legume-N. Organic sources of
nitrogen such as animal manures or legumes can create significant
problems with nitrate leaching.
Greenhouses and Nurseries
The intensity of production on most greenhouse and nursery
land uses makes these operations another likely source of nitrate
in ground or surface water. Greenhouse operations employ among
the highest rates of any land use, as high as 600 to 800 Ib
N/acre/year (White, 1990), and in 1979, covered approximately
10,000 acres, each operation averaging two-thirds of an acre. White
estimates there are probably about 17,000 acres today. Greenhouses
have been implicated in several areas as the cause of nitrate
concentrations that significantly exceed the MCL. The Monterey
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* DRAFT (3/5/91) *
County Soil and Water Conservation District associated nitrate
levels of over 20 mg/L and in some cases, up to 60 mg/L in the
ground water of two hydrologic subareas with greenhouse operations.
Greenhouse operations in Salinas Valley, California (Snow, 1988).
California has both the highest number of horticultural specialties
establishments (2,265) and the greatest acreage of floriculture
under greenhouse cover (2,532 acres). In number of establishments,
California was followed by Florida, Pennsylvania, New York, and
Ohio, (White, 1990).
Agri-Chemical^Dealers
There are more than 14,000 individual retail fertilizer
dealerships in the United States. While data are not available on
a regional or national basis, anecdotal data exist which indicate
that excessively high nitrate concentrations in ground water and
well water can occur from nitrogen fertilizer spills at mixing and
loading areas. A recent survey by the Illinois Department of
Health indicated that agri-chemical mixing and loading facilities
presented a definite threat to ground water with levels of nitrate
in proximate ground water far exceeding the federal drinking water
standard. Random testing of 1500 licensed agri-chemical dealers in
Illinois showed that for 80 sites most of the wells (more than 60%)
associated with the site had nitrate levels exceeding 10 ppm (Long,
IDPH, 1987). The reasons cited for this contamination included
unsuitable conditions for storing large amounts of chemicals,
improper mixing, loading, and disposal of chemicals, and running
agrichemical practices on relatively small parcels of land without
taking the necessary environmental precautions.
The pollution scenario identified in the Illinois survey is
not unique. Ten case studies in the Corn Belt showed a pattern of
high nitrate, pesticide, and ammonia concentrations associated with
agrichemical dealerships. Some shallow private wells in the case
study areas had levels of nitrate over 115 ppm. Hallberg noted
that these sites should be considered "quasi-point sources" because
"even though they are discrete sites, there are literally thousands
of such facilities across the Corn Belt, so their potential impact
could be widespread" (Mueller, 1989).
The pattern of contamination was similar at each dealership:
equipment was rinsed and flushed into drainage ditches and left to
leach into the ground. This type of problem is equally likely to
occur on farmsteads where farmers load and rinse their equipment in
the same place each year (Richard Fawcett of the Iowa State
University Extension Service). Naymik and Barcelona (1981)
describe how leaching from an uncovered fertilizer bin at an
Illinois plant caused groundwater contamination of 2,100 mg/L
ammonia and 1,800 mg/L nitrate.
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NON-AGRICULTURAL SOURCES
Non-agricultural sources of nitrogenous compounds represent
small additions to the environment, but locally they can create
serious contamination problems. They fall into four basic
categories: a nutrient added to fertilize grass, a human waste
product, a by-product of industry, or a result of fossil fuel
combustion. The importance of any of the sources depends on
conditions in the local area. Aerial sources are somewhat
different in that they can travel greater distances in a short time
period.
Septic Systems
Septic systems are the most frequently reported cause of
ground water contamination in the United States (Yates, 1985). 41
states have identified them as a major source of ground water
contamination in the state (Moody, 1990). For example, New Mexico
reported that household septic tanks and cesspools are the single
largest source of ground water contamination (New Mexico Water
Quality Control Commission, 1988). The California State Water
Resource Control Board estimates that six percent of nitrate ground
water pollution comes from septic systems (Anton, 1988). Septic
systems represent the largest source of wastewater discharged into
land by volume, 820 to 1460 million gallons a year (Scalf, 1977).
Over 21 million homes, representing approximately one-third of the
population of the United States, rely on septic systems for
sanitary waste disposal (Office of Housing, 1987 data). 25 percent
of all new home construction or an additional 500,000 systems are
installed each year.
Septic system density is a far more important indicator of
probability of contamination than the total number of systems. The
highest densities of septic systems occur in high growth areas.
Figure 13 shows the density of septic systems throughout the United
States. The Boston to Washington, D.C. urban corridor, parts of
Florida, and areas around urban centers especially in the east all
have high septic system densities. EPA considers any area that has
over 40 septic systems per square mile (1 per 16 acres) to be
potential areas of ground water contamination. This assumes that
the systems are spread out evenly. A greater problem would occur
if the systems were clustered.
Four counties have over 100,000 housing units served by septic
systems: Los Angeles, California; Dade County, Florida; Nassau and
Suffolk Counties, New York, ranging from over 25 to 346 per square
mile. An additional 23 counties have over 50,000 septic systems,
generally ranging from 20 to over 250 per square mile. 15 counties
have at least 100 per square mile. These statistics do not take
into account the area available for each lot. Nassau county has
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the highest density in the country with over 350 systems per square
mile (US EPA, 1977).
Figure 14 shows a cross section of septic system operation. It
functions specifically to discharge waste water into the ground
water, using the soil as a filtering mechanism. Wastewater leaves
the house and flows into the septic tank. Sludge, grease, and scum
settle out and the effluent flows into a distribution box where it
is channeled to a soil adsorption field. There is virtually no
change in the total nitrogen content of wastewater as it passes
through the system. The anaerobic environment of the tank converts
the organic nitrogen in the influent from the house to primarily
ammonium in the effluent. Septic tank effluent averages between 40
and 80 mg/L of total nitrogen. 75 percent in the ammonium form
(NH4) and 25 percent as organic nitrogen (Reneau, et al., 1989).
The septage, or solids that are pumped out of the septic tank, has
a much higher nitrogen content up to 700 mg/1 total nitrogen
(55 FR 47241).
Optimally operating septic systems are conducive to the
nitrification of the ammonium to nitrate in a short distance from
the soil adsorption field. Generally very little denitrification
occurs in systems installed in well drained soils (Reneau, et al.,
1989). Therefore much of the nitrate produced is available to
leach into the ground water. Nitrate is not filtered out by the
soil: it moves with water. EPA (1980) estimates that approximately
18 to 32 mg/L nitrate enters the ground water. Walker, et al.
(1973) estimated that each household (family of four) results in
approximately 73 pounds of nitrate added to the ground water each
year. On a national scale, septic systems contribute about 350,000
tons of nitrogen to the ground water annually.
Contamination of ground or surface water by septic systems can
be an individual or a local problem. An individual drinking water
well may be poorly constructed or sited and allow the infiltration
of nitrate and other contaminants such as bacteria and viruses.
The local housing density may overwhelm the ability of the ground
water to dilute the nitrate to sufficiently low concentrations or
the local hydrogeology may be inappropriate for septic system
installation. The placement of septic systems is very site
specific. Many factors should be considered: depth to ground
water, permeability of the soil, slope, subsurface geology,
climate, vegetation, and number of users. Some studies estimate
that up to one half of the United States is inappropriate due to
one or more of these factors.
Urban Sewage
On a national scale, municipal sewage treatment plant effluent
is not a large part of nitrogen input to waters. However, in some
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areas, such as the Chesapeake Bay or Santa Ana River in California,
it is a very important source.
Publicly owned treatment works (POTWs) collect and centrally
treat sewage in areas where on-site septic systems are
inappropriate due to restrictive site conditions or higher density
development. More than 15,500 POTWs are currently in operation.
With the exception of some 1,800 non-discharging ponds and land
treatment systems, most POTWs discharge their treated effluent into
surface waters on a fairly continuous basis. About 29 billion
gallons per day (gpd) of combined domestic and pretreated
industrial wastewater are currently treated and discharged by POTWs
nationwide. These facilities range in size from less than 10,000
gpd to over one billion gpd in treatment capacity. Fewer than 500
treat over ten million gpd. A wide variety of treatment processes
are used by POTWs, although the most common are ponds, activated
sludge, and trickling filters (EPA, 1988, Needs Survey).
POTWs that discharge their effluent to surface waters receive
National Pollutant Discharge Elimination System (NPDES) permits to
meet state water quality standards which, with only a few
exceptions, specify a minimum of secondary treatment. However,
conventional treatment plants are not designed to remove total
nitrogen (ammonia and organic nitrogen) from the effluent.
Primary-secondary plants generally remove no more than 30 to 40
percent of the nitrogen.
Nitrogen levels in municipal wastewater effluents not required
to remove nitrogen frequently amount to as much as 25 mg/L or more
total nitrogen (which may be mostly ammonia or nitrate, depending
upon the type of treatment process used). Once discharged to
receiving waters or applied to the land, most of the nitrogen will
convert relatively quickly to nitrate.
Land Application of Sewage Sludge
In 1982 there were at least 2,463 publicly owned treatment
facilities applying liquid and thickened sludge on land surfaces,
and an additional 485 facilities in operation or under construction
using sludge spray irrigation practices (OTA, 1984). Of the 6.8
million dry tons of sludge produced by municipalities in 1982, 24%
to 29% was spread directly onto crops (OTA, 1984). The purpose of
land treatments is to biodegrade the organics and to immobilize the
inorganics" (Patrick et al., 1987). While land application of
sludge is considered a pollution prevention technique, examples
exist where farmers have failed to follow best management practices
such as reducing commercial nitrogen fertilizer when sewage sludge
has been applied to their fields. Elevated groundwater nitrate
concentrations as high as 35 mg/L have resulted.
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* DRAFT (3/5/91) *
Non-Farm Use of Fertilizer
Home Lawn Care
Non-farm use of nitrogen fertilizer is estimated to account
for about 4.2% (425,000 tons of 10.2 million tons in 1987) of total
nitrogen fertilizer use (White, 1989). Regionally, non-farm use is
most significant in New England (34% of total fertilizer use), Mid-
Atlantic (19%), and Pacific Coast (12%) (White, 1989). It is used
on golf courses, home lawns, and turf on commercial, industrial,
institutional and multi-family residential facilities. While these
uses represent a small percentage of total use, non-farm uses of
fertilizer have been linked to ground water contamination in a
number of areas: home lawns on Long Island (Flipse, 1984) and golf
courses on Cape Cod (Cohen, 1990).
Privately conducted surveys indicate that about 425,000 tons
of nitrogen fertilizer (4.0% of the total) were used on turf and
gardens (Stangel, 1987). There are about 32 million acres of turf
on residential and commercial sites in this country (Consumers
Union, 1990). Runoff of N applied to turfgrass has been found to
seldom to occur at concentrations above the MCL, but there are
instances where water draining from turf to ground water may attain
levels that approach or exceed the MCL, (Petrovic, 1990).
A survey of Long Island households indicated that homeowners
were applying on average 122 Ibs/acre to their lawns (Koppelman,
1978). Professional lawn care applicators may apply significantly
more, on the order of 196 Ibs/acre to 261 Ibs/acre (Morton, et al.,
1988). At least one study found that nitrogen leaching and runoff
from turfgrass based on rates typically applied by commercial
applicators are not significant (Angle, 1990). In the same study,
however, twice the commercial rate of application, caused
significant runoff. Angle suggested that many homeowners managing
their own turf expect lawns to look 'twice as good1 for twice the
fertilizer application (Varner, 1990).
Further, Morton et al. (1988) found that while controlled
irrigation did not increase nitrate concentrations leaching from
fertilized turfgrass relative to concentrations from unfertilized
plots, irrigation at higher rates did degrade the drainage water.
Just as homeowners are thought to apply fertilizer in excess of
recommended rates, they may also over-water their lawns. Excessive
fertilization compounded by improper irrigation appears to pose the
most likely scenario for nitrate concentrations above the MCL
draining from residential turf.
Golf Courses
Golf courses typically receive higher annual rates than home
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* DRAFT (3/5/91) *
lawns, estimated to be between 218 to 260 Ibs/acre (White 1989),
although these are often applied as frequent light applications
that may reduce the potential loss to ground water. Rates vary
widely between areas on a course: on Cape Cod, available data for
four golf courses shows average rates of 100 Ibs/acre on fairways,
118 Ibs/acre on tees, and 187 Ibs/acre on greens (Cohen, et al.,
1990). A 1974 Florida turfgrass survey found that rates of
application on all areas of golf courses in the state averaged 188
Ibs/acre, but were 747 Ibs/acre for golf course greens (Snyder,
1982). There are approximately 12,000 golf courses across the
nation (Cohen, et al., 1990).
Nitrate leaching from highly sandy golf greens have been
observed to increase as the rate of fertilizer application
increased, while on fine sandy loam soils, the concentrations did
not increase significantly as the rate of application was increased
(Brown, et al., 1977). Considerably less nitrate leaching was
observed to occur from applications of activated sewage sludge and
ureaformaldehyde, a slow-release fertilizer.
Sources
The two major sources of aerial nitrogen oxides are industry,
especially electric utilities, and automobiles and other vehicles
through the burning of fossil fuels and the resulting emissions of
NOX and SO2. Each sector contributes about half of the total.
The National Acid Precipitation Program (1987) estimated that 28%
of NOX emissions came from power plants. The primary controlling
factor of the rate of NOX emissions from these sources is the
combustion temperature of the process. The 20th century trend for
man-made NOX is increasing in almost direct proportion to the
amount of fossil fuels burned. Since the passage of the original
Clean Air Act, NOX has increased about seven percent, the only
conventional air pollutant to show an increase.
No clear national picture exists concerning the influence of
atmospheric deposition of nitrogen compounds on estuaries and
coastal waters. Denitrification from these waters is the most
important process controlling the fate of nitrogen, but it is so
variable that generalizations may not be useful. (For example, on
a single farm, denitrification rates can vary by a factor of 100.)
In order to discern the role air plays, it is necessary to
calculate a mass balance. The Environmental Defense Fund (Fisher,
et al., 1988) originally estimated that one-third of the nitrogen
loadings to Chesapeake Bay were atmospheric in origin. Atmospheric
deposition enters estuaries through two pathways, one is deposition
deposited directly to the surface of the water, and the second is
deposition to the upland watersheds which contributes, to a poorly
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* DRAFT (3/5/91) *
defined extent, to the runoff from those watersheds and then
through the streams to the estuaries. The nitrogen in this runoff
can contribute to the eutrophication of surface water without
leading to significant environmental problems in upland forests.
EPA then made estimates for four other areas. The percentages
show extreme variation: Narragansett Bay, 10%, New York Bight,
37%; Upper Potomac River Basin, 68%; and Ochlockonee Bay, Florida
(almost a completely forested watershed), almost 100% (EPA, 1990).
A more recent study that calculated a mass balance for the Upper
Potomac River Basin estimated that while atmospheric deposition
represented 42 percent of total nitrogen inputs, over two-thirds of
the nitrogen fell on forested land which is able to assimilate the
additional nitrogen (Groffman and Jaworski, 1990). Jones and Lee
(1990) calculated a mass balance for Lake Tahoe (a nitrogen-limited
lake) and concluded that automobile emissions are the primary
source, representing over 80 percent of the nitrogen load. There
are many uncertainties involved in these estimates, but they point
out the possible impact of atmospheric sources of nitrogen on the
health of these areas.
EPA has developed a research plan to analyze the long-term
ecological risk to coastal waters from atmospheric deposition, in
response to a Congressional request. The purpose of the plan is to
provide information for pollution control decision makers that
considers the ecologic impacts of nitrogen on estuaries. The plan
estimates that 1000 work years would be necessary to gather
adequate information.
The Great Lakes Water Quality Board (1989) believes that the
major source of nitrogen loading to Lake Huron and Lake Superior is
atmospheric deposition because both lakes have limited agriculture
on surrounding lands and low population densities. It may be
impossible to discern the contribution of atmospheric nitrogen to
the loadings of the other Lakes because of the number of other
possible sources.
Atmospheric deposition has also been observed to lead to high
levels of nitrate in ground water. In the San Gabriel Mountains
near Los Angeles, California, ground-water concentrations from
nearby, relatively unpolluted watershed were typically one to three
orders of magnitude lower (Riggan, et al., 1985).
Industrial Sources
Food Processing Wastes
Some nitrogen is returned to fields in the form of solid
wastes from food processing operations. While the amount of
nitrogen supplied in this manner is small in aggregate, estimated
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* DRAFT (3/5/91) *
to be on the order of 15,000 tons, excluding brewery, dairy, and
slaughterhouse wastes (NFPA,1989), it can be a significant source
in areas surrounding large processing facilities if the nitrogen
content of the waste is not considered when applying fertilizer.
This situation is likely to be encountered most often in the
western united states, due to the volume of processing waste
generated and the types of produce that are processed.
Cleaning and washing at processing plants generate liquid
wastes or high moisture sludges. Liquid wastes are usually
discharged to a POTW or to water directly. Sludges are usually
disposed of in landfills or by field application. In some
operations, substantial quantities of solid waste are culled from
raw produce or screened from wastewater and used as a soil
amendment. Generally, solid wastes from food processing contain
about one percent nitrogen.
Other Industrial sources
As compared to the estimated 10.5 million tons of fertilizer
nitrogen, the contribution of nitrogen from inorganic industrial
wastes appears to be a rather small source to land. It is more
significant as a source of nitrogen to surface water where 23,800
tons actually reaching surface water is the equivalent of a much
greater amount of fertilizer nitrogen applied to land, only a
portion of which will be transported to surface water.
The industrial process which produces the greatest amount of
nitrogenous waste is the synthesis of ammonia, which is used to
produce other nitrogenous compounds including fertilizers, nitric
acid, and paper products (Madison, 1984). Dischargers of
significant quantities of nitrogen include ammonia dealers,
fertilizer manufacturers, and manufacturers of explosives. Nitrate
concentrations of 500 mg/L or greater can result from explosives
production (New Mexico Water Quality Control Commission, 1988).
Nuclear fuels manufacturers are also a potential source of high
concentrations of nitrates. For one month in 1988, a plant in
Virginia discharged on average, 360 mg/L nitrate to surface water
(Virginia State Water Control Board, 1988).
Host larger industrial facilities are required under the
Emergency Planning and Community Right to Know Act of 1986 to
report releases of all toxics listed on EPA's Toxics Release
Inventory (TRI). The four major sources of nitrogen in the TRI
database are ammonium nitrate (solution), ammonia, nitric acid, and
ammonium sulfate (solution). The TRI lists releases directly to
water, to air, to land, to POTWs, by underground injection, and by
other off-site transfer.
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* DRAFT (3/5/91) *
Outlined below are releases that present the roost likely
impacts to surface and ground water.
Nitric Acid fHNO3l ; The 1988 figure for releases to water is 1,622
tons of nitric acid. Releases of nitric acid to air were 5,491
tons, to POTWs 11,661 tons, and 714 tons were reported released to
land.
Ammonium Nitrate (NH^NCX) ; 82 percent of the 4,411 tons of ammonium
nitrate releases directly to water are facilities which
manufacture, import, or process nitrogenous fertilizers. Other
industrial classifications which released ammonium nitrate in
significant quantities directly to water include fertilizer
mixing-only operations, paperboard mills, explosives
manufacturers, and industrial inorganic chemical vendors. Releases
to land were 8,373 tons, approximately twice the releases directly
to water. Total releases to POTWs were 3,798 tons.
Ammonia fNH3); The TRI database reports 10,244 tons of ammonia
released directly to water. This total is believed to be greatly
underestimated, because reporting requirements have required
facilities to report only the amount of un-ionized ammonia.
Beginning 1990, facilities will be required to report both the
total of ionized (NH4+) and un-ionized ammonia. The following
types of facilities reported the largest releases: industrial
organic chemicals vendors, blast furnaces and steel mills,
petroleum refiners, agrichemical manufacturers, primary metals
facilities, and pulp and paper facilities.
Releases to air were 123,842 tons. Air releases of ammonia
from industrial facilities may result in a significant amount of
air deposition of nitrogen downwind of a facility. A reported
total of 12,169 tons were released to POTWs, and 3,052 tons were
released to land.
Ammonium Sulfate ((NH^KSO^ ; 35,123 tons of ammonium sulfate were
released directly to water in 1988 from the following industries:
inorganic chemical dealers, pulp and paper mills, primary metals
facilities, and fertilizer manufacturers . Total releases to land
were 7,203 tons, and 95,504 tons were released to POTWs.
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POLLUTION PREVENTION
The goal of pollution prevention is to avoid pollution
problems before damage becomes more serious and costly to remedy.
Action is needed now because nitrate contamination represents the
most pervasive problem affecting ground water (Water Quality 2000,
Agriculture Committee, 1990). Moreover, nitrogen is known to cause
eutrophication of estuarine and marine ecosystems, and some lakes.
Pollution prevention may offer fairly rapid hope for
estuaries. The Chesapeake Bay, and perhaps other estuaries as
well, can cleanse themselves of excess nutrients in years, not
decades, once the sources of nitrogen have been controlled
(Boynton, 1990). There is no similar rapid mechanism to cleanse
aquifers once they have been contaminated by nitrate. Pollution
prevention methods, therefore, can prevent the loss of a valuable
ground water resource—used for drinking water and as a source of
recharge to surface water bodies.
Pollution prevention includes the development of sustainable
technology and education or low cost, market incentives, as well as
more expensive cost-sharing and regulatory programs. Relatively
inexpensive pollution prevention practices can be implemented while
pollution problems are being further assessed. Prevention is
particularly suited to N problems because numerous sources often
make it infeasible to pinpoint the cause of a problem. Since
competition for resources even for low-cost options will remain
intense, despite recent funding increases, the pollution prevention
strategy considers economics and the likely economic acceptability
of proposed technologies. Innovative strategies have been
developed to deal with excess nutrients in the Tar-Pamlico area
that allow pollution trading between point and non-point sources
(Harding, 1990).
Pollution prevention strategies are discussed for the
following major sources of nitrogen: agriculture—fertilizer on
cropland and livestock waste; and non-agriculture—septic systems,
urban sewage, industry, and non-farm use of fertilizer.
AGRICULTURE
Fertilizer, used to encourage crop growth, is a major source
of nitrogen in virtually all areas experiencing widespread nitrogen
contamination. The most intensively fertilized cropland is found
in grain production in the Corn Belt (particularly Iowa, Illinois,
Indiana, Nebraska, and Ohio) and in specialty crop production in
states such as California and Florida. Throughout the major crop
producing regions, virtually all farmers need assistance in
managing fertilizer.
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Livestock problems tend to occur in the localities where the
total amount of manure in a county exceeds the nutrient requirement
of all crops grown in the county (Figure ), or at the many
scattered sites where livestock are located on or near surface
waters. Prevention efforts need to recognize the pervasive nature
of fertilizer problems (Canter, 1987), as well as the concentrated
nature of many livestock sources. Prevention efforts must also
recognize that fertilizer provides a valuable resource to farmers
that leads to abundant and affordable food.
Both crop residues and livestock waste are used as a source of
nutrients in conjunction with commercial fertilizer. Although crop
residues account for an important, but variable, part of the K
(Meisinger, 1984, p.399), fertilizer application supplements what
is provided by these residues. Additions of commercial fertilizer
compensate for discrepancies between crop N needs and N from
residues. Similarly, fertilizer use is likely to supplement N
from livestock waste, except in areas where livestock densities are
so high as to provide all of the N requirements. Even on farms
with considerable livestock, management must focus as much on
chemical fertilizer N as on livestock waste, since fertilizer is
the input most readily subject to accurate measurement and
management. Proper use of fertilizer requires accounting for the
fluctuating nutrient value of crop residues, manures, sewage
sludge, and mineral N in the soil in order to determine an
agronomically sound amount of N to be applied as commercial
fertilizer.
In areas where livestock sources of N dominate, improving the
efficiency of fertilizer use often increases farmers' net returns
(Follett, 1989; Fox, et al., 1989; Blackmere, 1989; Bouldin, 1971),
while improving storage structures for livestock waste management
more likely represents a net loss to the farmer (Crowder and Young,
1987). Important exceptions include such low cost practices as
manure testing, manure spreader calibration, and more frequent
hauling to the fields. Pollution prevention efforts must address
interrelated fertilizer and livestock sources of N.
Pollution prevention needs may differ for surface versus
ground water. N is particularly a surface water problem in
estuaries, such as the Chesapeake Bay, which are adversely affected
by livestock sources of phosphorus as well as nitrogen. Some
management practices for reducing livestock N from ground water
interflow to surface water also reduce phosphorus losses; by
preventing pollution from two pollutants at once, livestock waste
management may be especially effective in programs addressing
surface water pollution from N. Surface water pollution often
originates far from where the damage occurs, emphasizing again, the
need to target programs to the geographic area where the livestock
N originates (EPA, Region 3, 1983).
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Management Practices for Commercial Fertilizer
Many management practices have been developed to limit the
amount of fertilizer nitrogen leaching into ground water (U. s.
Congress, 1990). However, a fundamental problem in managing N
fertilizer results from the considerable variation over time in the
amount of N in the soil. Rainfall events in spring and winter
leach N below the root zone where plants can use it in ways that
are hard to predict in advance. Fertilizer applications need to
coincide with periods of rapid plant growth if plants are to use
the N. Accurate N use recommendations are also needed which take
into account N available from the previous year's crop.
Two best management practices (BMPs) for avoiding potential
leaching of nitrogen below the root zone are most often emphasized
in the literature: (1) timing of fertilizer application through
split preplant and summer side-dress applications (Bouldin, et al.,
1971) and (2) soil testing (Johnson, 1986; Meisinger, 1984; North
Carolina Extension Service, 1982; Water Quality 2000, Agriculture
Committee, 1990). Related practices which should be pursued
include: setting appropriate yield goals, testing manure for N
content, plant tissue testing to determine N needs, computer
simulations using more complex models, and irrigation water
sampling for N content.
Excess nitrogen accounts for much of what leaches through the
root zone, representing an economic loss to the farmer as well as
the major source of pollution to ground water and potentially
surface water. Although many BMPs have been designed to address
N problems specific to conditions in certain regions, reducing the
excess application through improved soil testing and through timing
fertilizer applications are needed virtually everywhere that N
pollution from intensive crop production occurs. Soil testing
potentially makes the greatest contribution in livestock producing
areas where accounting for N from legume crops and livestock waste
poses special problems.
Timing
Fertilization with chemical fertilizer or manure must occur
when plants can best utilize the nitrogen. A single application of
fertilizer before planting can increase the potential for
contamination of ground water since plants cannot immediately use
the nitrogen and spring rains may leach the unused nitrogen.
"Split" applications improve the timing. A lower initial preplant
application in early spring is followed by side-dressing fertilizer
N in early summer after the rains. Side-dress applications are
placed between rows of plants. This important practice has proven
itself both in research on experimental plots and in actual use by
farmers. Side-dressing used in combination with soil testing for
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* DRAFT (3/5/91) *
N availability in the soil helps to avoid having substantially more
nitrogen available in the soil at any time than plants can use.
Timing applications through split, preplant and summer side-
dress applications helps minimize N leaching by reducing the amount
of N fertilizer in the soil during the spring months' heavy rains.
These rains occur before crops are mature enough to use the N.
Farmers' use of split, summer side-dress application has not
reduced fertilizer use as much as the one-third reduction achieved
on experimental plots (Bouldin, Reid, and Lathwell, 1971). Yet,
farmers who side-dress do use much less fertilizer per acre each
year than do all farmers combined (Table 1) . Currently, 25 percent
of U.S. corn farmers apply split, preplant, and summer sidedress
applications (Taylor and Vrooroen, 1989).
TABLE 2
Average N use on corn, all farms/split application farms, 1988.
All Farms
Farms Splitting
Applications
Percent
Difference
Illinois
Indiana
Iowa
Missouri
Ohio
South Dakota
pounds N/acre,
163 131
146 131
139 131
132 110
158 112
80 45
20
10
6
17
29
44
Source: Objective Yield Survey. 1988. Economic Research Service,
U.S. Department of Agriculture. Data provided by Harold Taylor.
While one-quarter of all farmers side-dress, 16 percent of
farmers apply some fertilizer in the fall for their spring planted
crops (Taylor and Vroomen, 1989). Fall application is especially
likely to increase N leaching because of the considerable
precipitation which occurs in winter when plants are often not
available to use the N.
Nitrogen Soil Tests
In 1984, researchers successfully employed soil nitrogen tests
in humid states in the late spring to support summer side-dress
applications of fertilizer. These tests actually measure the N
availability in the soil for plant growth. Previously, virtually
all humid states (which basically exclude the Western states) had
relied on N recommendations based on the farmer's cropping history,
soil type, and yield goal (Magdoff, 1984; Meisinger, 1984). New
technologies for late spring soil testing both support use of the
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side-dressing BMP and provide a soil test where it has not been
available previously.
Because of tremendous variability in the amount of N remaining
in the soil from the previous year's crop and from mineralization,
farmers tend to apply much more fertilizer than plants can use
during any but unusual weather. OVer application of N as insurance
is somewhat costly, but supplying too little N before a very wet
spring apparently reduces many farmers' profits enough, in the
absence of the late spring soil test, to pay for the routine,
excess application. Similarly, lack of information leads many
farmers to ignore the fertilizer available from manure and legume
crops even though legumes provide considerable N by N fixation and
in some instances supply much more than the following crop can use
(Fox and Piekielek, 1983; Meisinger, 1984, p.410; El-Hout and
Blackmer, 1990).
Soil tests for arid states, particularly Nebraska and Montana,
were developed earlier than in humid states, presumably because
spring rains in humid areas introduced considerable uncertainty as
to how much N leached out of the root zone through the season; this
is not a problem in arid states. However, a survey of state soil
fertility extension experts identified lack of calibration of the
tests as the major factor impeding the dissemination of soil
testing technologies to farmers (Meisinger, 1984). Thus, lack of
resources for soil test calibration was a problem even before the
breakthrough in late spring soil testing, and it continues to be a
problem. Calibration involves "tuning" soil tests for differences
in soils and climate which affect N needs.
In spite of the need for more resources to begin calibration
or improve site specific calibration of soil tests, the land grant
university system routinely provides soil test information to
farmers. Reaching farmers with improved soil test technologies
should pose relatively few institutional challenges. Tractor
mounted soil testing technology (Colburn, 1990), still in
experimental stages of development, may further streamline delivery
of tests, and make these technologies far more effective, as
fertilizer needs vary within fields. These tractor mounted testing
devices have a computer which uses the results of continuous soil
tests to instantaneously adjust fertilizer application to the needs
of each part of the field.
Economically and Environmentally Optimum Use Rates
One issue for those developing new soil tests is whether they
should be calibrated for economic efficiency. Recommendations to
maximize yields will lead to greater fertilizer use than will
recommendations geared to maximizing profits. (This is because N
costs money and at yield maximizing rates, costs exceed added
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returns from more N).
Plants' use of N depends on how much grain can be produced on
a particular soil. The higher the expected yield, or "yield goal,"
the more N is needed by plants to meet that goal. Setting
realistic yield goals (which are in the formula used in making soil
test recommendations) is thus essential to obtaining
environmentally and economically efficient N use. By avoiding
excessive fertilizer use, farmers will more closely equate
applications to plant needs. It is the excessive applications
beyond what plants can use that are primarily responsible for
pollution and for economic waste. However, not providing enough N
to meet plant needs greatly reduces yields, profits and ultimately,
the availability of food.
Keeping records of yields, yield goals, fertilizer use, and
fertilizer recommendations is critical to maintaining realistic
yield goals. These records also assist those advising farmers on
fertilizer use, facilitating evaluation of the performance of each
year's use of N.
Whether more economically efficient use of fertilizer by U.S.
farmers will eliminate the potential of fertilizers to pollute is
a question that EPA and USDA need to explore further. However,
careful fertilizer management can substantially reduce the
pollution without reducing profits (Ayer, 1989).
other Nitrogen Management BHPs
Other practices proposed for managing fertilizer to reduce
nitrogen pollution fall into three major categories: 1) managing
surface runoff, usually through soil conservation practices, 2)
managing water, itself, through improved irrigation and drainage
practices, and 3) managing crop rotations and crop mix to reduce
the production of crops requiring fertilizer. These three
categories of practices are important in certain locations but not
recommended as widely to address N pollution as are soil testing
and timing practices described above.
Soil Conservation Managing surface runoff through practices
like terracing, contour plowing, and ridge tillage on the contour
reduce N runoff into surface water, but often at the expense of
increasing infiltration of nitrogen into the ground water (Kramer,
Hjelmfelt, and Alberts, 1989). Since ground water pollution (or
ground water interflow to pollute surface water) is the more
pervasive N problem, practices for managing surface runoff are
often not the appropriate remedy for N pollution, in spite of their
importance in reducing sediment and phosphorus pollution from
erodible land. Nitrate does not attach to soil particles like
phosphorus does, therefore soil conservation practices have little
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effect on nitrate loadings.
An exception is vegetative filter strips along streams or
marshes. Filter strips are generally viewed as a BMP to filter out
pollutants in surface runoff using grass, weeds, and tree litter,
but filter strips also reduce pollution from N through nutrient
uptake and by aiding denitrification (Lowrance, et al., 1984).
Thus, this practice does not trade surface water pollution for
ground water pollution as other practices designed to reduce
surface runoff.
A closely related practice is a winter cover crop which in
mild climates will "scavenge" nitrogen left from the previous crop.
* DRAFT (3/5/91) *
of humus, can leach from the fallow ground between rows (Sturm,
1987) . The pollution prevention technique of growing a ground
cover, such as grasses, between rows of trees or plants serves to
"scavenge" N and other nutrients in the bare soil between the rows.
In addition, they contribute over time to replenishment of the
organic matter of soil (humus) (Hempler, 1990).
For vegetables, the period of greatest potential nitrate
losses can occur shortly before or after planting when the soil is
largely bare and amount of mineralized nitrogen exceeds plant
demand. A pollution prevention technique is to maintain a
continual grass cover except for the area directly surrounding the
cash crop. Where this is not possible or economical, according to
Hempler, cover crops should be planted between cash crops to
prevent extended periods of bare ground.
Nitrogen Inhibitors Nitrogen inhibitors, a controversial BMP
candidate, are intended to improve the timing of fertilizer
availability to plants without requiring split applications, once
again, to conserve and efficiently use the fertilizer applied.
Inhibitors work by preventing bacteria from converting
ammonia fertilizer to nitrate that may be leached through the soil.
However, research is needed to verify that inhibitors work in a
predictable enough way to actually influence farmers' use of
fertilizer (Hauck, 1988). Inhibitors may have the undesirable
effect of encouraging fall applications which lead to leaching
(Hoeft,1984). Slowing the release of fertilizer may also reduce
leaching early in the season when plants are too small to use it,
only to increase leaching late in the season when it is too late
for efficient plant uptake (Allen, 1984). Inhibitors are being
regulated as pesticides because they are bactericides.
Implementation Issues
Fertilizer is quite amenable to prevention techniques. The
most prominent management practices for fertilizer aim to reduce
the need to apply extra fertilizer as "insurance" against risks
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include improved irrigation management, closing surface drain
outlets during winter, winter cover crops, and vegetated filter
strips. All of these low cost practices need to receive priority
in U.S. Department of Agriculture, Extension Service, educational
programs. In addition, State water quality programs, such as those
described below, alert farmers to the seriousness of these
environmental problems and encourage adoption of the relatively low
cost remedial measures.
Incentives
Farmers may adopt best management practices more rapidly when
the government shares the cost. Although universities often
subsidize soil tests for N (where tests are available), support for
these practices generally has been limited. Exceptions include a
$20 million USDA pilot program in 1989 which included some
fertilizer management cost-sharing in selected counties across the
U.S. Another major exception is a demonstration program in Iowa
funded by a state excise tax on fertilizer.
Technology Development and Education The Iowa program subsidized
adoption of fertilizer BMPs indirectly by contributing hundreds of
thousands of dollars per year to the development and calibration of
improved soil tests, including a test based on the late spring soil
test by Magdoff (1984). Calibration takes three to five years and
requires an investment this large only in the major agricultural
states such as Iowa. States with less extensive agriculture can
calibrate soil tests for less. By reducing fertilizer use by a
third, it is believed that simply developing and making this
technology readily available represents a substantial financial
incentive for its adoption (Business Publishers, Inc., 1990). In
Pennsylvania, introduction and promotion of carefully calibrated
fertilizer recommendations coincided with a gradual rec ction in
fertilizer use, reaching nearly 50 percent reduction over 8 years
(Ogg, 1990) .
Education programs, which in Iowa and in the Pennsylvania
pilot program included cost sharing for hiring private consultants
as well as demonstrations and other educational services provided
by the USDA Extension Service, also provide an incentive to adopt
new technologies. The combined approaches of technology
development, education, and cost sharing are mutually supporting
programs that are particularly effective where new technology
development is a key element in addressing the problem. Clearly,
new technologies and their development must be a critical
ingredient of a successful N management program.
Farmer interest in these voluntary approaches may be enhanced
by their own concerns with providing safe water for family and
livestock use. Farmers must also be conscious with possible
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liability regarding potential pollution of neighbors1 wells.
Taxes and User Fees Taxing fertilizer to reduce use represents
another option. However, a fairly large tax, or user fee, would be
required to substantially reduce fertilizer use. Fees are used
also to pay for technology development to better manage N, as in
the Iowa example. Fees may be used to internalize (make polluters
share the cost) the damages caused by N pollution. It is doubtful
that these user fees would themselves be sufficiently large to
greatly affect use, unless fees as large as 50 or 100 percent of
the price farmers pay are adopted (Dubgaard, 1987).
Reducing Price Distortions from Farm Programs Farm programs
have been blamed in the past for encouraging farmers to seek higher
yields in order to enhance program payments. Past yields are built
into the price support payment formula, thereby increasing
fertilizer use in the past contributing to the multi-billion dollar
price support payments received by farmers (Hertle, 1990; Ogg,
1990).
However, yields used in computing payments have been frozen
since 1985. By avoiding raising program yields to achieved yields
on farms, program administrators have sent the message that higher
input use does not lead to higher payments. Continuing this policy
will avoid creating a strong incentive to apply more N fertilizer,
while preventing price support/supply control programs from
undermining their own price support objectives (Hertle, 1990).
Regulation of Fertilizer Use
There are few laws currently regulating farmers' use of
nitrate fertilizer in the U.S. In Nebraska where nitrate
contamination of ground water is a serious problem, the state's 23
Natural Resource Districts (NRD) have the authority to regulate
nitrogen fertilizer use to reduce groundwater pollution. Arizona
is also currently implementing a new permit program that requires
farmers to adopt BMPs.
State Programs
Nebraska The Central Platte NRD has established an aggressive
three-phase program to control nitrate concentrations in ground
water, which is the primary drinking water source for all residents
within the District. The program is divided into three phases
depending on nitrate levels found in the Districts monitoring
wells: Phase I, 12.5 ppm; Phase II, 12.6 to 20 ppm; Phase III, 20
ppm.
Most of the District currently is in Phase I which emphasizes
voluntary deep soil and irrigation water sampling for nitrate to
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determine the amount of carry-over available to the crops. The
only regulated action under Phase I is the banning of fall
applications of commercially applied nitrogen fertilizer on sandy
soils.
Phases II and III place more regulatory controls on farming
operations in those areas of the District with higher nitrate
levels are found. In Phase II areas (currently 500,000 acres),
farmers are required to have an annual nitrate water analysis for
each irrigation well, an annual deep soils analysis, delayed
applications of commercial fertilizer, and required attendance at
District-approved educational programs designed to explain the
hazards of nitrogen contamination and provide techniques to reduce
nitrogen usage.
Phase III controls have not yet been triggered in the
District. When nitrogen levels reach the Phase III threshold, both
Phase I and Phase II restrictions continue, and additional controls
on commercial nitrogen fertilizer would be implemented.
Nebraska's approach to controlling nitrogen use is influenced
by several factors generally not found in other states: strong
local regulatory authorities (NRDs), a relatively dry climate with
little risk of wet soil conditions preventing a split application
of nitrogen, the availability of a reliable soil test, and
relatively little legume crop acreage which is a more difficult N
source to measure.
Arizona The Regulated Agricultural Activities Program
established under the Environmental Quality Act of 1986 requires
farmers to use N management BMPs as a condition of a general
permit. If farmers violate the general permit by failing to adopt
BMPs, they can face enforcement actions or be required to apply for
an individual permit which can contain stringent stipulations. The
Program establishes general goals for best management practices for
nitrogen fertilizer and animal feeding operations. The goals
require farmers that apply fertilizer to use application, timing,
placement, irrigation, and tillage practices that minimize nitrogen
loss. Farmers choose the specific practices needed on their farms
to achieve these goals from the Program handbook. Concentrated
animal feeding operations are required to collect, stockpile, and
dispose of manure; control and dispose of nitrogen-contaminated
water associated with large storms; and close facilities in ways
that minimize discharge of nitrogen pollutants and are economically
feasible (Munson and Russell, 1990).
Wisconsin In Wisconsin, livestock operations too small for
permitting programs are nonethelf 3 subject to regulation, but only
if someone complains that such Deration causes a water quality
problem. Complaints lead to a visit by an environmental expert and
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an agricultural expert. If an actual problem exists, fanners
become eligible for a 70 percent cost share grant, which according
to a Wisconsin Department of Agriculture, Trade, and Consumer
Protection "Status Summary" (January 12, 1990), they have elected
to receive in half of the verified complaints. A fourth of farmers
address the problem at their own expense. Another 10 percent await
possible judicial action. (Action was not required for the balance
of the cases).
Actual regulation is difficult under the Wisconsin program,
because, unlike the programs described for other states, the farm
in question must be the cause of a problem. Most programs require
farmers to follow certain practices, rather than establishing
blame. However, the Wisconsin program targets a perceived water
quality offender, offering the program the advantage of a sharp
focus. Also, even this program's very modest threat of regulation
has led to remedial action by the implicated farmers in 90 percent
of the complaints. Complaints generally are limited to surface
water problems, which are more visible than ground water problems.
Toxic Substances Control Act EPA has broad authority under
Section 6 of The Toxic Substance Control Act (TSCA) to require
farmers to adopt specific best management practices for nitrogen
fertilizer application. Section 6 gives EPA the responsibility to
control manufacturing, processing, distribution in commerce, use or
disposal of a chemical substance or mixture if it "presents or will
present an unreasonable risk of injury to health or the
environment." If EPA finds that there is a reasonable basis to
conclude that the use of nitrogen fertilizer presents or will
present an unreasonable risk, it may promulgate rules prohibiting
or otherwise regulating any manner or method of its commercial use
(TSCA §6 (a)(5)). Such rules could, for example, condition use of
fertilizers in compliance with farm level nitrogen management
plans, use of soil tests, and adoption of a variety of best
management practices, including volume and seasonal application
restrictions, fall cover crop planting requirements to limit
leaching and education/certification requirements for farmer-
applicators. They could also include requirements for fertilizer
dealerships such as handling, storage or disposal requirements, to
protect against risk from spills or dumping.
Under Section 4 of TSCA, EPA may require industry to test a
chemical substance or mixture if the Administrator finds that it
"may present an unreasonable risk of injury to health or the
environment." If EPA decides that it lacks important information
about toxicity or exposure with regard to nitrates, it can specify
what information the industry must provide, through additional
testing if necessary.
One of the goals of EPA's chemical control program under TSCA
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is to encourage greater product stewardship. EPA has been actively
working with chemical companies, trade associations, and other
interested constituencies to encourage safer handling of chemical
substances and mixtures throughout their life cycle. Fertilizers
containing nitrates clearly fit in this category. The Agency could
consider both regulatory and non-regulatory means to promote
greater care of such substances in their manufacture, use, and
disposal.
Agricultural Drainage Wells Unlike cropland without artificial
drains, EPA has regulatory authority over wells that inject
directly into ground water. Agricultural drainage wells (ADWs) are
regulated by EPA under the Safe Drinking Water Act. They are
considered Class V underground injection wells. Current
regulations authorize these wells to operate by rule if 1) their
existence was reported to the States or EPA within the specified
time and 2) they do not contaminate an underground source of
drinking water to the extent that it would violate an MCL or
otherwise endanger public health. Most ADWs were not reported. An
EPA workgroup has been formed to develop more specific regulations
and guidance for Class V wells.
In the 1987 Report to Congress on Class V wells, only 1,338
ADWs were reported nationwide. This figure grossly underestimates
the number of ADWs. For example, one Idaho study reported 2,000
wells on the east Snake River plain alone. Iowa initially reported
only 230 wells, but now estimates that about 690 exist.
Various options have been suggested to control contamination
of ground water from ADWs. The most drastic remedy would be to
close the wells. The land could continue as cropland with a
concomitant decrease in yields or be converted to wetlands either
through easements or eminent domain. Funds to buy significant
amounts of land would be very difficult to obtain. Land drained by
ADWs in the Iowa study was valued at $3,000 to $4,000 an acre.
Alternate drainage to a surface water discharge is also a
possibility. This option could adversely affect the surface
waters. Estimates of the cost of providing the drainage range from
$100 to $440 (1983 dollars) an acre depending on the distance to
drainage facilities and the need for pumps. Use of fertilizer and
leachable pesticides on the drained cropland could also be
proscribed.
An option under consideration in the current effort to develop
Class V regulations is mandating the use of BMPs to decrease use of
agricultural chemicals on 1) all land drained by the ADW or 2) just
land near the well. BMPs are effective when employed on all
drained land. When BMPs are only used on land adjacent to the
well, nitrate contamination is decreased only by the percentage of
the total acreage affected.
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Other strategies exist for controlling contamination by
surface water runoff into ADWs, but they would not significantly
affect the level of nitrate in the wells (Baker, et al., 1984).
Nurseries and Greenhouses
The Texas Water Commission has written permits for four large
wholesale nursery operations in east Texas in response to public
complaints. The operations need not be discharging from a
discrete conveyance in order for a permit to be required. Host
discharge from these operations occurs during storm events and in
cases where discharge occurs through sheet flow, the agency may
require that some conveyance be built which could then be monitored
(Holderread, 1990).
The permits, in addition to prohibiting detectable pesticide
discharge, contain limits on the discharge of ammonia and nitrate.
The limits are set on a site-specific basis, depending on the
designated uses of the stream receiving discharge. One operation
for which the Commission wrote a permit was a 480-acre tree farm
and other horticultural specialties operation. On this operation
there were three distinct point from which discharge occurred.
Another operation for which a permit was written was in the process
of developing a slow-release nitrogen management plan. Monitoring
data is typically required on a quarterly basis.
Wastewater from greenhouse operations may reach surface or
ground water in a variety of ways—underground injection, direct
discharge to surface water, discharge to a POTW, or percolation to
ground water—depending on the design of the greenhouse. Injection
into a well can be controlled under SDWA. In addition, it should
be possible to regulate some greenhouses—those with a
"discernible, confined, and discrete conveyance"—under the NPDES
program (though the exemption of irrigation return flows under CWA
may pose a legal question). EPA may need to provide technical
assistance to the States in developing permits for greenhouses.
Greenhouses discharging to POTWs may in some cases be required
by the POTW to pre-treat, but it is not known to what extent such
requirements are in place. Pre-treatment requirements are often a
function of the size of a POTW—large POTWs tend to require
pre-treatment more often than small ones. However, even with large
industrial discharges to POTWs, nitrate levels are rarely a
criterion in pre-treatment.
Greenhouses allowing percolation to ground water present a bit
of an anomaly in terms of the source/non-point source break out of
pollution sources. While not a point source in the sense of
discharging through a pipe or other conveyance, many of these
operations are very small—greenhouse operations nationwide average
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two-thirds of an acre (White, 1989). Best management practices
that are suitable for greenhouse operations should be developed.
Design criteria might also be developed and approved by EPA,
concerning siting, irrigation systems, and water re-use.
Livestock Waste Management
In many regions of the country dominated by livestock
agriculture, livestock wastes pose the greatest threat to water
quality. Pollution prevention from livestock must be
comprehensive to prevent water quality degradation from the most
significant polluters, regardless of whether they are large-scale
feedlots which may be issued permits as "point" sources or more
numerous small operations traditionally unregulated as nonpoint
sources.
Concentrated Livestock Facilities
In addition to the diffuse source impairments described above,
runoff from manure and wastewater accumulated in the feeding areas
of many livestock operations may be covered in the National
Pollution Discharge Elimination System (NPDES) program. Under this
program, operators of concentrated animal feeding operations must
construct a storage structure for all wastes and wastewater that
come from the feeding operation.5
According to the 1987 Census of Agriculture and the USDA report
Cattle on Feed, there may be as many as 5,000 to 10,000 livestock
operations that meet the 1,000 animal unit criterion. However, the
number of NPDES permits issued is thought to be substantially less.
To the extent that there are more concentrated feedlots than the
number of NPDES permits already issued, further regulatory efforts
may be needed.
Given that a potentially large number of operations need
permits, the NPDES authorities need to raise the priority of this
program and develop a strategic approach. The NPDES authority
might consider issuing individual permits to only the largest
confined operations. (A good place to start might be the highly
concentrated poultry industry because less than one percent of the
laying hen producers account for 45 percent of production and less
5A concentrated animal feeding operation is defined as having:
1) more than 1000 animal units (equivalent to 1000 beef cattle);
2) more than 300 animal units and a discharge directly into surface
waters; or 3) operations with fewer than 1000 animal units which
are determined through regulatory procedures (40 CFR Part 122.23
(c)) to cause significant water quality impairment.
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than one percent of the broiler producers account for 60 percent of
all broilers.) The remaining universe of concentrated feeding
operations could be covered by general permits. A general permit,
which outlines certain manure management requirements, could be
issued to all facilities in a certain geographic area. Compliance
with the permit would be up to the feedlot owner/operator, however,
if the facility is found to be discharging outside of permit
conditions, a notice of violation would be issued and a remedy
would be sought.
The NPDES authority should also consider working with the
nonpoint source authority in the state to identify the watersheds
with the most significant water quality problems caused by
concentrated feedlots. According to preliminary Clean Water Act
§319 Assessment data, approximately 32,706 lake acres and 4,827
river miles in 39 states and Puerto Rico were impaired by feedlots.
(The other states grouped all categories of nonpoint source
impairments such as feedlots, irrigation, chemicals, sediments
together in one category under "agriculture". Consequently, there
may be additional livestock impairments.) Once the NPDES
authority has these watershed-specific data, the authority may then
issue an individual permit, if the facility is very large, or a
general permit to cover all facilities at once because issuing
individual permits would be burdensome. The nonpoint source
authority can also assist in the NPDES program by identifying which
operators are not meeting the terms of their permit.
Through issuing a permit, the NPDES official requires farmers
to alter their manure management systems to meet the zero discharge
guidelines in 40 CFR Part 412, the effluent guideline for
concentrated feedlots. The nonpoint source authority can assist
farmers in seeking available cost-share assistance (either through
the USDA, Clean Lakes Program, Chesapeake Bay Program, the §319
demonstration programs, or through various state programs) to limit
pollution potential.
Surface Water Runoff from Fields
Several options are available to limit these forms of nonpoint
source pollution. To minimize movement of manure nutrients from
cropland and pastures into surface and ground waters, farmers
should consider crop nutrient needs, the nutrient value of manure,
as well as other sources of nutrients (commercial fertilizer,
legumes, and sludge) when applying manure to cropland. Proper
storage, testing of manure, and calibration of spreading equipment
should be encouraged (either through regulation, education, cost-
sharing or a combination of these measures). Where manure supplies
exceed nutrient requirements of the crops, given the extent of land
area to be covered, composting or exporting of manure to other
areas should be pursued.
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To limit: stream and pond disturbance due to direct access of
livestock to such waters, fanners could install electric high
tensile wire fences along streams and provide environmentally sound
stream crossings. Currently, the Pennsylvania Game Commission and
the USDA Agricultural Stabilization and Conservation Service (ASCS)
are working together to promote the use of solar-powered tensile
fencing to minimize maintenance, because traditional barbed wire
fences accumulate a great deal of debris.
To aid in keeping livestock out of streams, alternative water
sources such as spring-fed watering troughs could be installed. In
Maryland, the EPA Clean Lakes Program provided funds to demonstrate
that installing these water sources will reduce animal trampling
along streams and ponds because the cattle prefer to drink from
troughs. These troughs are encircled with wide concrete pads to
further reduce runoff of sediments and manure.
Furthermore, researchers at several land grant universities
are investigating the effectiveness of rotating cattle among
several smaller sized loafing areas to allow vegetative cover to
regenerate. By enhancing vegetative growth, farmers can limit
runoff of manure and sediments to streams. Similarly, the Soil
Conservation Service (SCS) together with the land grant
universities have developed small-scale intensive grazing systems
to segment and more effectively manage grazed pastures. These
systems maximize forage production to meet livestock management
needs, while also providing fallow periods which allow pastures to
regenerate.
To limit the concentration of nitrogen in manure, farmers
could reduce the nitrogen content of feed for livestock and more
closely calibrate the nutrient content of feed to the nutritional
needs of the livestock. This approach has been taken in the
Netherlands, both regarding nitrogen and phosphorous as a pollution
prevention technique.
Another method which can be used in conjunction with each of
the management practices described above is to install gutters and
adequate drain pipes around all barns and machine sheds. This
practice keeps clean water, clean and can be extremely beneficial
during heavy rain storm events.
Ground Water
Many feedlot management techniques can also be employed to
reduce the threat of contamination from manures. They include
altering the animal stocking rate and density in a given area,
removing manures from holding areas and applying to neighboring
fields and pastures at appropriate fertilization rates to account
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for differences in soil types and crop needs (Patrick, Ford, and
Quarles, 1987). Keeney (1986) reported that nitrate leaching from
land application of manure can be controlled by denitrification
through managing readily degradable organic material. Farmers
should test manure as well as account for nutrient demands of the
crop and the type of soil receiving the application. The farmer
should also be aware of how specific conduits, such as sinkholes
and abandoned wells, can affect local manure management.
Guidelines on animal waste storage ponds and manure storage
management need to be developed and implemented consistently across
NPDES, the SCS programs, and states, while taking into account
variations in geology, hydrology, and soils. To minimize the
threat of leaching, the staff recommend using a liner of
recompacted clay eighteen inches thick. It should extend up to
cover all exposed sand layers. If the storage pond is located
within 100 feet of a drinking water well, further precautions may
be necessary. In those instances where a liner is not needed,
siting the ponds in areas with low-permeability natural materials
is crucial. These materials should "not allow more than about 300
gallons of leakage per day per half acre of lagoon" (Chesney,
1990).
Implementation issues
NPDES Program The NPDES program for feedlots appears to be a low
priority given NPDES efforts to control other industrial point
sources. However, to the extent that the NPDES program for
feedlots is implemented, great care must be taken to ensure that
storage structures required under NPDES do not encourage ground
water contamination.
The NPDES program also should be evaluated to determine the
extent to which permits issued under this program cover not just
storage but also land application. To the extent that land
application controls are not included in permit, EPA may need to
revisit the NPDES program and effluent guidelines to identify how
this practice could be included.
Policies Regarding Farm or Regional Manure Surpluses The recent
trend in livestock production has been toward large-scale
concentrated feeding/production operations. This trend is driven
in part by economies of scale which states: as the size of the
operation increases, the per unit cost of production decreases.
Options for managing farm and regional imbalances of livestock
waste are limited by economics. Because manure, particularly dairy
waste, is very bulky and heavy due to a high moisture content,
affordable opportunities for its large-scale transport to other
farms or even to central processing facilities is limited. Should
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an economical market be available for using the manure as an energy
source (either on-farm or for regional use) or composting the
manure for commercial application, this problem would be reduced.
Recent projects show promise, however. For example, Clevenger
and Kraenzel identified wholesale garden uses, retail garden uses,
and agricultural uses for 7,200 tons of manure that would
accumulate annually as a byproduct of utilizing the manure in a
large-scale methane plant in New Mexico. Further research is
needed in the areas of drying or composting the manure on site to
reduce volume and weight.
Runoff and Infiltration from Land Application of Properly Stored
Livestock Wastes While the NPDES program is useful for shifting
manure from unmanaged piles into controlled storage structures, no
farmer is specifically required to undertake further BMPs to manage
these wastes once they have been taken out of storage. Therefore,
farmers may encourage runoff and leaching of these wastes if they
apply them to cropland at rates that are in excess of crop uptake
or during the most environmentally unsound times of the year (e.g.,
winter).
Even if off-farm export of manure is not required to adjust
for farm-level manure imbalances, farmers can undertake several
options to control runoff from their operations. First, the farmer
should test the soil (where possible) and the manure, as well as
identify the nutrient value of legumes to determine how much manure
and commercial fertilizer to apply. When applying the manure, the
farmer should attempt to incorporate it immediately into the soil
in order to prevent runoff. Furthermore, manure should never be
applied to land if no crops will be grown. To avoid nutrient loss,
other basic handling guidelines include 1) never leave stored or
piled wastes uncovered, 2) never pull spreaders across muddy
fields, 3) never allow manure to ferment in warm weather, and 4)
never spread manure on snow, steep hillsides, banks along streams,
ponds, or on farmland adjacent to wells (Pennsylvania State
University, n.d.).
Regulatory Programs A regulatory program to control N from
manure should focus on the total management of animal wastes and
wastewater. In addition, storage of wastes, land application of
wastes, and management of cattle around streams and other waters
must be considered. The regulatory program must also encompass
both ground and surface water protection. To achieve this goal, the
NPDES program must be amended to go beyond mere surface water
pollution through a conveyance and from large-scale facilities.
Other regulatory programs beyond the NPDES program could also be
proposed.
The modelling applied by EPA's Region 6 ground water program
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should be considered when designing storage structures. EPA should
ensure that this methodology is consistent with other federal
efforts, i.e., SCS technical assistance. Furthermore, given the
large number of facilities which may need to manage their manure,
the regulatory program must be targeted, beginning with the most
environmentally unsound facilities.
Incentive-Based Programs Managing manure presents a doubly
difficult situation. Many facilities need to alter their storage
and management practices and most storage and management practices
require a relatively large-scale capital investment. How should
EPA, the states, and USDA proceed? First, we need to evaluate what
our previously spent resources have achieved, i.e, Clean Lakes,
Chesapeake Bay, Agricultural Conservation Program (ACP) cost-share.
Then, we need to identify where further voluntary cost-share
efforts, if warranted, should be targeted. One criterion for
targeting could be §319 data on livestock related impairments.
Given the trend toward large-scale animal production, we need
to be identify how best to utilize surplus manure stocks. This
concern could be addressed through more research, however, it
appears that opportunities for composting and energy production may
be viable in certain regions. Where surplus stocks are
particularly problematic, water quality managers should become
aware of and be prepared to address any institutional, economic,
and cultural impediments to promoting a more even distribution of
animal wastes.
Composting
Composting is a method used to decompose livestock manure
under controlled conditions into a stable humus product. Volume
and weight reduction are achieved through loss of water and carbon
dioxide during the composting process. This smaller mass exhibits
an earthy odor, and can be more easily applied on-site, or
transported off-site, compared to raw manure. The distance which
the compost can be economically transported will depend on the
relative value of the compost, the distance to market, and the cost
of transport.
By composting manure, the likelihood of rapid release of
nitrogen from the compost is reduced since the more available forms
of nitrogen are stabilized or volatilize during composting. When
compared to raw manure and most fertilizers, composted manure
slowly releases nitrogen since almost all of this nutrient is in
organic forms. The organic nitrogen must be converted to inorganic
ammonium and oxidized to nitrate to become available to crops.
This conversion leads to a slower release of nitrates. There is
also a reduced potential leaching of nitrates as crops utilize the
nitrogen as it becomes available. However, the relative impacts on
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nitrate leaching and crop yields have not yet been fully determined
for annual applications of composted and uncomposted manures.
Chicken carcasses, in particular, are the subject of research
into composting. The Delaware Cooperative Extension Service has
developed recipes involving the use of whole chicken carcasses in
order to generate a compost product.
Agri-Chemical Dealers
Some states currently have or are considering regulations
dealing with fertilizer storage at dealerships, however there are
no federal guidelines or regulations. California, Wisconsin,
Kansas, and Iowa all have bulk fertilizer containment laws
(Simmonds, 1990).
The National Fertilizer and Environment Research Center
(NFERC) of the Tennessee Valley Authority (TVA) has developed an
information and education program for fertilizer dealers to ensure
improved environmental performance. 20 model facility
demonstration sites are planned nationwide to demonstrate practices
and technologies that are workable, cost-effective, and able to
meet state regulations. NFERC has also designed a self-
administered environmental checklist. It will also conduct site
assessments of facilities for a $3,500 fee.
NFERC has recognized that dealers are reluctant to spend money
to upgrade their facilities especially when this action might put
them at a competitive disadvantage with other dealers (NFERC,
1990). Federal regulations of fertilizer dealers would eliminate
this constraint.
European Programs
High levels of nitrate in water as a result of agricultural
activity became a major environmental issue in Europe with the
enactment of the European Community (EC) Drinking Water Directive
in 1980. The directive set regulatory limits for contaminants,
including nitrate, in drinking water to be achieved by 1985.
Eutrophication of the North and Adriatic Seas, in large measure
from nitrate transported through aquifers to surface waters,
created a demand for broader protection than necessary solely to
protect drinking water supplies. 60 percent of the nitrate loading
to the North Sea has been estimated to have come through ground
water (Deutscher Bundestag. 1990). Nearly every country in the EC
was not in compliance with the directive and began developing
initiatives to protect existing and potential sources of drinking
water from agricultural activities. European programs offer models
for U.S. policy since they differ considerably in design and the
degree to which they have been implemented.
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Unnaturally heavy loadings of nitrate and ammonium into the
environment have been a byproduct of European agricultural
productivity (von Weizsacker, 1989). In Denmark, 6 percent of the
population receives water above the drinking water standard and
this number is rapidly increasing (Institute for European
Environmental Policy, 1989). In West Germany, five percent of
delivered drinking water exceeds the standard (Merkel, 1985). Two
percent of population are exposed to levels above the standard in
France (French Ministry of Agriculture, 1988) . In the Netherlands,
average nitrate concentration of 106 mg/L are found in ground water
at 30 meters below sandy soils.
Nitrate Policies in the European community
The European Commission recognizes the limitations of member
state programs and the necessity of establishing a level playing
field with regard to agricultural competition within the EC. Water
suppliers have been reluctant to invest in denitrification plants,
governments have been reluctant to impose controls on farmers, and
control strategies have been politically sensitive. Member states
with strong environmental advocacy organizations, such as West
Germany, the United Kingdom, and the Netherlands, have taken steps
to implement controls on agriculture to protect ground water
resources, but, in so doing, have put domestic producers at a
competitive disadvantage with producers in other member states with
weak environmental advocacy groups and hence weak enforcement of
environmental protection.
Drinking water purveyors and environmental organizations have
urged the EC to promulgate a directive to control nitrate pollution
to ensure fair competition among agricultural producers in
different member states (Merkel, 1985). The draft directive,
expected to be promulgated in 1991, proposes to require Members to
establish nitrate sensitive zones (both surface and ground water)
and establish rules for good agricultural practices within those
zones (Baldock, 1989). The rules govern livestock stocking
densities, storage and application of slurry, application rates and
practices for fertilizers, nitrogen emission limits from sewage
treatment works, and record-keeping for the zones covering
fertilizer use, manure application, livestock densities. All EC
governments will be obliged to designate vulnerable zones within a
period of two years. Controls will need to be in place within four
year period.
EC environmental policy embodies two key principles. 1) The
generator of the pollution (including farmers) is held responsible
for the costs of preventing and eliminating nuisances, with some
exceptions. 2) Efforts should be made to prevent pollution rather
than expending resources to treat the contaminated water (Office
for Official Publication of the EC, 1987).
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In addition, there are attempts change agricultural policy to
bring it into harmony with environmental policy. A draft directive
allows member states to pay farmers to be multifunctional and to
de-intensify and to extensify production. In other words, farmers
would be compensated for adopting practices that are less
ecologically harmful. Finally, there would be a tax on fertilizer
to pay for education and outreach and where possible to dissuade
farmers from certain activities (Manale, 1991).
The EC system implicitly incorporates an important watchdog
role for non-governmental organizations (NGOs), such as
environmental advocacy groups. If a member state fails to
implement EC directives, an NGO in the member state may bring suit
against the offending government. As part of the remedy, the
government may be forced to detail how it will comply with the
European Community Directive to the satisfaction of the plaintiff
(Office for Official Publications of the EC, 1987).
Programs of Key Individual Member States
Certain guiding principles underlie the nitrate strategies of
all key member states. The supply of nutrients during the growing
season must conform to crop requirements, with an allowance made
for the soil nitrogen. There must be utilization of residual
mineral nitrogen through crop rotation and proper selection of
crops. The measures for achieving reductions in ground or surface
water loadings must be adapted to specific localities (United
Kingdom Ministry of Agriculture, 1990a). The major differences of
the programs lie in the manner in which these principles have been
incorporated into control strategies and the differing emphases on
voluntary and education measures as opposed to regulation.
The United Kingdom The government water authorities and private
water companies are drawing up individual programs for compliance
with the standards. These plans, which may include changes in land
use practices, denitrification plants, and blending of water
supplies, are submitted to the Ministry of the Environment for
approval (United Kingdom Ministry of Agriculture, 1990b). The
Ministry evaluates the effectiveness of these plans with computer
models capable of simulating nitrate leaching and movement to
ground water. The models estimate whether existing land use
practices in the catchment will lead to exceedance of standard and
how much reduction in leaching is necessary through a reduction in
the intensity and area of arable cropping and an extensification of
grassland management fWasserhaushaltsgesetz. 1986).
Plans for fertilizer control have been proposed only in
"nitrate sensitive areas," where the standard is being exceeded or
is at risk of being exceeded (Baden-Wuertteroberg Ministerium fuer
Umwelt. 1989, 1987). The program is voluntary with financial
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incentives. Compensation occurs where restrictions go beyond good
agricultural practice. Additional funds are provided for
converting some or all arable land to unfertilized grass or trees.
As of August 1990, 62 percent of the farmers in the NSAs have
applied to join the scheme (Schnepf, 1989).
Good agricultural practices relate to the amount and timing of
application of organic and chemical fertilizer, storage of manure,
tillage practices, consideration of nitrogen content of green
manure, maintaining a cover crop, and record-keeping. Farmers have
to comply with limits on fertilizer application so as to be at or
below the economic optimum levels.
West Germany For the area-wide scale protection of ground and
surface waters, the federal government has developed, and will soon
issue, a regulation to control the use of both organic and
inorganic fertilizer. It will govern how much can be applied to
what crops when and where, treatment of green manure, and breaking
of new land. It will also stipulate best management practices and
record-keeping for both inorganic and organic fertilizers (Manale,
1991).
Lander (German provinces) are encouraged to develop wellhead
protection areas (WHPA) to protect drinking water quality. Each
Land may have a different program for controlling the activities
within a WHPA. Lander governments have the authority to pay
farmers or to buy filter strips along key surface water systems to
reduce ecological impacts (Manale, 1991). In the Hessen, for
example, there is a law requiring five meter filter strips along
all major waters.
In Baden-Wurttemberg, which covers an area of karst geology,
farmers with operations located within WHPAs are paid to adopt
agricultural practices that minimize the risk of leaching
(Schrifenreihedes Ministers fuer Umwelt. Raumordnumg,und
Landwirtsch.flft des Landes Nordrhein-Westfalen. 1989). Best
management practices specify maximum amounts of nitrogen that can
be applied given the crop and soil type. These maximum amounts
incorporate a 20 percent reduction in the economic optimum
fertilization rate to account for uncertainties in weather and soil
that affect the likelihood of leaching. In return for
compensation, farmers are required to test their soil twice a year
to prove that the amount of mineral nitrogen remaining in the soil
falls under limits determined by the Land government. There are
also limits on the number of animals that can be kept given the
amount of land to which the manure can be applied. The state is
involved in conducting over a hundred thousand soil tests to
establish a baseline estimate of nitrogen in the soil. The cost of
the program is financed by a Wasserpfenniq—a water penny—that is
born by the water consumers. Responsibility for actually carrying
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out: the paying fanners and monitoring their practices is given to
the municipal water authority. Participation is mandatory
(Schriftenreihe desMinisters fuer Umwelt, Raumordmimg und
Landwirtschaft de Landes Nordrhein-Westfalen. 1986).
In North Rhine Westfalia, the municipal water authority is
required to negotiate with farmers to reduce agricultural chemical
use (Niedersaechsisches Gesetz und Verordnungsblatt. 1990). In
many cases, the municipal water authority has bought farmland to
meet this requirement and then leased it back to the farmer
stipulating management practices. The Land helps facilitate the
agreements and has also helped in the development of markets for
manure (Hanale, 1990). In areas outside of WHPAs, the Land
government has issued regulations governing the application of
manure on agricultural land (Manale, 1991).
In Lower Saxony, limits on the number of animals or kilograms
of nitrogen per hectare per year have been imposed, along with
restrictions on timing and application of manure and a ban on
application after harvest (French Ministry of Agriculture, 1988).
Authorities also encourage nitrogen soil testing but it is not
being used as a tool for assuring compliance (Lida van der Kley and
Graham Bennett, 1988).
France Until recently the programs have been almost entirely
educational. The major exception is a restriction on the size of
livestock operations in water catchment areas. The aim has been to
provide farmers with better information with regard to the input
needs and the environmental consequences of agricultural practices.
Nitrogen soil testing has been promoted as a key pollution
prevention tool. Local authorities, for example, have provided on-
site analyses of mineral nitrogen content of soils. Provincial
governments have established a program of wellhead protection based
upon pathogen travel time. Compliance within these zones, with the
possible exception of livestock operations, has been voluntary.
The Netherlands Three main laws relate to agricultural activity
and ground and surface water protection (Willems, 1987). The
first, passed in 1984, restricted the expansion of the number of
pigs. The second, the Soil Protection Act puts limits on how much
manure can be applied to land, given the soil type, establishes
criteria for identifying areas where the soil has been contaminated
with excessive levels of phosphates from manure and upon which
fertilizer can no longer be applied, requires regions to draw up
ground water protection plans, and establishes wellhead protection
areas. The third, the Fertilizer Act, imposes a levy on animal
waste above a certain stocking ratio—measured in terms of
phosphate per hectare per year.
A parallel effort of the Ministry of Agriculture are pilot
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projects to determine the economic feasibility of treating manure
such that it can be eliminated (Willems, 1987). There are also
pilot projects in recordkeeping and chemical mass balance, in which
farmers are taught to calculate the chemical inputs for farm
operations and the percentages of these chemicals in the outputs,
to estimate the fate of what is not accounted for, and how to
minimize these undesirable residuals (Manale, 1991).
For area-wide protection, the general protection plan is to
phase in reductions in manure applied to soil (as measured in
phosphate) will be phased in by the year 2000. The official
estimate is that there will be a three to five million tons excess
of manure by 1992, not including the excess resulting from the
impending ban on manure that can be applied to phosphate
contaminated soils (European Community, 1989).
The well head protection program is much like that of Baden
Wurttemberg, requiring certain agricultural practices in exchange
for compensation. Protection zones constitute about 4.5 percent
of total area of Netherlands. Fanners in WHPAs are compensated
for the adoption of manure regulations that exceed the general
protection plan according to rates agreed upon by the Farm Union
and the Ministry of Agriculture. Depending upon the province,
either municipal water purveyors are responsible for compensating
farmers and for increasing consumer water rates to cover the
increased costs or a provincial levy is imposed. This occurs only
when provincial authorities apply more stringent rules to the use
of nitrogen fertilizers (Manale, 1991).
Septic Systems
Septic systems do not function as a pollution prevention
practice for nitrogen since they have traditionally not been
designed to remove nitrogen from the effluent. Appropriate siting
and spacing of systems through land use planning, to dilute the
nitrogen in the effluent, may be the only practical approach
currently available to protect drinking water.
The septic tank converts organic nitrogen to ammonium which is
in turn converted fairly rapidly to nitrate in the soil. The only
practical way to remove nitrate from the soil is through the
denitrification process. Denitrification occurs under anaerobic
conditions when an adequate carbon source is available to provide
energy for the bacteria. Because of the aerobic conditions in the
unsaturated zone, appreciable amounts of denitrification do not
occur in most traditional septic systems.
Many different researchers have been trying to develop
engineering methods to increase the denitrification potential of
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septic systems by providing both an aerobic environment for the
nitrification of the ammonium to nitrate and anaerobic environment
to encourage denitrification of nitrate to nitrogen gas. A source
of carbon is added in some designs. Removal of total nitrogen can
reach between 70 and 95 percent in these innovative systems
(Cochet, 1989). However, they are generally not considered
practical for widespread commercial application because of the
expense of installation or operation and maintenance problems
associated with the system design (Rock, 1990).
It is possible to augment the natural vegetation and plant
additional trees or nitrogen demanding crops above septic fields to
take up some ammonium or nitrate and therefore reduce ground-water
contamination. Natural vegetation on the site will have little or
no impact on the amount of nitrate taken up. The results vary
greatly depending on the plant species and the distance from the
field (Ehrenfield, 1987).
In the absence of engineering or technical solutions to
nitrogen removal from septic system effluent, the only practical
option for local communities and states to protect water quality,
where sewers are not economically feasible, is to set minimum lot
sizes to allow for the dilution of the nitrate in the ground water.
10 states have set minimum lot sizes ranging from .23 acres in
Montana to 1.84 acres on lake front property in Minnesota (Yates,
1985).
Minimum lot sizes are also established by localities, although
it is very difficult to make the determination of appropriate lot
sizes based on water quality considerations. The Cape Cod,
Massachusetts town of Pembroke has established a minimum lot size
of one acre. Its goal is to limit the downgradient nitrate level
to 5 mg/L.
Nelson (1988) developed a model to predict the minimum lot
size needed to meet the 5 mg/L standard. He broke sites into four
basic classifications (soil type, slope, etc.) and compared them to
the occupancy rate. The lot sizes needed to meet the standard
varied from .08 acres with 2 person occupancy and a very favorable
recharge environment to 5.9 acres for ten person occupancy and an
unfavorable environment. The biggest variable in determining lot
size was the occupancy rate. Since local governments cannot
realistically limit occupancy of a residence, Nelson recommended
that planners be conservative and assume two people occupy each
bedroom.
The Waquoit Bay Land-Margin Ecosystem Project, through EPA,
National Science Foundation, and National Oceanic and Atmospheric
Administration funding, is developing a computer-based tool and
handbook for local authorities' use to predict impacts on water
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quality based on land use decisions. This four year project is
critically important for increasing local awareness of the
interconnection between land use and water quality and to give
local officials practical tools to make reasoned judgments.
Historically, states and localities have based set back
distance regulations based on structural engineering considerations
rather than water quality concerns. Of the 38 states that have set
back requirements, 21 set the minimum at 100 feet (Kreissl, 1989).
Host of the other state had 50 foot requirements. Ford (1980)
determined in a statistical analysis of well water data in a
Colorado study that a distance of 100 feet had a probability of
nitrate contamination of 21.8 percent and a 200 foot set back had
a probability of nitrate contamination at 9.4 percent. At 200
feet, the minimum lot size would be two acres.
Replacing agriculture with unsewered development will not
markedly reduce nitrate leaching to ground water (Gold, 1990).
According to Gold's model, half-acre zoning with a three person
occupancy rate will make over 42 pounds of nitrogen available per
acre per year. That amount is similar to available nitrogen from
chemically fertilized corn with a rye cover crop.
Regulation
Septage The septage that is pumped out of septic tanks is
regulated by EPA under §405(d) of the Clean Water Act. Septage is
generally pumped by small businesses with several trucks that have
a capacity of about 2000 gallons. Each truck can usually service
two septic tanks. In February 1989, EPA proposed a rule under 40
CFR Part 503 to regulate septage in the same manner as municipal
wastewater sewage sludge (54 FR 5796-5807). The rule required
septage to be analyzed for pollutants covered by the regulations
and land application rates determined by the maximum pollutant
concentration. As a result of the comments received, EPA revised
its proposal in November 1990. The revision proposes to use
hydraulic loading rates of 30,000 gallons per acre per year
(approximately 175 Ibs. N/acre/year) (55 FR 47241). EPA has also
proposed a requirement that a nitrogen consuming crop must be grown
when septage is applied to agricultural land, to protect ground and
surface water.
Septic Systems EPA has the authority to regulate septic systems
under the Safe Drinking Water Act Underground Injection Control
Program (Part 144). Septic systems that serve single family homes
and those that are used only for sanitary waste and have the
capacity to serve fewer than 20 people a day are specifically
excluded from regulation (40 CFR 144.7(2)). Septic systems are
currently authorized by rule just like agricultural drainage wells.
However, EPA is currently developing regulations to deal with this
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subclass of wells.
Urban Sewage
Municipal treatment plants have several options to reduce
total nitrogen loadings to the environment. Pollution prevention
for POTWs can be achieved by treating the effluent or utilizing its
nutrient value through land application.
Regulation and Treatment
conventional secondary treatment does not significantly affect
total nitrogen in the effluent. Tertiary treatment must be
installed which can remove 90 to 95 percent of the total nitrogen
(Anton, 1988). Requirements for such additional treatment are
imposed on a plant-by-plant basis as needed to comply with State
water quality standards. An increasing number of POTWs are
required to reduce nutrients (most frequently phosphorus),
especially those discharging into high quality streams, lakes, and
estuaries.
Nitrogen in POTW effluent is generally in the form of ammonia.
About 1,000 of the 15,500 POTWs are currently required to reduce
ammonia in their effluents to very low levels to protect aquatic
life. Most of these plants reduce ammonia levels simply by using
nitrification processes which convert the ammonia to nitrate. Only
49 POTWs are required to reduce total nitrogen levels as a
condition of their NPDES permit. Total nitrogen is often reduced
through enhancing the natural biological denitrification process.
90 to 95 percent of the nitrogen can be removed with this process.
EPA has not adopted control policies for ammonia. 27 states
and territories have adopted numeric standards. Ammonia controls
to meet restrictive water quality standards can be very expensive,
especially where denitrification is required. Costs of ammonia
control depends on many site-specific factors including plant size,
location, receiving water characteristics, season, and effluent
discharge. EPA has estimated that for the 950 POTWs that discharge
into estuaries, annual construction and operating costs would range
from one to two billion dollars over 20 years. (These costs may be
overstated since they do not subtract for POTWs that already have
denitrification in place.) Currently 62 POTWS that discharge into
estuaries have denitrification requirements in their permits.
Land Application of Sewage Sludge
About 2,000 POTWs land apply their wastewater effluent as a
part of treatment or reuse systems. In some cases these systems
are designed to replace other irrigation water and fertilizer
sources, while in other cases these systems are designed to apply
the maximum amount of wastewater effluent to the smallest amount of
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land possible as a part of effluent treatment or disposal systems.
Many of these systems are designed to recharge ground water with
the treated effluent, while others include underdrains or wells for
recovery of the treated effluent for reuse or surface water
discharge (EPA, 1984). When properly sited, designed, constructed
and operated, land application systems offer a reliable,
cost-effective means of treating and in many cases recycling
wastewater effluents in an environmentally acceptable manner and
problems that do occur generally are associated with grossly
overloaded or poorly operated systems.
The treatment of municipal wastewater results not only in
renovated effluent, but also the production of sewage sludge (from
conventional treatment systems) and septage (from septic systems).
According to the National Sewage Sludge Survey, conducted in 1990,
estimated that approximately one-third of the 7.7 million dry tons
per year of sewage sludge produced by POTWs is landfilled or
incinerated, while another third is applied to land in one form or
another (55 FR 47214) . The remaining third was disposed of through
a combination of surface and ocean disposal and marketing. In 1984
EPA issued a formal policy promoting the beneficial use of sewage
sludge for use as an organic soil amendment and fertilizer
supplement when proper treatment and management practices are
followed (EPA, 1984, Policy). A workgroup of federal agencies has
been formed to implement this policy on federal lands.
EPA has proposed revised regulations for land application
rates of sludge. If pollutant concentrations were below a no
adverse effect level, the only restriction placed on application
rates is that the nitrogen requirement of the crop/land not be
exceeded. Records would not have to be maintained (55 FR 47261).
While treated sewage sludge solids typically contain only one
to two percent (ie, 10,000 - 20,000 ppm) total nitrogen, some
sewage sludges produced by POTWs that treat wastes from breweries
and certain other food processors may contain 10% (ie: 100,000 ppm)
or more total nitrogen depending in part upon the type of treatment
it receives. For example, 'Milorganite1 is a heat dried activated
sludge product sold by the Milwaukee, Wisconsin, Metro Sanitary
District with a guaranteed 5 percent nitrogen content, while
Madison's digested liquid 'Metrogro1 sludge product typically
contains about 10.5 percent (ie, 105,000 mg/L) total nitrogen.
Water Conservation
Reduced flows through POTWs from water conservation appear to
have no effect on total nitrogen loadings in properly operating
systems. Evidence from California suggests that overall wastewater
quality leaving a POTW may improve as a result of increased
efficiencies from reduced flows with the plant. But these
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efficiencies do not affect the nitrogen in the effluent.
Industrial Sources
Effluent from industrial sources poses different problems.
The Toxics Release Inventory indicates that in 1987, 76,944 tons of
ammonium nitrate, ammonium sulfate, ammonia, and nitric acid were
discharged directly to water from industrial sources. These
discharges are regulated under the NPDES permitting program.
However, the permits generally are written for ammonia releases or
total Kjeldahl nitrogen (TKN) releases. In Virginia, this means
that dischargers often nitrify the ammonia in the effluent
(Kennedy, 1990).
For the four chemicals cited, 19,342 tons were discharged to
land in 1987, and 123,132 tons were discharged to POTWs.
Food Processing Wastes
Some solid or semi-solid waste from food processing operations
can be used economically within a limited radius as a source of
nitrogen. As the quantity of N supplied by different types of
waste vary significantly (potato peel waste, for instance, is quite
high in nitrogen), farmers should be instructed on how to account
for these wastes in their nutrient planning.
Wastewater from food processing operations may be discharged
directly to water bodies, or may be discharged to a POTW. Food
processors constitute one industry that would be of particular
concern in a control strategy for total nitrogen.
Research should be done on solid food processing wastes as a
source of fertilizer nitrogen. (The National Food Processors
Association has recently completed a study on feed uses of food
processing wastes). Sources that are not viable for feed should be
marketed to farmers for their nutrient value.
Non-Farm Use of Fertilizer
Home and commercial Site Lawns
There are over 50,000 square miles (or 32,000,000 acres) of
residential and commercial lawn in the United States (Consumers
Union, 1990). In suburban areas especially, where home lawns
account for a significant portion of the land area, overuse of
fertilizer on turf is a potential source of nitrate contamination.
As with agricultural uses of fertilizer, in the case of turf
management there is a point of diminishing or negative returns to
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fertilizer usage. The use of too much fertilizer can cause
excessive build-up of thatch, which impedes healthy leaf growth.
It is apparent that homeowners often apply fertilizer in excess of
recommended levels, believing, as one researcher puts it, that
twice as much means grass that looks twice as good (Angle, 1990).
Homeowners should be made aware of the availability of soil
testing. The Cooperative Extension Service will test soil, usually
for under ten dollars according to Consumers Union. However, there
remain many parts of the country for which an adequate nitrogen
test has not been developed.
Homeowners should be educated in BMPs for home lawns. They
should be instructed in areas such as proper timing and amount of
fertilization and irrigation, planting of native species (cool or
warm season grasses), seasonal nutrient needs, proper mowing
heights, and the nutrient benefits of leaving clippings on a lawn.
Turf clippings are potentially a significant source of the nitrogen
needed by turf. Nitrogen from clippings has been observed to be
used by new growth within two weeks of cutting. After three years,
clippings from previous years contributed 78 pounds of N per acre
(Connecticut Agricultural Experiment Station, ).
In suburban areas experiencing nitrate contamination,
information on alternatives to turf lawns could be offered to
homeowners. In an effort to curtail peak water demand, water
suppliers in Marin County, California have offered modest rebates
to homeowners converting from turf to turfless or 'xeriscapic1
lawns. These are landscape designs employing gravel, bonsai, trees
and wood chips, and require little or no fertilization or
irrigation.
Professional lawn care companies are generally required to
receive a state permit. The permitting system may provide a
mechanism for requiring soil tests to be performed on all lawns
treated, and/or requiring that records of soil N levels and
nitrogen applications be maintained.
Irrigation system installation is restricted in some states to
licensed plumbers and irrigators. Many states restrict only the
connection to potable water supply. Others prohibit any phase of
landscape irrigation without a license. This may be a mechanism
through which states or localities can ensure proper irrigation
design for both home and commercial lawns as well as golf courses.
Municipalities should be encouraged to consider nitrogen
impacts on ground water and surface water when drawing up
comprehensive plans and zoning ordinances . Certain land uses
might be disallowed in sensitive areas. Such uses might include
golf courses, home and garden dealers, greenhouses and nurseries,
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sod farms and industrial facilities handling nitrogenous compounds.
Land development review at the local level can play an
important role in protecting both surface and ground water. For
instance, stormwater collection basins, which may pool large
amounts of fertilizer during rain events should perhaps be located
at places where depth to ground water is deepest.
Golf Courses
Golf courses are heavily fertilized to achieve a quality turf.
Pollution prevention practices for recommended for golf courses
include the use of slow release fertilizers and the competent use
of fertigation have been viewed by several researchers (Snyder,
1979; Snyder, 1980; Cohen, 19 ). Fertigation essentially
simulates the controlled-release of nitrogen that is provided by
slow release forms, but offers the advantage of allowing cheaper,
conventional forms of fertilizer to be used (Snyder, 1979).
Fertigation is best managed as frequent, light applications, rather
than infrequent, heavy watering, and is best adapted to courses
that have fully automated irrigation systems, true of many courses
in the South, Southeast, and arid Southwest.
Golf course superintendents should be provided with
information concerning the relative efficiencies and cost
effectiveness of slow release fertilizers and fertigation, compared
to conventional fertilization. The Golf Course Superintendents'
Association of America (GCSSA) is the professional organization
which might best provide this information,
In areas where nitrates are a particular problem,
municipalities or states might require that land use applications
be accompanied by nutrient management plans. Cape Cod, which is
served by a sole source aquifer designated under the SOWA, has
established a nitrate-N planning guideline of 5 mg/L within zones
of contribution to public supply wells (CCPEDC, 1978).
Some golf courses, particularly in California and Florida, and
to some extent in Pennsylvania and perhaps other states, apply
treated wastewater from local sewage treatment plants to the land.
The golf courses benefit from the nutrients in the wastewater. The
nitrogen value of such wastewater should be quantified and made
known to superintendents.
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REMEDIATION AND TREATMENT
Where pollution prevention has not been implemented or has
been ineffective, the possibility of removing nitrate from water
must be explored. As part of the nitrogen cycle, nitrate is
constantly being removed from water naturally through
denitrification. Nitrogen is also taken up by plants from the soil
and in the air. Researchers are exploring ways that the natural
denitrification process can be enhanced where excess nitrate is a
health or ecological concern. Technologies are also available to
remove nitrate physically from drinking water. This section
discusses treatment approaches for water that has been contaminated
with excess nitrate.
Public Water Systems
In order to protect human health for people drinking water
supplied by public water systems, EPA or the states enforce the
regulations written under the Safe Drinking Water Act (SDWA). The
regulations require public water systems to monitor to assure
compliance with the MCL, report the monitoring results to EPA or
the state, and meet all MCLs. States have primary authority to
enforce the SDWA if they adopt regulations at least as stringent as
EPA. Otherwise, EPA retains "primacy" over the enforcement of the
act. EPA has primacy over drinking water programs in
Wyoming, Washington, D.C., and all Indian lands.
In order to protect the public health from the acute health
effects of methemoglobinemia, EPA set the nitrate MCL at 10 mg/L.
New monitoring and public notification regulations were promulgated
December 1990 that reflect the acute nature of this disease.
Monitoring
The first line of defense EPA employs to protect the public
health from the effects of drinking water contaminants is to
require all public water systems to sample their water supplies.
Nitrate and nitrite have more frequent monitoring requirements in
the new regulations than any other inorganic or organic chemical.
Ground water systems will be required to monitor annually. If any
result is 50 percent or more of the MCL (5 mg/L, nitrate; .5 mg/L,
nitrite), monitoring must be conducted quarterly until four
consecutive quarters show results under 50 percent of the MCL.
Surface water systems, because the nitrate/nitrite level varies
more for such systems, must begin monitoring quarterly until four
consecutive quarters show results that are less than 50 percent of
the MCL. Thereafter, annual monitoring is acceptable unless the 50
percent level is surpassed.
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Public Notification
If the nitrate level in any monitoring sample exceeds the MCL,
another sample must be taken within 24 hours or the public must be
notified of the results. The public water system then has two
weeks to resample. Nitrate violations require public notification
as soon as possible, but no later than 72 hours after the
violation. The notice must be given to radio and television
stations in the area. The notice must be repeated every three
months by mail or hand delivery as long as the violation exists.
The public must also be notified of any failure to monitor or the
existence of a variance or exemption every three months.
Public notification regulations contain mandatory language for
nitrate that encourages parents to provide infants under six months
with an alternate source of drinking water.
This notification requirement is primarily designed to protect
the public health. It is also a means of informing the public
about problems with the water supply (Wardlaw and Bruvold, 1989).
Notification may also be a useful tool gather public support for
increased expenditures to correct problems (USGAO, 1982).
Treatment Options
The most cost-effective way for a public water system to meet
the MCL is simply to blend the water from a high nitrate source
with low nitrate water. Drilling a deeper well or a well in a
different part of the aquifer may be an option for some systems.
A new well may just be a short term option since the nitrate
contamination of shallow aquifers may simply be a function of time
where the contamination has not had sufficient time to reach the
deeper aquifer.
Three technologies are approved by EPA for physically removing
nitrate from water. If no alternate water source is available,
reverse osmosis (RO), ion exchange (IE), or electrodialysis
reversal (EDR) must be used. RO and EDR both use membranes to
remove nitrate. IE uses anion exchange resins. Removal rates for
the technologies are: RO, 67 to 95%; EDR, 51 to 92%; and IE, 65-
99%. Conversion of nitrite to nitrate through breakpoint
chlorination is an economical method that can be used when nitrite
MCLs are exceeded.
The costs for all three technologies are considered feasible
for a large public water system (serving over 100,000 people). RO
and EDR have comparable costs from $1.50/1,000 gallons for a large
system (about $150 a year per household) to $5.90/1,000 gallons for
a small system. Ion exchange costs range from $ .77/1,000 gallons
for a large system to $3.40/1,000 gallons for a small system.
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A public water system can apply for a variance or exemption
from meeting the MCL. A variance can be granted if the system has
installed an EPA approved technology and it still cannot meet the
HCL and does not pose an unreasonable risk to health. Public water
systems can apply for an exemption if they are unable to meet the
MCL because of compelling factors (including cost), the system was
in operation at the time the MCL was established, and it does not
present an unreasonable risk to health. States can renew an
exemption for smaller public water systems with 500 or fewer
connections for additional two year periods for financial reasons.
15 public water systems have variances or exemptions for the
nitrate MCL (Wade Miller Ass., 1990). The affordability guidance
EPA is proposing suggests that households should not have to pay
more than $650 per year for drinking water or over two percent of
the median household income.
The draft Regulatory Impact Analysis of the proposed drinking
water regulations (1989) estimates that public water systems will
have to spend $192 million annually over the next 20 years to meet
the nitrate MCL. Small public water systems account for $129
million of those costs. The costs do not take into account
blending water, drilling a new well, or using breakpoint
chlorination instead of using an approved technology.
New Nitrate Removal Technologies
Currently approved nitrate removal processes have several
disadvantages that new technologies are trying to avoid. RO, IE,
and EDR produce a significant amount of effluent that must be
disposed of and not reintroduced into the water supply. These
processes are also very expensive, especially for small systems.
In order to avoid waste disposal costs associated with ion
exchange and reverse osmosis, researchers are now experimenting
with enhancing the natural biological denitrification process to
treat drinking water. Although this technology is new to drinking
water treatment, it has been used for nitrogen removal from some
wastewater treatment plants for years. As part of the nitrogen
cycle, bacteria in the soil consume nitrate and convert it to
nitrogen gases. The rate of natural denitrification often does not
remove enough nitrate from the water to allow its use for drinking
water when anthropogenic additions have been made to ground and
surface waters.
Three pilot projects have been operating in Belgium to
experiment with materials to enhance the growth of denitrifying
bacteria to remove nitrate from a surface water reservoir
(Liessens, et al. 1990). The projects differ in term of the
material on which bacteria are grown (sand or polyurethane) and the
bacteria's food source (methanol or hydrogen). Liessens, et al.
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concluded that the fluidized bed reactor (sand and methanol) was an
appropriate denitrification technique at low temperatures, but more
evaluation of all techniques was needed. France also has several
biological denitrification plants operating. Since this technology
is still considered experimental, EPA has not recognized it as an
approved removal technology.
Enforcement
When an MCL is violated, the primacy agency, EPA or the state,
begins an enforcement action against the public water system. The
actions range from informal actions such as a notification of the
violation to the filing of a criminal or civil case against the
PWS. An informal request for public notification is the most
frequent action taken against public water systems violating the
nitrate MCL. According to FRDS data compiled for this report,
between October 1987 and April 1990, out of 280 systems in
violation, 20 administrative/compliance orders were issued and no
fines were imposed or criminal/civil cases filed. Compliance with
the MCL was achieved in 30 cases. Since about 92 percent of the
violations identified through FRDS were from small public water
systems, informal actions and technical assistance are considered
more appropriate to bring the systems back into compliance with the
MCL.
EPA is currently developing a plan to increase enforcement
against the worst violators. Public water systems are considered
in "significant noncompliance" if MCLs are violated in repeated
monitoring periods. Primacy agencies then have six months to take
appropriate action. Appropriate action is defined as a bilateral
contract between the state and the pubic water systems, a state
Administrative Order, a Federal Administrative Order, or a
referral for a civil or a criminal case. This increased
enforcement is designed to make violators assure that water
supplied to customers meets federal standards either by treating
the water supply, changing raw water sources, or combining with a
public water supply that meets the MCLs.
The General Accounting Office's (1990) assessment of the
implementation of the Safe Drinking Water Act concluded that
enforcement actions by the states were not timely, appropriate, or
effective in returning PWSs to compliance. Many significant
violations had persisted for years. GAO cited costs, especially
for small systems, and technical barriers such as no available
alternative water sources as the principal hindrances to
implementation.
The Office of Drinking Water at EPA has begun a new program,
called Mobilization primarily to aid small public water systems in
meeting the requirements of the SDWA through institutional,
technical, and training support. States, public health officials,
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and the general public are also being targeted through this
program. Public water systems need support from all these sectors
to raise awareness of the importance and costs of having safe
drinking water. Mobilization activities such as developing low-
cost treatment technology might help small public water systems
meet the nitrate MCL.
Domestic Drinking Water Supplies
EPA has no authority over drinking water wells that serve
fewer than 25 people or 15 connections. States generally do not
regulate water quality in private wells either, with a few
exceptions. Washington requires any well with two or more
connections to meet bacteria and inorganic chemical standards.
Idaho requires any well with at least 10 connections to meet all
primary drinking water standards. New Jersey mandates that all new
private wells must test for bacteria, nitrate and meet all the
primary drinking water standards, except for pesticides.
Private wells are generally at greater risk of contamination
than public wells for three reasons. First, since the cost of
drilling a well is based on a per foot charge, many homeowners
drill only into the shallow aquifer and do not tap the more
protected deeper aquifers generally used by public water systems.
Second, private wells are more often located close to potential
sources of contamination, such as septic systems. States variously
recommend that private wells be located a minimum of 50 to 100 feet
upgradient from a potential source of contamination such as a
septic system. Finally, the construction material and method of
older wells allow nitrate (and other contaminants) to enter the
wells more easily.
Several monitoring studies have tried to correlate the
characteristics of wells with the extent of contamination. The
risk factors include age, depth, method of construction (dug,
drilled, driven), soil textural class, and distance to potential
source of contamination. One Kansas study found that wells more
than 70 years old, within 100 feet of a potential contamination
source, and 21 to 99 feet deep in silty or clay soil are most
likely to have nitrate levels that exceed 10 mg/L or 20 mg/L
(Koelliker, et al. 1988). The Iowa State-Wide Rural Weil-Water
Survey (1989) found that 35.1% of the wells less than 50 feet deep
were contaminated with nitrate compared to 12.8 percent of the
deeper wells. Hallberg (1989) believes that this phenomenon may be
just a function of time and nitrate will eventually reach the lower
aquifers.
Most states have no formal program for testing private well
water. Private wells are usually tested by states only as part of
a special study or when a specific problem is reported. Almost
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half the states will test for bacteria either free or for a fee
when a request is made. Nitrate is the second most commonly tested
substance.
Almost all states will provide a well owner with a list of
labs certified to conduct testing for various contaminants. Local
and state health departments often are willing to recommend
specific tests, interpret results, and offer advice on how to
correct problems. If a doctor or public health official requests
a water sample, that state will usually conduct the test for the
contaminant(s) indicated. A spill or a leaking underground storage
tank will usually involve the state, especially if enough
complaints are heard at the state level or there is publicity.
Many states concede that they respond more thoroughly the harder
and longer a well owner complains.
Banks often require a test of the well water before they will
grant a mortgage. One sample to test for bacteria is usually the
only requirement, although nitrate test requirements are becoming
more common. Generally the information on water quality is only
given to the well owner, although in Nebraska, the state performs
the tests for a fee and keeps the information to help gauge the
existence or severity of a problem. Other states distrust these
data because of the ease of drawing a potable water sample at some
time of the year. In one study in Ohio, nitrate levels in some
wells were shown to fluctuate as much as 30 mg/L during the course
of a year. Four states mandate testing for bacteria and nitrate
when property changes hands (Baker, 1990).
Many states try to influence the water quality of private
wells by regulating the construction of new wells or the upgrade of
existing wells. States require placement of new wells outside a
zone of contamination and at some minimum depth (usually 10 to 30
feet). Construction with certain casing material and grouting mix
specifications are also common requirements. Some states regulate
well drillers through licensing or registration procedures. Eleven
states use all or part of a test developed by the American Well
Water Association. Many officials believe that the enforcement of
these regulations is virtually non-existent. Washington, for
example, has required well logs since 1971, but enforcement is just
beginning. The extent of the compliance with the regulation is
unknown.
Local health officials are often more involved than their
state counterparts since they are closest to the well owners, but
most programs seem to be extremely limited because of a lack of
funds. States do not often mandate specific programs for private
well testing to the counties.
Some states, like New Mexico, have developed innovative
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programs for dealing with private wells. In addition to responding
to complaints, a water testing laboratory is sent to areas all over
the state to test anyone's water free of charge. These "water
fairs" are often held in conjunction with county fairs or at other
public locations. Many problems have been uncovered including some
that affect public water systems. 65 percent of the samples in one
area violated the nitrate MCL. The legislature passed emergency
legislation to fund a public water system for the area.
Other states, especially in the Midwest, have passed ground
water protection legislation or instituted ground water strategies
in the past few years. These initiatives usually fund some kind of
monitoring program or special studies to determine where there are
currently problems or where problems are likely to occur. The end
result of these processes would probably be the creation of
districts where certain best management practices would be
implemented.
Private Treatment Options
Private well owners with high nitrate levels can choose among
several options, depending on the cost of the options, the level
and type of contamination, and the amount of water the well owner
wants to be potable. They can continue drinking high nitrate
water, use bottled water, drill new or deeper wells, or install
treatment devices to remove nitrate. New or deeper wells may only
be a temporary solution because nitrate levels in deeper aquifers
many increase with time.
All water supplied by public water systems have to be potable
even though less than 10 percent is used for drinking or cooking.
If water in a private well is high in nitrate, it cannot simply be
boiled. Boiling does not remove nitrate, but concentrates it
instead thereby making the water more hazardous.
If high nitrate levels are the result of the location near a
source of contamination and faulty construction of the existing
well, a new or deeper well can be drilled. Over 400,000 new
domestic wells are drilled annually. Average costs for a new well
and a pump are $3,500 to $4,000 (McCray, 1986). If the aquifer
itself is high in nitrate from diffuse sources, the nitrate must be
removed. Nitrate can be removed from drinking water by some of the
same methods used by public water systems: reverse osmosis or ion
exchange. Distillation is also an option for homeowners. Costs
range from $500 to $1,000 to equip a house (point of entry) or a
single tap (point of use) with the treatment equipment. There is
also an additional annual maintenance charge of approximately $100.
Maintenance is a very important component of the treatment. When
the membrane is clogged, as much as 60 mg/L can be dumped into the
water.
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Reverse osmosis and distillation are only suitable for
drinking and cooking water. Depending on the treatment unit 75 to
90 percent of the water will go down the drain without passing
through the membrane. It usually takes between three and six hours
to produce one gallon of drinking water. Distillation averages
five hours per gallon (Consumer Reports, 1990).
Bottled Water
Bottled water is often considered an option to avoid
contamination problems perceived to be associated with public water
supplies and private well contamination. It is important to
understand to what extent bottled water should be considered an
alternative.
All bottled water that is sold interstate or imported is
regulated by the Food and Drug Administration (FDA). Bottled water
must meet all MCLs. Bottlers are required by FDA to sample and
analyze their water supplies for contaminants at least once a year.
They must keep maintenance and testing records for inspection. FDA
has a random testing program, but generally random tests are
performed only if FDA has a reason to suspect a violation of the
regulations.
Most bottled water is sold interstate. However, when it is
exclusively sold intrastate, the state has regulatory authority.
Often state regulations are stricter than FDA, requiring, for
example, increased monitoring and quarterly inspection of testing
records.
Under the Fair Packaging and Labeling Act, bottlers are
required to label any water that does not meet MCLs "substandard
quality". For nitrate, water is substandard if the level is over
the MCL, but less than 40 mg/L. If the nitrate level is greater,
water must be labeled "adulterated" and potential etiological
effects must be included on the label. FDA has no authority to
seize any adulterated water. It may only require truthful labels
or use negative publicity against bottlers.
In 1987, Consumer Reports tested 50 brands of bottled water
for various contaminants including nitrates. None of the brands
violated the MCL for nitrates although arsenic, fluoride,
trihalomethanes, and tetrachloroethylene levels were violated in
some samples.
It appears from the Consumer Reports testing that bottled
water is generally safe, at least from a nitrate perspective.
Therefore anyone who has nitrate in their water supply over 10 mg/L
should feel fairly comfortable in giving their infant bottled water
in place of the tap water. However, the FDA testing program and
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authority over penalties for violations by bottlers of the MCLs
need to be strengthened.
US Department of Agriculture
Since 1942, the Farmers1 Hone Administration (FmHA) has been
making loans or giving grants to small (population under 10,000)
community drinking water and waste water systems that are unable to
get credit from any other source. Priority is given to systems
that do not meet SDWA requirements. Individual states operate the
program with financing and guidance from FmHA. States establish
the priorities based on factors such as per capita income and size.
The system must meet all requirements under the SDWA and CWA when
completed. FmHA prefers to give loans to systems that do not rely
on individual point of entry/point of use treatment for each
household. They do not have confidence that the required
maintenance will be performed.
FmHA has applications for approximately two or three times the
$400 million available for loans and grants this fiscal year.
There is currently about $7 billion in its portfolio. A guaranteed
loan program has just begun with $50 million capitalization,
although there does not seem to be a market for these loans yet.
FmHA also operates a Circuit Rider program to help system
operators with operation and maintenance. Through a contract, the
National Rural Water Association provides coverage for the lower 48
states with an average of one circuit rider per state. The circuit
rider is available to help anyone who asks whether they are a
borrower or not. The program will also send operators to training.
Individual housing loans are made in areas with population up to
20,000. FmHA requires that houses with domestic wells and on
public water systems meet nitrate levels in order to qualify for
the loan. Because of the problem with some communities violating
MCLs, FmHA will make exceptions and allow POU/POE treatment (not
for private wells). They prefer the units to be centrally owned
and operated by the PWS. In any case the operator has to show the
ability to properly operate and maintain the system (including
financial).
Aquifer Remediation
EPA's laboratory in Ada, Oklahoma has begun laboratory
experiments on the in situ restoration of an aquifer contaminated
with nitrate. The emphasis has been on injecting a source of
carbon into a nitrate plume in a model sand tank in the laboratory.
In an aquifer the carbon source must be spread naturally.
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INSTITUTIONAL ISSUES IN IMPLEMENTING THE NITROGEN ACTION PLAN
Agencies at the Federal, State, regional, and local levels of
government have specific roles and responsibilities for addressing
water quality problems associated with nitrogenous compounds (NCs).
These agencies vary greatly in institutional capability—in the
legal authority and technical and financial resources available to
them to protect ground and surface waters from contamination by
nitrogen compounds.
The following discussion outlines in broad terms three major
institutional issues for all levels of government with regard to
the implementation of water quality programs that address
contamination from nitrogen compounds: 1) current roles and
responsibilities, 2) existing authorities and examples of
programs, and 3) technical and financial resources currently
available.
Federal Government
Federal authorities often provide the basis for local and
state decision making by establishing requirements or goals that
must be met by state and local authorities. Land use controls have
not been mandated by federal statute, per se, but federal programs
can promote the establishment of state and local controls by
providing cooperative funding and by withholding or placing
conditions on federal grants. In addition, some federal statutes
provide legal authority for the federal government to preempt state
and local authorities to achieve regulatory standards. Often the
federal influence on land use is necessary to provide the basis for
balancing competing economic and environmental interests at the
local level.
The primary federal agencies that would play a major role in
supporting and implementing the Nitrogen Action Plan are the U.S.
Environmental Protection Agency (EPA), the U.S. Department of
Agriculture (USDA), and the U.S. Geological Survey (USGS).
Environmental Protection Agency
Roles and Responsibilities
EPA is the principal Federal agency charged with protecting
the nation's water resources from pollution. It has both
regulatory and non-regulatory responsibilities that directly or
indirectly address NC contamination of water. Under its regulatory
role, EPA limits discharges from point sources of NCs by issuing
permits and sets and enforces drinking water standards—or
delegates these responsibilities to states that have demonstrated
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the capacity to carry them out. Alternatively, instead of
regulating specific sources of contamination, the Agency has
established programs that require states to protect surface and
ground waters from many or all major anthropogenic sources (e.g.,
Nonpoint Source and Wellhead Protection Programs).
EPA's non-regulatory role is generally directed at building
state and local capacity to address contamination of water through
public education, technical and financial assistance. At present,
these broad-based efforts have not focused on protecting water from
NC contamination but have the potential to do so.
Authorities and Programs
EPA derives most of its authority to address water quality
problems associated with NCs from three statutes: the Safe Drinking
Water Act (SDWA), the Clean Water Act (CWA), and the Toxic
Substances Control Act (TSCA). The Agency is already taking action
under SDWA and the CWA, and is investigating the potential use of
TSCA and CZMA to address currently un-regulated sources of NCs,
such as fertilizers. Both SDWA and the CWA are scheduled for
reauthorization by Congress in 1992.
Four programs under SDWA can deal nitrogen compounds and water
quality. Nitrate and nitrite drinking water standards for public
water systems are set and ultimately enforced by EPA. In addition,
the 1986 Amendments to SDWA require each State to develop a
Wellhead Protection (WHP) Program [§ 1428] to protect ground water
that supplies public drinking water wells from sources of
contamination. Because of the highly site-specific nature of
ground water, adequate protection of public wells usually requires
active participation of local governments in controlling a variety
of potential contaminants. Land use controls are an important
local tool for wellhead protection. Sole-source aquifer program [§
1424] prohibits federal assistance to projects that adversely
impact sole source aquifers. Section 1424 may, though, assist
projects that eliminate contamination over sole source aquifers.
While no activities are prohibited under the federal program, State
and local government may use the Sole Source designation as
justification for land use controls, as was done to protect the
Cape Cod public water well fields. The Underground Injection
Control program regulates injection of fluids into underground
sources of drinking water. Agricultural drainage wells, large
septic systems, and wastewater disposal into ground water will be
regulated under Class V regulations of this program.
Under CWA authorities, EPA or the state primacy agency issues
permits to point sources of pollution that limits the contaminants
in the effluent discharged into surface waters. Industries,
wastewater treatment plants, and feedlots are all permitted to some
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degree under this program. For example, construction seed money
increases the availability of centralized waste water treatment.
Coupled with comprehensive plans for phased implementation, seed
money advances development along infrastructure emplacement lines
and reduces the number of scattered developments whose reliance on
septic systems contaminating groundwater and surface water. Also,
the CWA requires States to address surface water pollution through
the nonpoint source state management programs [§ 319]. Nonpoint
source pollution includes runoff of nitrogen compounds into surface
waters from such major sources as fertilizer and manure from
cropland and pastures. The control of nonpoint source pollution
invariably includes the establishment of best management practices
(usually voluntary) or the establishment of regulatory controls,
such as permits placing conditions on land use practices.
The Clean Lakes Program [§ 314], National Estuary Program [§
320], and the Great Lakes Program [§ 118] all provide money to fund
the development of management programs for specific water bodies.
State revolving funds [§ 601] provide seed money to states to
establish a fund to make loans to waste water treatment plants.
Recognizing the value of estuaries, the National Estuaries
Program was established under the Clean Water Act [§ 320] to
coordinate existing regulatory, financial, and institutional
resources to deal with problems of specific estuaries of national
concern through the development of Comprehensive Conservation and
Management Plans. Originally Puget Sound, San Francisco Bay,
Albemarle-Pamlico Sound, Long Island Sound, Narragansett Bay, and
Buzzards Bay were included in the program. Now Santa Monica Bay,
Galveston Bay, Sarasota Bay, New York/New Jersey Harbor, and
Delaware Bays have been added.
T8CA has been used so far in connection with one source of
NCs. The use of nitrites was banned as an additive to certain
metal working solutions because of nitrosamine formation. EPA is
investigating other options for using TSCA to control NCs including
regulation of fertilizer use and fertilizer dealerships and a
variety of projects based on geographically specific risk reduction
activities. If stringent requirements were promulgated,
geographically based targeting could change regional production
cost differentials and, ultimately, affect the location of certain
economic activities and associated land uses. Regulation of
fertilizer manufacturers may also be considered under the proposed
Product Stewardship Rule. Health effects can be investigated under
a test rule.
The CZMA was amended at the end of 1990 to include significant
new programs which can be used to control contamination from NCs
by including minimum requirements for NC evaluation and control in
the guidance. The amendments establish a new Coastal Nonpoint
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Pollution Control program which require states with an approved
coastal zone management programs to develop a new program to deal
with nonpoint sources. EPA and the National Oceanic and
Atmospheric Administration (NOAA) are responsible for developing
guidance and approving state programs which must include
enforceable policies and mechanisms. These programs must be
coordinated with existing water quality programs, including §319
programs. If states fail to develop approvable programs, NOAA and
EPA are required to with hold grant funds beginning in fiscal year
1996 (10%-FY96; 15%-FY97; 20%-FY98? 30%-FY99+).
Technical and Financial Resources
EPA's nitrates-related technical assistance efforts include
the development of vulnerability risk factors for nitrates, the
development of guidance for septic tank management, and soil-test
technology transfer in Pennsylvania and Iowa, all underway, and
research on the economic efficiency of fertilizer application for
its potential to reduce application rates (planned). Also, EPA's
on-going study of ground water/surface water interactions may
enable States to estimate loadings of NCs from ground-water
discharge to stream segments.
Financial assistance generally consists of grants to States
for building their institutional capacity to protect ground and
surface waters or to support projects that address contamination
from specific sources. The CWA, for instance, authorizes grants to
States for the development of comprehensive ground-water protection
strategies as well as for projects that propose to manage nonpoint
sources [§ 319]. At least 15 state project proposals to EPA for
§319 funding address NCs.
U.S. Department of Agriculture
Roles and Responsibilities
USDA has recently added water quality protection to its
traditional responsibilities. USDA's new Policy for Water Quality
Protection (1990) states that the Department will "foster
agricultural and forestry practices that protect and enhance the
Nation's ground and surface water resources" through research,
education, technical assistance and technology transfer, cost-share
assistance, and farm management guidance. USDA has several
agencies that have been assigned responsibilities for water quality
protection, the Soil Conservation Service (SCS), the Extension
Service (ES), and the Agricultural Research Service (ARS).
Authorities and Programs
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Under the President's Water Quality Initiative, USDA is
funding demonstration projects designed to develop, improve, and
disseminate best management practices (BMPs)—some of which will
demonstrate better management of fertilizer and manure use—and to
reduce NC contamination of ground water through more efficient use
of N fertilizer. USDA also has the authority to address water
quality protection through a national plan for soil and water
conservation required under the Resources Conservation Act of 1977.
The new Farm Bill or the Food, Agriculture, Conservation, and
Trade Act of 1990 contains four programs that may affect USDA's
ability to deal with nitrate contamination. The Conservation
Reserve Program (CRP) directs an enrollment of six million new
acres of environmentally sensitive lands. The Wetlands Reserve
Program will enroll up to one million acres of wetlands into 30
year or permanent easements out of the total CRP acreage. Under
the Water Quality Incentives Program SCS will contract with farmers
to provide incentive payments (up to $3,500 per year, per farm for
up to five years) for adoption of BMPs to protect water quality.
The Environmental Easement Program provides for permanent easements
on lands which pose a significant environmental threat. The exact
eligibility for these lands has not yet been determined, nor is any
funding available.
Technical and Financial Resources
USDA is conducting research on NC contamination pathways in
the soil and on farming methods to reduce or prevent contamination.
The SCS and ES, in particular, will conduct demonstration projects
and provide technical assistance to show farmers the benefits of
the new practices and how to implement them. USDA also collects
state level fertilizer use data.
Financial assistance to farmers is available through cost-
share payments for the implementation of BMPs—including fertilizer
and animal waste management practices—through funding of
demonstration, hydrologic, and other water quality projects under
the Water Quality Initiative. As yet, USDA has not made a
commitment to conduct or fund off-farm monitoring for NCs.
U.S. Geological Survey
Roles and Responsibilities
USGS is a scientific and technical agency without regulatory
responsibilities. It monitors ground and surface water, conducts
water quality assessments, investigates trends in water quality and
the relation of land uses to water quality. It also provides
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information to agencies at all levels of government in support of
water quality protection efforts. In carrying out these
responsibilities, USGS provides support in addressing NC
contamination concerns by helping to determine the location and
extent of NC contamination.
Authorities and Programs
USGS is involved in at least two programs that are helping to
assess the impacts of fertilizer use on water quality. First, in
the pilot phase of its National Water Quality Assessment Program,
the USGS is investigating the extent and location of ground-water
pollution by agrichemicals in several regions of the U.S. Second,
it is conducting research on the impact of growing corn on ground
and surface water under the Midcontinent Research Initiative.
Several other programs, such as the Federal-State Cooperative
Program and the State Water Resources Research Institutes Program,
conduct and support research on water quality, some of which may be
applicable to NC contamination problems.
Since it is not possible with current data to develop a truly
national picture of the quality of ground and surface waters, the
United States Geological Survey (USGS) has initiated a major
national assessment. The National Water-Quality Assessment (NAWQA)
Program is designed to describe the status and trends of U.S.
waters and identify the factors that affect water quality.
Beginning in fiscal year 1991, with a budget of $18 million, USGS
will begin to study the first 20 hydrogeologic units. The first
cycle of investigations of all 60 units is scheduled for completion
in 2002. Costs will increase to about $60 million annually. The
national and regional synthesis of this information will emphasize
nutrients beginning in fiscal year 1992 (Leahy, et al., 1990).
Technical and Financial Resources
One of the major responsibilities of USGS, as mentioned above,
is to provide technical assistance to government agencies and the
public on water quality-related matters. This assistance includes
basic and applied research, mapping and transfer of mapping
technology, information collection and management, and outreach.
USGS is conducting most of these activities in its assessment of
the impact of fertilizer use on water quality under the National
Water Quality Assessment Program.
The Federal-State Cooperative Program provides 50/50 cost-
sharing between USGS and cooperating State or local government
agencies. Program activities include collecting hydrologic data
and water quality investigations. In addition, USGS1 Water
Resources Research Grants Program awards competitive matching
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grants to qualified universities, foundations, private firms,
individuals, and State or local agencies to support research on
water resources problems of national interest.
Tennessee Vallev Authority
STATE GOVERNMENTS
Federal programs rely extensively on State technical capacity
and legal authorities to meet the requirements of mandated
environmental programs. States have the primary responsibility and
expertise for identifying contamination threats, characterizing
threatened resources, establishing enforcement and compliance
programs, and establishing sate priorities consistent with the
requirements of federal Laws.
The States
Roles and Responsibilities
States and localities play perhaps the largest role in water
quality protection. In addition to implementing and enforcing
federal regulatory programs, state and local governments are
developing and implementing EPA's Nonpoint Source (NFS) and
Wellhead Protection (WHP) Programs, State Comprehensive Ground-
Water Protection Programs, and their own water quality programs.
state agencies provide oversight and support (land grant
universities provide support) to local government by enhancing the
technical and staffing capabilities of local government when local
planning agencies seek compliance with mandated environmental
programs. States have primary responsibility to establish
priorities relative to federal mandates, identify and characterize
contamination threats and establish enforcement programs.
Sometimes states enact legislation that delegates specific water
quality program authorities to local governments. All of these
programs have the potential to address sources of NC contamination.
states may establish more stringent regulations than those
promulgated by EPA, or place greater emphasis on a non-regulatory
approach through research, monitoring, and technical assistance to
farmers and local officials. A common objective is to develop an
approach that mixes regulatory and non-regulatory elements in the
most effective manner.
Many state agencies have water protection responsibilities.
Three types of agencies that often play major roles in protecting
water from agrichemical contamination are state departments of
environmental protection or natural resources, agriculture, and
public health. Coordination of the water protection activities of
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different agencies is essential to avoid conflicts between agencies
with different perspectives and duplication of effort. For this
reason, many states assign a lead role to a single agency or
establish coordinating committees to facilitate communication among
agencies.
Authorities and Programs
States derive authority to address sources of NC contamination
from such federal laws as the SDWA and the CWA. These laws allow
states with adequate institutional capacity to enforce federal
regulations and standards or establish programs (e.g., WHP, NFS)
that provide technical and/or financial assistance to states to
develop their own approaches to protecting their ground and surface
waters. Some states have passed their own statutes and developed
regulations or programs that support or go beyond the Federal
programs. A few examples of state programs that address sources of
NCs are:
Iowa's tax on fertilizer purchases funds monitoring and soil
testing programs.
• Nebraska has recently required the Central Platte Natural
Resources District to adopt a ground water quality management
plan. The plan includes regulatory requirements for
addressing NCs, with possible bans on fall and winter
fertilizer applications, training on use of fertilizers, and
mandatory recordkeeping.
* Arizona has a cost-share program for implementation of
approved BMPs and alternative agricultural practices.
South Dakota's Centennial Environment Protection Act of 1989
focuses on the development of alternative agricultural
practices and management of nonpoint sources. The State's
Groundwater Protection Fund should yield $500,000 annually and
will support grants for ground water research and public
education.
Minnesota's Ground Water Protection Act of 1989 authorizes a
new fund to enable the State to respond to agrichemical spills
and other pesticide and fertilizer incidents. Surcharges on
fertilizer tonnage and agrichemical businesses will feed the
fund. Also, the law authorizes programs to reduce the use of
fertilizers.
Wisconsin has established cost-share programs to construct
manure storage facilities and to implement approved BMPs and
alternative agricultural practices. The "Bad Actors" law
permits the State to treat individual farmers not co-operating
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in a regional water quality program as a "point source" to
force compliance.
• Florida has delineated Water Control Districts to regulate
both water supply and quantity.
Technical and Financial Resources
State agencies (and universities) provide much of the
technical capacity to meet the requirements of Federally-mandated
environmental programs as well as their own programs. States also
provide technical support to local water quality protection
efforts. Examples of the types of technical assistance that States
(often in collaboration with Federal and local agencies and
universities) provide that currently or potentially address NCs
include: preparing technical documents on approved BMPs and septic
tank installation and management, preparing guidance on land-use
controls, mapping sources of contamination and aquifers, developing
geographic information systems, delineating wellhead protection
areas, conducting monitoring and water quality assessments, and
improving soil tests.
States receive financial assistance from Federal programs
(NFS, POTW construction grants, CWA grants for ground water
protection strategies, etc.) and many have established their own
sources of funding. Some of the Federal grants must be used for
specific purposes, while others are partially or entirely
discretionary. Up to 20 percent of CWA POTW Construction Grant
funds, for instance, may be used for NFS control. California has
opted to take advantage of this provision to make $13.42 million
available for FY 1990, and will use some of these funds to protect
bays and estuaries from nonpoint sources, including sources of NCs.
State sources of funding other than State legislative
appropriations include fertilizer sales taxes (Iowa, Kansas),
ground water protection funds, water utility user fees, impact fees
(septic tanks, Florida), and permit fees (large feedlots), real
estate transfer tax (MA), License fee (10), Sales tax (WA),
Stormwater utility fee (regional government), Environmental trusts
(MN).
Regional or Cross-Jurisdictional Efforts
Roles and Responsibilities
Numerous regional entities across the U.S. have
responsibilities for water quality protection. These include both
in-State and supra-State cooperative programs and administrative
bodies. The basic role of regional entities is to address water
quality problems that cannot be dealt with at any single level of
government because they span more than one local or State political
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or administrative jurisdiction.
Authorities and Programs
Cross-State programs generally derive authority from
agreements or charters signed by governors (or their
representatives) of the participating States. The agreements
describe and assign the responsibilities of the participants, and
include at least a commitment to obtain the resources necessary to
implement the agreements. Examples of cross-State programs include
the Chesapeake Bay Program and the Spokane-Idaho Panhandle Program.
One of the recent initiatives under the Chesapeake Bay Program is
the Chesapeake Bay Nutrient Reduction Agreement, which calls for a
40 percent reduction in NCCs and phosphorus entering the Bay system
by the year 2000, to be accomplished primarily through
Federal/State cost-share BMPs and buffer zones or setback of
sources from critical tributary areas.
In-State regional programs or districts which address water
quality concerns include the Puget Sound Water Quality Authority,
the Cape Cod Aquifer Management Project, Nebraska's Natural
Resources Districts (NRDs), plus numerous Federal water resources
and conservation administrative districts across the nation.
States establish regional programs and give them authority to
address water quality problems through legislation. Nebraska
enacted a law establishing 24 multi-county Natural Resources
Districts in 1969. These districts have taxing authority and
professional staffs.
In response to detections of nitrate in ground water and at
the request of two NRDs, Nebraska recently designated its first
Special Protection Area. The Lower Republican and Little Blue
districts have six months to draft a plan for alleviating the
contamination. The plan must include mandatory measures (such as
imposition of BMPs or restrictions on fertilizer use) as well as
education and monitoring programs.
Technical and Financial Resources
Regional bodies contribute information, planning, technical
and financial assistance to water quality protection efforts.
Contributions vary widely from body to body. The Nebraska NRDs,
for example, have staffs that range from a few people to 40-50
employees and budgets from $300,000 to over $8 million. Some of
these regional bodies do not contribute their own funding but
simply allocate appropriations from State legislatures to local
governments while others have the authority to levy taxes or charge
user fees. Collected funds may support research, monitoring, soil
testing for nitrate levels, and technical assistance for evaluating
onsite septic systems as well as administrative costs.
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Local Governments & Others
Roles and Responsibilities
NC contamination results from a variety of activities
associated with specific land uses. Since control of land use has
traditionally resided at the local level, a federal plan must
facilitate land use planning efforts. Local governments typically
implement zoning and subdivision ordinances, develop land-use
plans, implement health requirements, supply water and sewer
services, and enforce police powers. Together, these powers give
local governments the potential to play an important role in
managing or prohibiting activities that may contaminate surface and
ground waters with NCs. Additionally, local governments often have
water quality protection responsibilities under State and Federal
legislation. For example, local phased capital improvement
programs direct the location, timing and rate of development.
Coupled with federal construction seed money for waste water
treatment and State technical assistance, local government may have
sufficient start-up financing and legal authority to direct growth
away from areas of high groundwater vulnerability.
Authorities and Programs
Varied limitations (legal, fiscal, regulatory, economic, and
political) on local governments have produced a variety of
imaginative programs to mitigate water contamination. Generally,
local environmental programs mitigate pollution by (1) reducing
the levels of pollutants in a specific locations and (2) managing
the type, location, and rate of community growth. Locally
legislated programs currently include, but are not limited to:
zoning requirements [i.e. wellhead protection overlays and restric-
tions, special permitting, large-lot zoning, transfer of
development rights, planned unit development/cluster design
criteria, phased capital improvement program, performance zoning,
site plan/subdivision review]; easements [acquisitions of full (fee
simple/eminent domain) and partial (easements/covenants) interests
in land and development rights]; regulations [off-site drainage
controls, septic system regulations, chemical handling area
regulations]; acquisition of land, watersheds, and development
rights; programs to retain farmland; the retention of land within
watersheds; and monitoring activities of businesses (lawncare, golf
courses, etc.).
Technical and Financial Resources
There are, in part, two competing interests at the local
level: environmental protection and economic development. The
complexity, costs and legal authorities of environmental programs
exceeds the capacity of most local government and necessitates a
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coalition of multiple levels of government to integrate resources,
an activity atypical at the local level. By contrast, the desire to
develop and increase the local property tax base is business as
usual at the local level. Land use controls mitigating con-
tamination must be discussed in the context of a coalition because
the aggressiveness with which local environmental controls and
their financing are pursued reflects, in part, the political
balance among competing economic and environmental constituencies
for the scarce fiscal and technical resources of local government.
Localities utilize several methods to raise local funds to pay for
environmental controls: utility user fees, property taxes, bonds
to purchase land, and tax deductions.
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ACP
ADW
ASCS
BMPs
BOD5
CAA
CFC
CFR
CNS
CWA
CZHA
DO
EC
EDR
FDA
FmHA
FR
FRDS
gpd
IE
1
MCL
MCLG
metHb
mg
N
NAPAP
NAS
NAWQA
NCI
NH,
N2O
N02
N03
NOx
NOAA
NOAEL
NPDES
NPS
NPS
NSA
ODW
POTW
* DRAFT (3/5/91) *
APPENDICES
APPENDIX A—Acronyms Used
Agricultural Conservation Program, USDA
agricultural drainage well
Agricultural Stabilization and Conservation Service,
USDA
best management practices
5-day biochemical oxygen demand
Clean Air Act
chloroflourocarbon
Code of Federal Regulations
central nervous system
Clean Water Act
Coastal Zone Management Act
dissolved oxygen
European Community
electrodialysis removal
Food and Drug Administration
Farmers' Home Administration, USDA
Federal Register
Federal Reporting Data System (drinking water
violations)
gallons per day
ion exchange
liter
maximum contaminant level (SDWA)
maximum contaminant level goal (SDWA)
methemoglobin
milligram
nitrogen
National Acid Precipitation Assessment Program
National Academy of Sciences
National Water Quality Assessment, uses
National Cancer Institute
ammonia
ammonium ion
nitrous oxide
nitrite
nitrate
nitrogen oxides
National Oceanic and Atmospheric Administration
no observed adverse effects level
National Pollutant Discharge Elimination System (CWA)
non-point source (pollution)
National Survey of Pesticides in Drinking Water Wells
Nitrogen Sensitive Areas (designated in United Kingdom)
Office of Drinking Water, EPA
publicly owned (sewage) treatment works (CWA)
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FWS public water system (SDWA)
RCRA Resource Conservation and Recovery Act
RIA regulatory impact analysis
RO reverse osmosis
SCS Soil Conservation Service, USDA
SDWA Safe Drinking Water Act
SNC significant non-compliance (with MCL)
TKN total Kjeldahl nitrogen
TRI Toxics Release Inventory
TSCA Toxic Substances Control Act
UIC underground injection control (SDWA)
URTH unreasonable risk to health (SDWA)
USDA United States Department of Agriculture
US EPA United states Environmental Protection Agency
USGS United States Geological Survey
WATSTORE USGS database of water monitoring results
WHO World Health Organization, United Nations
WHPA Wellhead Protection Area (SDWA)
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APPENDIX B—Glossary
anipp - A negatively charged atom or group of atoms.
aquifer - An underground geological formation, or group of
formations, containing usable amounts of ground water that can
supply wells and springs.
biochemical oxygen demand (BOD) - A measure of the amount of oxygen
consumed in the biological processes that break down organic matter
in water. High BOD can lead to oxygen deficiency in aquatic
environments.
chemiaation - Application of inorganic fertilizers in aqueous
solution through an irrigation system.
denitrification - The anaerobic biological reduction of
nitrate-nitrogen (NO3) to nitrogen gas (N2) .
estuary - A region of interaction between rivers and nearshore
ocean waters, where tidal action and river flow create a mixing of
fresh and salt water, and may include bays, mouths of rivers, salt
marshes, and lagoons. These brackish water ecosystems shelter and
feed marine life, birds, and other wildlife.
eutrophication - The slow aging process during which a lake,
estuary or bay evolves into a bog or marsh and eventually
disappears. During the later stages of eutrophication the water
body is choked by abundant plant life as the result of increased
amounts of nutritive compounds such as nitrogen and phosphorus.
Human activities can accelerate the process.
hypoxic - A state of oxygen deficiency relative to the needs of
living organisms.
lithosphere - The earth's crust; the solid part of the earth as
opposed to its molten core.
mass balance - An accounting of all input, use, storage, and export
of a chemical or chemical compound from a given part of an
ecosystem.
naxinup eqpfc«»inant level (MCL) - The enforceable level set by EPA
for maximum permitted concentration of a pollutant in public
drinking water .
maxim*,™ contaminant level goal (MCLG) — The level of pollutant in
a public drinking water system that has been found not to pose any
health risk.
methemoqlobinemia - A condition observed primarily in infants in
which oxygen supply in the blood stream is inhibited, giving a
bluish hue to the skin. Also called "blue baby syndrome."
mineralization - The process by which organic matter is transformed
into inorganic compounds that are usable by plants.
N-nitroso compounds - Substances formed from the combination of
nitrite and nitrosatable substrates; e.g.: nitrosamines,
nitrosamides, nitrosocarbamates.
nitrate - A compound, NO3, which can exist in the atmosphere or as
a dissolved gas in water and which can be harmful to the health of
humans and animals.
nitrate-nitrogen - Nitrogen when it occurs in the form of the
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compound nitrate (NO3)
nitrification - The process whereby ammonia in water is oxidized to
nitrite and then to nitrate by bacterial or chemical reactions.
nitrite - 1. An intermediate in the process of nitrification. 2.
Nitrous oxide salts used in food preservation.
nitrogen oxides - A byproduct of combustion processes from mobile
and stationary (industrial) sources. A major contributor to acid
deposition and the formation of ground-level ozone in the
troposphere.
Tiifr-rogmnipes - A chemical compound formed from a secondary amine
and a nitrosatable substrate.
nitrosatabie substrates - Naturally occurring substances found in
many types of food such as fish, poultry, meat, dairy products and
grains. Also present in some agricultural chemicals, drugs, and
many cosmetics.
non-point source - sources of pollution loadings to water which are
diffuse in origin.
percolation - The movement of water downward and radially through
the sub-surface soil layers, usually continuing downward to ground
water.
pH - A measure of the acidity or alkalinity of a liquid or solid
material.
phenols - Organic compounds that are by-products of a number of
industrial processes. Low concentrations cause taste and odor
problems in water; higher concentrations can kill aquatic life and
humans.
point source - The Code of Federal Regulations defines a point
source to be "any discernible, confined and discrete conveyance,
including but not limited to any pipe, ditch, channel, conduit,
well, discrete fissure, container, rolling stock, concentrated
animal feeding operation, landfill leachate collection system,
vessel or other floating craft, from which pollutants are or may be
discharged. This term does not include return flows from irrigated
agriculture or agricultural stormwater runoff." (40 CFR 122.2).
reductase - An enzyme that catalyzes chemical reduction.
side-dressing - A practice by which fertilizer is applied near to
plant roots after emergence of the plant from the soil, in order to
realize use efficiency.
total fclehdahl nitrogen (TKN) - A method used to determine the
quantity of nitrogen present in water, encompassing nitrogen found
in the form of ammonia, ammonium salts, nitrates/nitrites and
organic compounds.
wellhead protection area - An area designated by a state under the
Wellhead Protection Area Program, in which authority is granted to
regulate certain land uses in the interests of protecting wellheads
and wellfields which provide a source of public drinking water.
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APPENDIX c—Agency Responsibilities
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APPENDIX D—Methodology for County-Level Manure Estimates
I have calculated the ratio of the number of pounds of
nitrogen in animal waste potentially available to crops to the
number of acres of harvested cropland, and to the number of acres
of harvested cropland excluding cropland planted in nitrogen-fixing
crops as reported in the 1987 Census of Agriculture for each county
in the U.S. The ratio is intended to show where and to what extent
animal wastes production may exceed capacity for agronomic land
application. We used statistics reflecting the estimated amount of
"nutrients which are economically recoverable" by region in
estimating the amount of nitrogen available from animal waste. The
figures come from Estimating U.S. Livestock and Poultry Manure and
Nutrient Production (USDA, 1978). The animal types, production
areas, nitrogen production estimates, and nitrogen after 25%
volatilization are listed below.
Animal type Production area
Volatilization
Beef cattle
Feeder Cattle
Dairy cattle
Fat hogs
Sheep
Laying hens
Broilers
Production area descriptions
1
2
3
4
5
6
7
8
9
10
Lbs N
3.6
0.0
20.0
20.4
103.8
55.2
102.2
98.1
4.5
3.4
3.0
0.7
0.1
Lbs N After 25%
2.550
0.000
15.000
15.300
77.850
41.400
76.650
73.575
3.375
2.550
2.250
0.525
0.075
1 Northern states - NV to VA, all states between and to the
north
2 Southern states - all not in area 1
3 ND, SD, NE, KS, AR, LA, and all states eastward
4 Western States - all not in area 3
5 Northeast, Appalachian, Corn Belt, Lake, Northern Plains, and
Northern Mountain States
6 Southeast, Northern CA, OR, and WA
7 Southern Plains
8 Southern CA, AZ, NM
9 Corn Belt, Lake Sates, SD, NE, KS, TX, KY, TN, NC, GA
10 All not in 9
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Recoverable nitrogen varies with management practices
The 1978 USDA ESCS publication, Estimating U.S. Livestock and
Poultry Manure and Nutrient Production has a table that shows the
amount of "manure and nutrients that are economically recoverable"
by region. Although the authors do not make their assumptions
about regional livestock management and manure handling practices
explicit, these factors are accounted for in the table. (Van Dyne,
p. 4).
Nitrogen production estimate for sows
The table in Estimating U.S. Livestock and Poultry Manure and
Nutrient Production does not give a figure for sows used for
breeding, so we developed one using information from the Midwest
Plan Service Livestock Waste Facilities Handbook and the USDA
Animaj. Waste Utilization on Cropland and Pastureland. The MWPS book
gives daily manure and nutrient production figures for gestating
sow and for a sow and litter. (MWPS, pg. 2.1) The USDA book shows
the nitrogen as a percentage of manure in dry weight and contains
implicit storage and handling loss coefficients. (Gilbertson, pp.
17, 22)
We assume that the sow will gestate twice for a total of 305
days and lactate twice for a total of 60 days. A gestating sow
produces 8.9 Ibs of manure per day, 9.2% of which is dry weight,
for 305 days a year. Nitrogen makes up 2.8% of the dry weight of
this manure. (MWPS, pg. 2.1) The implicit storage loss coefficient
is .714. (Gilbertson, pp. 17,22) We further assume that 25% of the
nitrogen will be lost in the first few days after application as a
result of volatilization (see below). (Gilbertson, pg. 31)
Consequently, each sow produces 3.76 Ibs of nitrogen in its
gestating periods each year that can be consumed by crops (8.9
Ibs/day x 305 days x 9.2% x 2.8% x .714 x .75 = 3.76.) A lactating
sow and its litter produce 33 Ibs of manure per day, 9.2% of which
is dry weight, for 60 days a year. The other variable are the same.
Consequently, each sow its litters produce 2.74 Ibs of nitrogen in
the two yearly lactating periods that can be consumed by crops (33
Ibs/day x 60 days x 9.2% x 2.8% x .714 x .75 = 2.74.) Thus each sow
reported in the Census and its two litters (up to the time they are
weaned 30 days after birth) produce a total of 6.5 Ibs of nitrogen
that can be consumed by crops.
Volatilization losses The nitrogen production coefficients we
are using reflect the amount of nitrogen in manure immediately
before application. Some of this nitrogen will volatilize in the
first four days after application to cropland and will not be
available for plant uptake. According to Animal Waste Utilization
on Cropland and Pastureland. it takes 1.33 units of surface-applied
134
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* DRAFT (3/5/91) *
manure to make the amount of nitrogen present in one unit of
nitrogen immediately before application available to crops after
volatilization loss following application. (Gilbertson, 31) In
other words, only 75% of the nitrogen present in manure immediately
before application will be available for plant uptake.
Consequently, we have multiplied all our nitrogen production
numbers by .75 to account for volatilization after application.
According to Van Dyne, the estimates of nitrogen economically
recoverable account for some volatilization loss. Consequently,
the estimated volatilization loss of 25% that we have used may be
too high. On the other hand, the authors of the publication with
the 25% loss figure clearly intended it to reflect losses
immediately after land application, so it should include a reduced
propensity to volatilize due to previous volatilization losses
during storage.
Data We used data from the 1987 Advance Census of Agriculture to
develop our estimates. The Advance Census does not have data on
cattle fattened on grain and concentrates or hogs and pigs in
inventory used for breeding.
In order to develop our estimates of nitrogen production, we
had to estimate the populations of the types of animals listed
above. We did this by finding the ratio of each category of animal
to a similar type of animal for which we did have data. While this
procedure undoubtedly introduces errors at the county level as
ratios of animal type vary, it does not introduce a systematic
bias.
We used the national ratio in 1982 of "beef cows in inventory"
to "cattle fattened on grain and concentrates sold," which was .81,
to estimate the number of cattle on feedlots for 1982. I keyed in
the 1987 data from the Final Census of Agriculture for "cattle
fattened on grain and concentrates sold." We used the national
ratio in 1982 of "hogs and pigs in inventory" to "hogs and pigs in
inventory used for breeding," which was .13, to estimate the number
of breeder pigs in inventory for both 1982 and 1987.
The number of cattle on range includes half the number of
cattle on feedlots. This is because feedlot animals are only
fattened on the feedlot for around 180 days. They are on pasture
for the remainder of the year.
Problems with methodology
Hissing census data The Census of Agriculture does not disclose
data for all items in all counties. Some counties have so few
producers of an item that releasing the census data collected from
individuals would reveal the size of their operations and violate
135
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* DRAFT (3/5/91) *
the confidentiality promised by census takers. The counties for
which one or more data fields was missing are indicated with an
asterisk.
Production coefficients for swine may not reflect current situation
The nitrogen production coefficients we used for hogs may not
accurately reflect current swine management practices, which may
result in greater quantities of recoverable nitrogen than the
practices of the late seventies. Hog production operations are
becoming increasingly large and producers are moving away from
feedlots to complete confinement.
The effects of large scale confinement operations are partly
accounted for in the regional Van Dyne tables. The tables show
production of 3.4 Ibs of nitrogen per animal per production period
for regions with smaller, less confined operations and production
of 4.5 Ibs in regions with larger, more confined operations. Using
the higher production coefficient (4.5 Ibs) for the regions that
had smaller, less confined operations did not alter the estimate of
total nitrogen per acre substantially. For all counties with 60 Ibs
of nitrogen per acre or more, the total nitrogen per acre was
increased by less than 10% when the higher production coefficient
was used.
We had considered presenting a range of possible nitrogen per
acre ratios, but since using the higher production coefficients for
swine did not result in a substantially different figures in
counties where the nitrogen per acre ratio was high enough to
suggest potential problems, we used the figures originally
recommended by Van Dyne in 1978.
Other production coefficients may also be outdated Van Dyne
himself suggested that the swine estimates may not accurately
reflect current practices in a conversation in July. Production of
all types of animals has shifted increasingly towards large,
concentrated, confined operations that make manure recovery easier
and may reduce runoff and leaching potential. Consequently, it is
also possible that the production coefficients for other animals
understate the amount of recoverable nitrogen. We believe that our
estimates of the ratio of Ibs of nitrogen available from animal
waste to acres of non-nitrogen fixing harvested cropland are
conservative.
136
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* DRAFT (3/5/91) *
APPENDIX E—Fertilization Rates in Major Producing States
APPENDIX F—Tons of Nutrient N Sold By State
137
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