x>EPA
EP
80-504
United States
Environmental Protection
Agency
Office of Water and
Waste Management
Water Planning Division
Washington, D.C. 20460
September 1980
440980504
Water
Executive Summary
Agricultural Land Use
Water Interaction:
Problem Abatement,
Project Monitoring,
and Monitoring Strategies
'CILCI'IONAGSNCY
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Review Notice
This report has been reviewed by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents neces-
sarily reflect the views and policies of the Envi-
ronmental Protection Agency, nor does mention of
trade names or commercial products constitute
endorsement or recommendation for use.
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Executive Summary
Agricultural Land Use Water Quality Interaction:
Problem Abatement, Project Monitoring, and Monitoring Strategies
Jochen Ktihner
Meta Systems Inc
Cambridge, Massachusetts
This report, of May 1980, for the U.S. EPA Water Planning Division's
Rural NFS Section (under Purchase Order W-5571-NASX) addressed the following
three tasks:
General categorization of agriculturally related NPS pollution prob-
lems interfacing with various receiving waters, and outlining of
potential remedies through modification of practices and introduction
of new practices and/or practice combinations.
Discussion of the requirements, method, and limitations of individual
project monitoring.
Consideration of the process/strategy of selecting projects for de-
tailed monitoring/evaluation (M/E) across the United States under
the Rural Clean Waters Program.
The basic idea underlying this report is that potential remedial actions
on the land must be geared to existing water quality (WQ) problems. Thus
only those agricultural land uses and practices that appear to cause WQ prob-
lems should be modified, and the degree of modification or the introduction
of new practices must be determined by needed water quality improvements.
This necessitates a "2-track" system for technical evaluation (Figure 1) .
First, after the water quality problem and its indicators have been described,
the sources of the problem must be detected and the potential modifications
of the pollutant load through practices/measures analyzed. Second, the desir-
able water quality must be identified and the reduction in pollutant input
necessary to achieve the water quality goal computed (including possible
instream measures). Third, the two tracks must be compared in order to deter-
mine which practices/measures are capable of reducing the input load such
that the water quality goals are met. The implementability of the measures
must finally be determined in socio-economic and institutional terms. This
scheme requires the identification of cause-effect relationships for each
project, the analysis of the pathways of pollutants, and the gearing up of
M/E efforts, after preliminary analysis, to the particular water quality
problem and its land/water setting.
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FIGURE 1. TECHNICAL PROJECT EVALUATION
INFORMATION:
RECEIVING WATER
TYPE
HYDROLOGY
CLIMATE
MORPHOMETRY
IDENTIFY SOURCES
OF WQ PROBLEM
(ANALYSIS/INSPEC-
TION)
LIST APPROPRIATE
CONTROL PRACTICES/
MEASURES (BY CATE-
GORY)/COMBINATIONS
ANALYZE THE REDUC-
TION POTENTIAL FOR
PRIME POLLUTANTS IN
TIME % SPACE (SYN-
ERGISTIC EFFECTS)
NO
IDENTIFY WO PROBLEM
(PRIMARY & SECONDARY
EFFECTS/IMPAIRMENT
0^ WATER USES)
IDENTIFY MAJOR POLLU-
TANTS/PARAMETERS RE-
SPONSIBLE FOR PROBLEM.
(STATISTICAL CHARAC-
TERISTICS/SEASONS/
OTHERS)
ANALYZE WQ IMPACT £ RE-
DUCTION NEED OF POLLU-
TANT INPUT TO ACHIEVE
DESIRABLE WQ LEVEL
(POLLUTANTS/COMBINATIONS/
IN-STREAM MEASURES)
REDUCTION OF POLLUTANTS
TO NECESSARY LEVEL FEA-
SIBLE WITH PRACTICES?
YES
EVALUATE FEASIBLE REDUC-
TION STRATEGIES WITH RE-
SPECT TO IMPLEMENTATION
CAPABILITY (IN USDA/SCS
SENSE)
IMPLEMENTATION
M/E
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Given this approach to solving agricultural pollution problems and to
monitoring the effectiveness of abatement measures, it is desirable to have
a clear idea of three things: the likelihood of encountering water quality
problems due to agricultural activities under certain conditions; how to
set up the monitoring of problems of individual projects; and how to select
projects across the United states. To obtain this general information,
variables/parametera of the land/water interface were selected, including
basic agricultural land uses, receiving waters, water quality problems and
their indicators, and potential practices/measures to improve water quality.
The following land uses were chosen:
Cropland*
nonirrigated
irrigated
Orchard/Vineyard
Grazing Land (including range, improved range, and pasture)
Animal Holding
Homestead
The following receiving water types were selected:
Lake/Reservoir
Small Stream
River
Bays (Great Lakes)
Groundwater
The following water quality problems and their indicators were investigated:
Sedimentation
Eutrophication
Salinity
Pesticides
Pathogens
BOD/Organic Material Loading
Nitrates
In this characterization "broad" water quality impacts described by
combinations of various parameters (such as eutrophication) were combined with
"specific" single parameter impacts (such as nitrate). This lumping together
is not a problem as long as the pathway of pollutants is indicated and result-
ing problems are described. Secondary impacts such as on fishing, recreation,
etc., were omitted here, since they are related to water uses that were not
explicitly addressed in this report.
Five categories of practices/measures that influence water quality were
distinguished:
*In contrast to USGS classification, pastureland is not included in crop-
land; it is assumed, however, that hayland is included, possibly as part
of a rotation.
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1) Modification of land use activities without any additional structures
and/or addition of nonstructural conservation/control practices;
2) Management strategies;
3) On-site structures attached to or associated with ongoing land use
activities;
4) Off-site structures capturing and/or modifying runoff and washoff;
5) Streambank and instream control measures.
Practices/measures for all land use activities could be fit into this
scheme. Thus examples of the first control area are chisel plowing (instead
of moldboard plowing); of the second area, timing and application of fertili-
zer and pesticides; of the third area, grassed waterways and terraces; of
the fourth area, sedimentation basins, ponds, and grassed strips; and of
the fifth area, fencing against animals and copper sulfate application against
algal bloom.
A broad identification was made, in sequential steps, of the water quality
impact of agricultural activities. These steps were:
1) The description of the pollutants resulting from certain land use
activities (Table 1);
2) A review of those pollutants that cause water quality problems (Table
2);
3) The integration of the above two steps into a simplified matrix of
potential pollution problems in the different receiving water types
resulting from agricultural activities (Table 3).
Since it is well-known that local factors influence the degree of severity
of pollution problems, the impact of local soil types, structures, erodibility,
and physiographic and climatic conditions was presented, as were examples
that clarify the significance of these factors. One example: assume an
agricultural land use affects a lake in all four water quality problem areas:
sedimentation, eutrophication, pesticides, and NO_. Given the particular
interrelationships among sediment, eutrophication, and NO -N, it is known
that erosion control alone might only reduce the sedimentation problem with-
out improving the other water quality parameters. For example, if eutrophi-
cation is phosphorus (P)-limited, erosion control is helpful; if it is light-
limited, a reduction in the fertilizer application rate is probably needed,
in addition to some erosion control measures. NO., problems can most likely
only be eliminated by reduced fertilizer application. Drainage characteris-
tics notwithstanding, NO might end up in the reservoir via interflow, a
situation not helped by phasing input, since accumulation of pollutants
is a problem in this receiving water type. Thus reducing runoff via soil
and water conservation practices (SWCP) does not help. Depending on the
type of pesticide, SWCP might have some impacts, but most likely, different
management schemes would have to be applied to mitigate the problem. There-
fore, reducing nutrient and pesticide application rates and timing their
application must be added to erosion control practices. This shows that
parameters such as sand, silt, clay, distribution of soil/sediment, adsorption
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capacity, trapping of P and nitrogen (N) in the reservoir, excessivity of N
over P with respect to algae requirements, turbidity, snowmelt, potential en-
richment of soil, and ratio of particulate P to dissolved P all play an impor-
tant role in designing the overall abatement strategy. As can be seen, an
awareness and understanding of the pathways of pollutants is essential.
Project monitoring can cover all the parameters of interest only if path-
ways of these parameters are known. This makes necessary a sound analytical
investigation of the land/water interface prior to any monitoring. Too often,
without such an investigation, the wrong parameters have been monitored or the
right parameters at the wrong location and/or frequency. Thus, five basic
questions have to be answered in setting up a monitoring and evaluation pro-
gram for an individual project:
1) What are the types of samples to be taken and measurements to be made
(constituents, flow, etc.);
2) What are the locations of sampling stations;
3) What is the frequency and duration of sampling at the stations; and
4) What are the methods to be used in sampling and measurement (i.e.,
equipment, etc.).
5) How are the data to be presented and stored for later analysis.
Generally these five characteristics of sampling programs cannot be considered
independently. However, it is unnecessary that the same characteristics
be considered for each station.
Therefore, the following steps should be taken in order to set up the
most effective monitoring program:
1) Define the critical stretches of the receiving water;
2) Describe the apparent water quality problem in quantitative terms
as much as possible;
3) State clearly which are the likely parameters that have to be con-
trolled and in which season they are of concern;
4) State clearly what the critical land areas are that determine water
quality impact and describe those individual water quality parameters
that are influenced by the critical areas;
5) Assess qualitatively the effects that various BMPs might have on
runoff and edge-of-stream load (and on water quality);
6) Attempt an analysis (possibly with regional data) of the impacts
of various practices and practice combinations on the pollutant loads,
the load distribution, and on the receiving water's quality. On
the basis of this analysis, identify the critical parameters to be
monitored.
7) Based on the problem's temporal and geographic characteristics, the
parameters of concern, and the BMP's anticipated effects, lay out the
monitoring network (including flow measurements). Since not all the
areas are similar and not all areas are treated with the same practices,
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receiving water loads (i.e., flows and concentrations) must be measured
at various points. (This is particularly important in the case of
lakes/reservoirs in order to derive a pollutant budget.)
8) Be prepared to monitor water quality and flow in creeks (draining
to critical water quality stretches) during storm events occurring
shortly after applications of fertilizer and pesticides (this generally
requires automatic sampling equipment).
9) Determine the frequency of sampling in 1) creeks/drains to the receiv-
ing water; and 2) the receiving water's critical stretch. Generally,
the frequency of monitoring has to be higher in the upstream portions
of the basin than in the downstream portions. Further, frequency
depends on the information needed for characterizing a pollution prob-
lem in a receiving water. Simply stated, when the pollution problem
is of a cumulative nature (like eutrophication in lakes/reservoirs),
the critical water quality area can be monitored relatively infrequent-
ly. However, the drainage into the major receiving water has to be
monitored on a regular basis in order to establish the input patterns.
(See also the March draft of NFS Task Force Guidance Document on Moni-
toring. )
10) Determine the appropriate length of time for a watershed to be moni-
tored. This varies according to the nature of the pollution problem,
the nature of the control of management strategy, and the length of
monitoring chosen for other watersheds providing information to the
program. Longer periods of monitoring reduce the variance of an es-
timate at a single site, leading to a tradeoff between parameter accu-
racy and monitoring duration. While long-term monitoring of projects
may be required to reduce variance, a greater diversity of projects
is desirable so that existing information might be more easily trans-
ferred to some sites that have not been monitored at all or only very
infrequently.
11) Given the analytical framework for the analysis and the need for con-
stant reassessment of the monitoring scheme and the value of the gen-
erated data, the data have to be processed and stored in such a way
that they are easily accessible and transformable. All raw data should
be kept on file. After initial collection, simple statistical manip-
ulation can be performed and simple relationships plotted. Thus various
initial questions about project performance and modeling assumptions
can be addressed along with the monitoring performance.
12) Establish a quality assurance program.
It is essential to the success of every M/E project that the data gener-
ated are constantly analyzed and the new information fed back for improvement
of the program. It is thus necessary to integrate firmly the land/water
quality analysis with monitoring and evaluation of the water quality and
the performance of the practices. This implies that the monitoring system
must be continually adjusted to the results of the monitoring and analysis;
it also means that the practices/measures must be adjusted as well. It is
obvious that, in many cases, conventional measures do not meet established
needs; they must be augmented by management measures, such as application of
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fertilizer/pesticides and their timing, in order to yield the desired water
quality results.
To facilitate selection of potential projects across the United States
for M/E, some characteristics/criteria were presented that were considered
helpful in comparing these potential projects. Given the fact that potential
projects should be identified on the basis of their water quality problems,
the following steps are envisioned in the selection process:
1) Determine the areas that exhibit agriculturally based water quality
problems, and define a project.
2) Characterize these projects according to important M/E criteria.
3) Weight the M/E criteria for final choice of projects.
Step 1 can be performed more or less along the lines of the current EPA/USDA
identification process. Potential projects can be summarized for each region
in a simple matrix (such as Table 3) where the entries would be the number
of the particular land use/water quality problems in each region. The land
use/water quality combinations that cause the most significant deterioration
of water quality are considered for implementation. If there is an obvious
tradeoff between a "large number" of specific problems (land use/water quality
combinations) and infrequent but severely impacting land use/water quality
problems, the choice must be made between the "large number" (possibly repre-
senting a typical problem) and the individual severe problem. If there is
no obvious tradeoff, additional criteria are used, such as typical hydrology,
ease of problem identification and isolation, and local capacity.
In step 2 the characterization of the projects chosen in terms of criteria
that are important for M/E project selection should proceed in two ways:
1) A determination should be made based on federal perspective whether
or not a project is typical.
2) On the basis of technical details, implementation potential, and insti-
tutional capabilities, a ranking should be made of the projects not
categorized under 1).
Various tools, especially the recent RCA studies, are available for 1)
above. For 2) some characteristics/criteria are defined that were tested
for their suitability to characterize potential M/E projects (Table 4). Not
all of these characteristics/criteria would carry the same weight (see below).
For step 3 the ranking of the projects should be based on these character-
istics/criteria, all of which can be viewed as purely descriptive, but most
of which guide comparisons in the review process. Thus the weighting should
not be static, but should reflect the information gained in conducting M/E
projects. In this way, statements can be made about each characteristic/
criterion, reflecting, more or less, the current state of knowledge.
1) In selecting projects across the United States, all areas should ideal-
ly be covered; however, it is desirable initially to focus on areas
that have cold, as well as warm, seasons.
10
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TABLE 4. PROJECT CHARACTERISTICS
1. U.S. Location
North/South//East/West (i.e., separation into dry and humid
areas and those impacted by snowfall)
2. Water Quality Problem (general)
3. Major Land Use (acres if available)
cropland (type of crop)
feedlots (covered under RCWP)
animal holdings (except feedlots)
range/pasture
mix (population canters and others)
4. Irrigation/Nonirrigation
5. Point Source Influence
point source
nonsewered/septic tanks
purely nonpoint source agricultural problem
6. Type of Pollution Problem (as defined by review of land)
erosion and associated nutrients
erosion and associated nutrients and pesticides
heavy pesticide use
7. Receiving Water (including hydrologic characteristics)
lake/reservoir
small stream
river
bay (Great Lakes)
groundwater
8. Drainage/Land Characteristics
flat, delta type
unclear drainage to critical water quality areas
clear-cut drainage
slope
11
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TABLE 4. (CONTINUED)
9. Project Area (acres)/Watershed
10. Population in Project Area
11. Critical Area (acres
ratio of critical area to project area
12. Number of Farms (in critical land area)
large ( > 200)
j- /-, -.r^ (these are not absolute limits, but reflect
medium (100-200) > _ , . . . , ,.
[ the 13 projects currently considered)
small { <100)
13. Number of Animal Facilities (in critical land area)
14. Water Use
drinking water supply
recreation (contact/noncontact)
fisheries and wildlife
agricultural and industrial water supply
15. Specific Water Quality Problems
coliform
pesticides
eutrophication (P-, N-, light-limited)
nitrate
sedimentation
salinity
16. Parameters Previously Monitored
17. Preliminary Analysis in Application (including pathway of pollutants)
18. Protective/Preventive Practices (suggested)
19. Suggested M/E plan in Project Application
20. Inclusion in 208 plan?
12
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2) A general description of the water quality problem allows a first
indication of the extent to which it can be quantitatively described.
3) It is necessary to isolate as much as possible individual, largely
homogeneous land uses in order to draw any inferences for a poten-
tial project.
4) The choice of irrigated or nonirrigated land use is largely a matter
of agency preference.
5) Any point source or septic tank influence should be minimized because
its impact cannot be easily isolated and abstracted from concentra-
tion/load estimates, especially in lake/reservoir receiving water
systems.
6) Overall analysis and evaluation are facilitated if one specific pol-
lution problem can be identified. Different problem types need
different remedies in terms of practices/measures, but the more
individual practices are eventually combined in a so-called "Best
Management Practice" (BMP), the lesser the likelihood that the effec-
tiveness of individual practices can be identified. Thus since com-
binations of practices are very unique to a specific problem, the
fewer problems involved the better and, hence,'the fewer practices
combined, the more useful the results.
7) Given the current state-of-the-art of identifying and evaluating re-
ceiving water pollution phenomena, it must be emphasized that if the
receiving water is not a lake/reservoir, it will be difficult to
measure and identify water quality impacts. There is, however, at
least one caveat to this suggestion: if this receiving water's pol-
lution problem has been present for a long time, it cannot be cleared
up quickly, because of the lake/reservoir's "memory" (e.g., nutrients
in sediments). This makes it rather unlikely that any changes in
water quality can be identified as a result of practice changes in
a period of about 5 years.
8) In order to effectively perform M/E, there should be only one drain-
age area and clear-cut drainage patterns.
9 and 11) The smaller the project's critical area with respect to the
total project basin/watershed, the more difficult it is to identify
clearly any distinct impacts; also, the smaller the ratio of receiv-
ing water surface area to watershed area, the lesser the likelihood
that changes due to isolated land practices can be extracted from
water quality data. Furthermore, the type of analysis applied is
somewhat influenced by this configuration; in impoundments with
extremely short hydraulic residence times, seasonal variations of
loadings may become of overriding importance.
10) Since permanent and temporary population may contribute to pollution
(see 5 above), it is advisable to have as small a population as pos-
sible in the project area (including the impacted receiving water
area) .
13
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12) The smaller the number of farms the better, since diversified owner-
ship of the lands under investigation makes it more difficult to
monitor the agreed-upon practices. This is especially true if
measures other than structures have to be used.
13) Since a large number of animal holding facilities makes identifica-
tion of the problem area difficult, it is desirable to have a rela-
tively small, observable number of facilities in the area.
14) Definite water use characterization of the critical water quality stretch
is important, since it implies standards for respective water quali-
ty parameters that would have been set by the state having jurisdic-
tion over the problem area. Such standards would provide for clearly
identifiable thresholds to be reached in the receiving water improvement.
15) Some of the specific water quality problems occur mostly in combina-
tion, such as eutrophication, sedimentation, and NC>3. This influ-
ences the set of practices to be applied (and monitored) and the
monitoring requirements (space and time) in the receiving water.
Since each pollution problem is characterized by a unique setting,
individual practices and combinations of practices must be analyzed
in terms of individual pollutants and their behavior in the specific
setting. The more interplay there is between problems, the more
difficult analysis and monitoring become and thus the more careful
their set-up must be.
16) Historical data can give some clue about past water quality trends,
e.g., the time period a eutrophication problem has prevailed. But
the data base is generally inadequate to draw any conclusions about
the land use activities that caused the problem. This means that
baseline data are valuable but not essential to the choice of M/E
projects.
17-20) The more analysis performed prior to any monitoring exercise the
better. The relative level of required analysis depends on the pol-
lutant/practice/receiving water combination for each area (see 15).
On the basis of the above discussion, it is felt that the following factors
are most important in selecting M/E projects at this time:
ease of identifying the water quality problem and its cause;
eutrophication problems in lakes/reservoirs or in other relatively
stagnant water bodies generated in a clearly identifiable upstream
area, with focus on those eutrophication problems whose history is
only relatively short;
the potential for reducing the "reason for the water quality problem"
to one land use type (e.g., cropland versus animal holding) and thus
the avoidance of "mixed land uses";
avoiding areas where uncontrollable septic tank influences are possible;
given the interest in tradeoffs of point source vs. nonpoint source,
isolation of a project in which correction of both problems can be
monitored (it would be helpful to have historical data on the point
source effluent);
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avoiding areas with more than one drainage pattern.
Finally, since the utilization of the data is important, their handling
and storage should be comparable to the EPA (STORET) and USGS systems. In
this way the new data can be fit with other data sources to perform local
and regional analysis of the type needed to initially assess the water quality
problems of certain areas. (See discussion of individual project monitoring.)
a U. S. GOVERNMENT PRINTING OFFICE 1980 341-082/102
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