North Carolina
Cooperative Extension Service


The NCSU Water Quality Group Newsletter

Number  72	              July 1995			ISSN 1062-9149


Cost-Effectiveness of Agricultural BMPs for
Nutrient Reduction in the Tar-Pamlico River Basin (NC)

John P. Tippett* and Randall C. Dodd
Center for Environmental Analysis, Research Triangle Institute

* John Tippett is now at Friends of the Rappahannock, Fredericksburg, VA.


The Tar-Pamlico Nutrient Trading Program was adopted in 1989 by the North Carolina Division of Environmental Management (NCDEM) as an innovative approach to managing nutrient inputs from both point and nonpoint sources in one of the state's major river basins. The premise of the program is that cost-sharing for agricultural best management practices (BMPs) is more cost-effective in reducing nutrient loading than controlling nutrients from point sources. The initial phase of the program, which ended in 1994, is being evaluated to determine what changes should be made for the future. While municipalities have funded research and development activities, formal trading (use of discharger funds to implement BMPs) has not occurred to date because point source loadings have not exceeded the basin-wide limits set by NCDEM. Nevertheless, the trading program is generally considered a success by agencies and dischargers because of the conceptual and institutional framework established.

The goal of the project, entitled Cost Effectiveness of Agricultural BMPs for Nutrient Reduction in the Tar-Pamlico Basin (Tippett and Dodd, 1995), was to provide accurate and up-to-date information on which to base decisions concerning nutrient trading payments in the next phase of the Trading Program. Cost-effectiveness estimates for cost-shared agricultural BMPs in the Tar-Pamlico river basin were developed by Research Triangle Institute for NCDEM. This article presents a summary of results based on the final project report.

Project Objectives


BMP unit costs were calculated for major cost-shared practices in the Tar-Pamlico basin. Values were based on NC Division of Soil and Water Conservation records and were adjusted to include farmer contributions, operation and maintenance costs, area benefited, and practice life expectancy.

The project team endeavored to obtain and present the most recent and geographically relevant cost and effectiveness information available. A literature review was conducted to determine the most relevant studies on which to base estimates of BMP effectiveness in the Tar-Pamlico basin. Preference was given to data collected within the Tar-Pamlico basin. When data from within the basin were not available, studies conducted in similar geographic provinces or eco-regions were used. Effectiveness data specific to the basin were available for animal waste management practices and for water control structures (Evans et al., 1984, 1991). The effectiveness of conservation tillage practices was estimated based on results of studies in the Chesapeake Bay watershed for the Southeastern Plains and Middle Atlantic Coastal Plains ecoregions (Casman, 1990; Camacho, 1990, 1992). The effectiveness of terracing practices was estimated based on pertinent literature (Casman, 1990; Langdale et al., 1985; Ellis et al., 1985). Effectiveness of vegetated filter strips, field borders, and stripcropping was determined based primarily on Chesapeake basin studies that used filter strips of similar size to those cost-shared in the Tar-Pamlico basin (Casman, 1990; Dillaha et al., 1988; Magette et al., 1987). For the remaining practices, effectiveness data were not available.

Cost data used represented the direct cost of implementing BMPs. Other less direct costs such as: 1) opportunity costs from loss of productive land to BMPs and 2) costs of not implementing BMPs, such as higher fertilizer costs and off-site costs resulting from pollution impacts, are not addressed.

It should be emphasized that the inherent variability associated with both BMP costs and effectiveness introduces substantial uncertainty into the development and use of cost-effectiveness values. The project team tried to fully document assumptions and limitations associated with the cost-effectiveness values.


Recommendations for Targeting Cost-Share Funds for Reducing Nutrient Loading

1) The North Carolina Agricultural Cost-Share Program could place a higher priority on nutrient (especially nitrogen) management.

Nutrient management has been proven to be a cost-effective strategy for reducing both edge-of-field and watershed loading from agricultural lands. "Nutrient management" in this context refers to both the approved BMP and the broader concept of focusing management attention on optimizing and managing farm systems to minimize nutrient losses to the environment. Nutrients supplied in excess of the amount required by crops result in a pool of residual nutrients in the soil. Over time, the size of the residual pool directly influences the magnitude of losses of available or mobile forms to surface water, ground water, and the atmosphere.

Virginia is an example of a state with an active nutrient management program staffed with 10 field nutrient management specialists. As of October 1993, over 1,000 nutrient management plans for 240,000 acres of cropland had been developed. Nutrient reductions from these activities are estimated at 5.2 million pounds of nitrogen and 4.4 million pounds of phosphorus (Danielson, 1994). Resource management plans are required in resource protection areas of the coastal zone under the Chesapeake Bay Preservation Act.

The most important opportunity for improving nutrient management is to refine recommendations for application of synthetic fertilizers. Although nitrogen is supplied to cropping systems from many sources, including legumes and manures, most adjustments to the total nitrogen applied to cropping systems come by refining the quantity, location, and time of year that producers apply synthetic fertilizers containing nitrogen. Applications of synthetic fertilizers containing nitrogen are easier to manage because the amount of nitrogen applied is known. Legumes and manure may be used to improve soil quality and as valuable sources of nitrogen. The most important way to improve nitrogen management, therefore, is to reduce supplemental applications of nitrogen to account for nitrogen supplied by legumes and manures.

Recommendations for application of synthetic fertilizers containing nitrogen can also be improved by setting realistic yield goals. As a crop's yield increases, the crop's need for nitrogen increases, at least initially. The dilemma for producers is that nitrogen must be applied before the crop yield is known. Nitrogen recommendations, therefore, must be based on some expectation of crop yield. For many crops, nitrogen requirements and recommendations are based on yield goals (the yield expected by the producer under optimum growing conditions). Supplying nitrogen needed for crop growth during the period when it is most needed can be an important way to improve nutrient management. Thus, fertilizers containing nitrogen should be applied during and/or after planting whenever possible.

2) Cost-sharing of single-objective best-management practices is not the most cost-effective approach for soil and water quality programs at the farm level.

Inherent links exist among the components of a farming system and the larger landscape. Adoption of a tillage system that increases soil cover to reduce erosion, for example, may require changes in the methods, timing, and amounts of nutrients and pesticides applied. Failure to recognize and manage these links increases the cost, slows the rate of adoption, and decreases the effectiveness of new technologies or management methods. Development of innovative, economically viable, sustainable, and holistic farming systems should be accelerated to meet long-term water quality goals.

3) Increasing cost-effectiveness of cost-shared BMPs will require a greater commitment to education and technical assistance.

An increased emphasis on nutrient management is essentially an investment in implementing education, technical assistance, and improved management. Technical assistance is needed to establish appropriate nutrient budgets and application rates, based upon manure and soil testing. The goal is to have no excess nutrients lost into the ecosystem. qAlthough there are associated technical assistance costs, nutrient management plans can be expected to provide cost savings to the landowner, which makes the concept attractive and enhances the potential for voluntary adoption.

A systematic institutional framework that captures all aspects of nutrient management does not currently exist in the basin, although the North Carolina Cooperative Extension Service has recently begun training field staff. To ensure long-term success, trading program participants must determine how to administer improved nutrient management.

The project team did not attempt to quantify the cost-effectiveness of public education programs outside the realm of cost-sharing. However, the team believes that enhanced educational efforts can be highly cost-effective and should be given high priority as a means of achieving nutrient reductions goals. Mechanisms should be developed to augment public sector efforts to deliver technical assistance and to certify the quality of technical assistance provided through these channels. Crop-soil consultants, dealers who sell agricultural inputs, soil testing laboratories, farmer-to-farmer networks, and nonprofit organizations are increasingly important sources of information for producers. Soil and water quality programs need to take advantage of the capacity of the private and nonprofit sectors to deliver information.

4) The Nutrient Trading Program is in a position to take an active approach to restoring and protecting land uses and land cover types that provide positive water quality benefits. The cost-effectiveness of this approach needs to be determined.

Additional efforts are needed to encourage protection and restoration of river corridors. While the project team did not attempt to quantify the cost-effectiveness of wetland or riparian protection and restoration in reducing nonpoint source loading, there is a growing awareness of the importance of doing so (Dodd et al., 1993). Buffer zones can include natural riparian corridor vegetation, simple strategically placed grass strips, or sophisticated artificial wetlands. Federal, state, and local government programs to protect existing riparian vegetation should be promoted. The creation and protection of field and landscape buffer zones should augment, not be substitutes for, efforts to improve farming systems.

5) Information specific to nonpoint source nutrient management activities in the basin is needed.

The increasingly sophisticated questions being asked about the effectiveness of nonpoint source management efforts require increasingly sophisticated information. The project team recommends that greater effort be made by all participants and stakeholders to develop a focused research, monitoring, and information management strategy. The following information needs to be made more accessible: farming, forestry, and development practices being employed; proximity of operations to surface waters or vulnerable ground water; the potential leaching or runoff for given practices, soil types, and topography; and the location of valuable forest and wetland areas that provide buffering capabilities. Obtaining this information will require an increased commitment to the process of monitoring and closer coordination by all parties involved. Positive steps are underway in this regard, such as the funding of demonstration projects to improve information about BMP effectiveness. However, there is still a great need for a strategic planning process to ensure that future information requirements will be met.

For Further Information Contact

Randall C. Dodd, Center for Environmental Analysis, Research Triangle Institute, P.O. Box 12194, Research Triangle Park, NC 27709-2194


Camacho, R. 1990. Agricultural BMP Nutrient Reduction Efficiencies. Chesapeake Bay Watershed Model BMPs. ICPRB Report 90-07. Interstate Commission on the Potomac River Basin. Rockville, MD.

Camacho, R. 1992. Financial Cost Effectiveness of Point and Nonpoint Source Nutrient Reduction Technologies and the Chesapeake Bay Basin. Report #8. ICPRB Report 92-4. Interstate Commission on the Potomac River Basin. Rockville, MD.

Casman, E. 1990. Selected BMP Efficiencies Wrenched from Empirical Studies. ICPRB Report 90-10. Interstate Commission on the Potomac River Basin. Rockville, MD.

Danielson, L. 1994. NC State University. Personal communication.

Dillaha, T.A., J.H. Sherrard, D. Lee, S. Mostaghimi, and V.O. Shanholtz. 1988. Evaluation of vegetated filter strips as a best management practice for feedlots. J. Water Pollut. Control. Fed., 60(7):1231-1238.

Dodd, R.C., J.M. McCarthy,, W.S. Cooter, and W. Wheaton. 1993. Riparian Buffers for Water Quality Enhancement in the Albemarle-Pamlico Area. Research Triangle Institute, Research Triangle Park, NC.

Ellis, B.G., A.J. Gold, and T.L. Loudon. 1985. Soil and nutrient runoff losses with conservation tillage. In: D'itri, F.M. (ed.) A Systems Approach to Conservation Tillage. Lewis Publishers, Inc. Chelsea, MI.

Evans, R.O., P.W. Westerman, and M.R. Overcash. 1984. Subsurface drainage water quality from land application of swine lagoon effluent. Transactions of the ASAE. American Society of Agricultural Engineers. 0001-2351/84/2702-0473502.00.

Evans, R.O, J.W. Gilliam, and R.W. Skaggs. 1991. Controlled Drainage Management Guidelines for Improving Drainage Water Quality. Publication Number AG-443. North Carolina State University Cooperative Extension Service. Raleigh, NC.

Langdale, G.W., R.A. Leonard, and A.W. Thomas. 1985. Conservation practice effects on phosphorus losses from Southern Piedmont watersheds. J. Soil and Water Cons. 40(1): 157-161.

Magette, W.L., R.B. Brinsfield, R.E. Palmer, J.D. Wood, T.A. Dillaha, and R.B. Reneau. 1987. Vegetated Filter Strips for Agricultural Runoff Treatment. USEPA Region III, CPB/TRS 2/87, Philadelphia, PA.

Tippett, J.P. and Dodd, R.C. 1995. Cost-Effectiveness of Agricultural BMPS for Nutrient Reduction in the Tar-Pamlico Basin. Center for Envir. Analysis, Research Triangle Institute, Research Triangle Park, NC. 81p.


The following article is based on a fact sheet prepared as part of a series of 10 technical fact sheets designed to share the lessons learned from the Rural Clean Water Program (RCWP) (Gale et al., 1993) about nonpoint source pollution control projects with water quality and other natural resource professionals. Each fact sheet includes examples from RCWP projects to illustrate key points. (See the Information section of this issue for information about ordering the fact sheets.)

Identifying and Documenting a Water Quality Problem

Deanna L. Osmond, Steven W. Coffey, Judith A. Gale, and Jean Spooner
NCSU Water Quality Group

One of the most critical steps in controlling agricultural nonpoint source (NPS) pollution is to correctly identify and document the existence of a water quality problem. A water quality problem may be defined either as a threat or impairment to the designated use of a water resource. The designated use of a water resource is set by each state's water quality agency and includes categories such as human consumption, agriculture, aesthetics, and recreation.

Proper identification and documentation of a water quality problem requires gathering existing data from past or ongoing water quality studies. If adequate water quality data are not available to clearly document the problem and its source, a water quality problem identification and documentation monitoring program should be initiated. Monitoring should include both storm and baseflow sampling of surface water over a 6-18 month period. Ground water monitoring may also be needed. Depending on the pollutant of concern, water quality monitoring may require measurements of chemical, physical, and biological factors.

Clear problem identification and documentation should lead to a water quality problem statement that:

Assumptions about the association between pollutants and impairments should be stated. Any habitat attributes found to limit ecological health should also be included.

The water quality problem statement provides the basis for a strategy to effectively remediate a water quality impairment and enhance the designated water resource use. The strategy guides the selection and placement of best management practices (BMPs) designed to reduce, remediate, or retard specific pollutants. A clear problem statement will also help build community consensus about the problem. Communities are generally willing to devote the money and time necessary to combat NPS pollution only when they are convinced that a significant problem or threat exists and that it can be rectified.

The Importance of Problem Identification and Documentation

The diffuse nature and spatial and temporal variability of NPS pollution make it a difficult problem to treat. Pollutant sources can be hard to identify and impacts may be subtle. Therefore, without adequate water quality problem documentation, NPS pollution cannot be successfully controlled.

Many of the 21 projects selected to participate in the RCWP had thorough water quality impairment investigations prior to project selection. The availability of water quality data facilitated preparation of well-crafted water quality problem statements that led to actions that enhanced water quality.

Gathering Existing Data for Water Quality Problem Identification and Documentation

The first step in identifying and documenting a water quality problem is to gather existing data on the water resource and the watershed. Water resource information includes past or ongoing water quality studies. Information may be available from state water quality agencies, U.S. Fish and Wildlife Service, U.S. Department of Agriculture (USDA) - Forest Service, or the U.S. Geological Survey.

Land use, soils, hydrologic, and climatic data should be compiled. A land use map is one of the most important tools for watershed managers. Land use classifications include agricultural lands, animal operations, residential areas, industrial facilities, mining operations, parks, forests, and wetlands. Basic climatic information can be used to evaluate the times of the year when pollutant loads are greatest and when drought or other factors are affecting water resource data.

Data for the watershed analysis may be available from local health or planning departments, state natural resource agencies, USDA - Natural Resource Conservation Service (state or local offices), USDA - Consolidated Farm Services Agency, National Oceanic and Atmospheric Administration, Soil and Water Conservation Districts, or county or regional Extension Service offices.

When existing data are not adequate to document a water quality problem, additional monitoring is needed.

Monitoring for Problem Documentation

Program Design

The monitoring objective is to locate pollutant sources and ecological conditions contributing to the problem. The monitoring program must be designed such that at its conclusion a clear statement of the water use impairments, the primary pollutants, and the pollutant sources can be written.

The monitoring program should sample both ambient and stormwater quality. Baseflow monitoring of surface water documents ambient water quality conditions and problems. Storm sampling is useful for documenting the magnitude of hydrologic and pollutant impacts. For ground water monitoring, wells specifically constructed for monitoring generally yield more reliable data than existing domestic wells.

The physical properties, chemical constituents, biological organisms, and habitats monitored will depend on the water quality impairment and the extent to which the water resource has already been studied. Physical assessment monitoring includes such variables as water temperature, turbidity, sedimentation, and ground water elevation. Chemical assessment consists of monitoring inorganic (such as nitrate, ortho-phosphate, or metals) and/or organic constituents (such as pesticides or benzene). Biological monitoring should be used to assess impacts on aquatic life, and may include monitoring variables such as coliform bacteria, benthic macroinvertebrates, or fish. Monitoring macroinvertebrate or fish habitat may be important for characterizing the ecological integrity of the water resource.

Depending on the water resource being studied, monitoring stations for surface water may be established at: edge of field; tributaries; main-stem streams; or estuaries, lakes, reservoirs or wetlands. For ground water, stations may be needed: aquifer-wide, in certain portions of an aquifer, at specific sites or locations where particular practices are in use, or at specific intervals within the aquifer.

Tributary stations are often useful for identifying pollutant sources and the magnitude (load) of the pollutant. Simply monitoring the main-stem stream (primary drainage channel or lake) may be inadequate to identify sources of pollutants because the receiving water dilutes and assimilates tributary inputs, making identification of specific sources difficult. Tributary stations should be located immediately above and below suspected NPS pollution discharge areas to facilitate pollutant source identification.

Data collected at main-stem stream stations provide an aggregate of the water conditions upstream. The water quality variables measured at the main-stem stream station should match those monitored in tributaries.

Monitoring stations located in reservoirs, lakes, estuaries, or wetlands can provide useful information about the amount and fate of pollutants reaching the water resource. These stations should be strategically positioned to evaluate the impact of the pollutant on the designated water use.

Monitoring Duration and Frequency

Monitoring aimed at problem identification and documentation should usually be conducted for at least 6 to 18 months. However, watersheds with complex hydrologic conditions may require more than 18 months of monitoring for adequate water quality identification and documentation.

For continuous streams, monitoring of physical and chemical constituents should occur with sufficient frequency to ensure that water quality changes caused by climatic impacts and watershed activities can be accounted for in the analysis. The timing of biological monitoring should correspond to the type and stage of the organism being documented. Guidance on timing for biological monitoring is available from state water quality agencies.

The timing of water quality monitoring activities should also be a function of the monitoring objective. For example, timing of storm sampling is critical if the project team is trying to determine load. Water quality samples should be taken during the rise, peak, and fall of stream level during runoff.

Pollutant Budget

Existing watershed data and additional monitoring may be insufficient to entirely clarify the exact nature of the water quality problem. In some NPS projects it may be necessary to quantify the relative proportion of the pollutant contributed by each source (create a pollutant budget). For example, in the Tennessee RCWP project, where several sources of sediment contributed to the siltation of Reelfoot Lake, a pollutant budget was not constructed for the lake. The consequence of this lack of information about the relative proportion of sediment entering the lake from the various sources was that critical areas contributing the greatest amount of sediment were not correctly identified and the most effective BMPs were not implemented.

The Importance of Preparing a Water Quality Problem Statement

After all pertinent preliminary water quality information has been obtained, water quality data have been collected, and a pollutant budget prepared (if necessary), a detailed water quality problem statement should be written. A comprehensive problem statement describes the water resource; the water quality impairment or threat to designated use; habitat limitations; and the type, source, and magnitude of the pollutants. The problem statement is essential because it clearly states the water quality impairment and its sources. The problem statement can be used by the project team as a guide in selecting and siting appropriate BMPs. By providing a clear explanation of the problem and its causes to community members, a comprehensive statement also contributes to consensus building, a key factor for project success.


Allen, L.H., Jr., J.M. Ruddell, G.J. Ritter, F.E. Davis, and P. Yates. 1982. Land Use Effects on Taylor Creek Water Quality. In: Proc. Specialty Conference on Environmentally Sound Water and Soil Management. American Society of Civil Engineers, New York, NY. p. 67-77.

Fredrico, A.C., K.G. Dickson, C.R. Kratzer, and F.E. Davis. 1981. Lake Okeechobee Water Quality Studies and Eutrophication Assessment. South Florida Water Management District (SFWMD), Technical Publication #81-1, West Palm Beach, FL. p. 270.

Gale, J.A., D.E. Line, D.L. Osmond, S.W. Coffey, J. Spooner, J.A. Arnold, T.J. Hoban, and R.C. Wimberley. 1993. Evaluation of the Experimental Rural Clean Water Program. NCSU Water Quality Group, Biological and Agricultural Engineering Department, North Carolina State University, Raleigh, NC, EPA-841-R-93-005, p. 559.


Section 319 National Monitoring Program Brochure

Osmond, D.L., D.E. Line, and J. Spooner. 1995. Section 319 National Monitoring Program: An Overview. NCSU Water Quality Group, Biological and Agricultural Engineering Department, North Carolina State University, Raleigh, NC. 13p.

An attractive 13-page brochure explaining the Section 319 National Monitoring Program, and illustrated with color photographs, has recently been produced by the NCSU Water Quality Group and printed by U.S. EPA's Nonpoint Source Branch. On-going projects in Arizona, California, Idaho, Illinois, Iowa, Michigan, Nebraska, North Carolina, Pennsylvania, Vermont, and Wisconsin are highlighted in the report.

The brochure may be ordered (free) using the enclosed publications order form or by writing to Publications, NCSU Water Quality Group, 615 Oberlin Rd., Suite 100, Raleigh, NC 27605-1126, Tel: 919-515-3723, Fax: 919-515-7448, email: (please refer to WQ-90 when placing your order).

Fact Sheets on Lessons Learned
from the Rural Clean Water Program

The NCSU Water Quality Group recently published a series of 10 technical fact sheets designed to share lessons learned from the Rural Clean Water Program (see NWQEP NOTES issue # 58, published in March 1993, for more information) about nonpoint source pollution control projects with water quality and other natural resource professionals. The fact sheets were produced with support from the U.S. Department of Agriculture - Extension Service.

The 10 fact sheets address: 1) contributions and successes of the RCWP, 2) planning and managing a successful project, 3) selecting a project, 4) identifying and documenting a water quality problem, 5) critical areas, 6) systems of best management practices, 7) the role of information and education, 8) farmer participation, 9) monitoring land treatment, and 10) linking water quality trends with land treatment trends. Each fact sheet includes examples from several RCWP projects to illustrate key points.

The fact sheets may be ordered (free) using the enclosed publication order form or by writing to Publications, NCSU Water Quality Group, 615 Oberlin Rd., Suite 100, Raleigh, NC 27605-1126, Tel: 919-515-3723, Fax: 919-515-7448, email: (please refer to WQ-89 when placing your order).

Monitoring Protocols to Assess
Trout Spawning Habitat

Maret, T.R., T.A. Burton, G.W. Harvey, and W.H. Clark. 1993. Field testing of new monitoring protocols to assess brown trout spawning habitat in an Idaho stream, North American Journal of Fisheries Management 13(3):567-580.

Research on new protocols for assessing brown trout spawning habitat conducted as part of the Rock Creek (Idaho) Rural Clean Water Program project has been published in the North American Journal of Fisheries Management. According to the protocols, incubation success in artificial egg pockets is measured in terms of intra-gravel dissolved oxygen (IGDO), percent fine sediment in the substrate, and survival of embryos and alevins to emergence. Significant positive relationships were found between IGDO saturation and survival to emergence, while inverse relationships were noted for percent fine sediment and survival.

For reprints, contact: William H. Clark, Division of Env. Quality, Idaho Department of Health and Welfare, 1410 North Hilton St., Boise, ID 83720-9000, Tel: 208-334-0502, Fax: 208-334-0576 or Terry Maret, U.S Geological Survey, 230 Collins Rd., Boise, ID 83702, Tel: 208-362-9027.


NWQEP NOTES is issued bimonthly. Subscriptions are free within the United States (contact: Publications Coordinator at the address below or via email at A list of publications on nonpoint source pollution distributed by the NCSU Water Quality Group is also available with each (hard copy) issue of the newsletter.

I welcome your views, findings, information, and suggestions for articles. Please feel free to contact me.

Judith A. Gale, Editor
Water Quality Extension Specialist
North Carolina State University Water Quality Group
Campus Box 7637
North Carolina State University
Raleigh, NC 27695
Tel: 919-515-3723
Fax: 919-515-7448

Production of NWQEP NOTES, the NCSU Water Quality Group Newsletter, is funded through U.S. Environmental Protection Agency Grant No. X818397.