|
Improved Cost Estimates for Agricultural Conservation Practices
Mark R. Deutschman1,*, Sarah Koep1,2
Published in Applied Engineering in Agriculture 38(3): 539-551 (doi: 10.13031/aea.14677). Copyright 2022 American Society of Agricultural and Biological Engineers.
1 International Water Institute, Fargo, North Dakota, USA.
2 Currently at Barr Engineering, Duluth, Minnesota, USA.
* Correspondence: mark@iwinst.org
The authors have paid for open access for this article. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License https://creative commons.org/licenses/by-nc-nd/4.0/
Submitted for review on 18 May 2021 as manuscript number NRES 14677; approved for publication as a Research Article by Associate Editor Dr. Yongping Yuan and Community Editor Dr. Kyle Mankin of the Natural Resources & Environmental Systems Community of ASABE on 23 March 2022.
Highlights
Abstract. The cost to achieve water quality goals is an essential piece of information necessary for assessing whether the expected societal benefits are worthy of investment.Within the United States, taxes generate the “public money” to pay to improve water quality. State and Federal Agencies distribute the public’s money to local governments and landowners as grants and cost-share to implement agricultural conservation practices (“practices”). Comparing the cost to improve water quality and the anticipated public benefit helps inform the investment decision.
The lack of a robust method for estimating the cost of practices and developing a Water Quality Strategy hampers the ability to compare cost and benefits. Within Minnesota and North Dakota, Water Quality Practitioners commonly use the Prioritize, Target, Measure Application (PTMApp) to develop strategies to improve water quality. PTMApp utilizes the Environmental Quality Incentives Program payment as a surrogate to estimate practice cost. The Environmental Quality Incentives Program payment is a percentage of the estimated cost to implement a typical practice scenario, excluding the labor to plan, design and permit the practice; inspect the practice during construction; operate and maintain the practice; finance costs; and in most cases forgone income.
We addressed the need for estimates of practice cost by developing Useful Life Total Costs (UTLCs) for 23 agricultural conservation practices. Useful Life Total Costs incurred throughout the practice life cycle begin with planning and end with reconstruction to maintain proper function. We developed multiple ULTCs (year 2020) for each practice by bracketing the range of design variations and sizes. Legacy PTMApp costs ranged from 1% to 55% of the UTLC, confirming underestimation of the actual practice costs.
Cost functions developed by selecting the best-fit line between the ULTCs and a predominant practice physical characteristic are useful for developing Water Quality Strategies. The cost functions, recently incorporated into PTMApp, considerably improve the ability to estimate the actual cost to achieve water quality goals and societal benefits.
The cost of achieving water quality goals within a watershed is critical information for determining whether to invest in the anticipaed societal benefits. Taxation generates the “public money” used by state and federal governments to improve water quality in the United States. State and federal agencies distribute public funds to local governments and landowners in the form of grants and cost-share to help implement practices. The foundation for constructive public debate is the comparison of the cost of improving water quality and the anticipated public benefits. Publicly disclosing cost and benefit information increases transparency in decision-making and establishes expectations for the use of public funds.
A Water Quality Strategy guides efforts to improve water quality (Yuan et al., 2002; Arabi et al., 2006; Kalcic et al., 2015; Fox et al., 2021) by identifying the implementation actions for managing runoff and reducing soil and nutrient loss from agricultural lands. The Water Quality Strategy provides details about the set of practices believed necessary to achieve the water quality goals. These details include the number of practices by type, positions within the watershed, water quality value and cost-effectiveness, collective performance of the practices in meeting water quality goals and total cost.
Assessing the viability of achieving water quality goals necessitates cost information. Water quality goals are practicable when the cost of achieving the goal is reasonable in comparison to the societal benefits realized. The water quality goal specifies the maximum allowable level of a substance, most commonly sediment and nutrients (phosphorus, nitrogen), that a lake, reservoir or stream can receive. Maintaining the amount (i.e., load) below the allowable level presumably results in the desired societal benefits. Agency policy, an assessment of beneficial uses, or the completion of a Total Maximum Daily Load determine allowable levels. A portion of the load allocation from a Total Maximum Daily Load represents the maximum allowable level from agricultural lands. By design, the Water Quality Strategy portends reducing loads to the maximum allowable level.
Methods to optimize the process of selecting the “best” practices to achieve allowable levels within a watershed require information about practice cost and cost-effectiveness (Veith et al., 2001; Srivastava et al., 2002; Yuan et al., 2002; Veith et al., 2003; Bracmort et al., 2004; Arabi et al., 2006; Fox et al., 2021; Kaini et al., 2012). Cost-effectiveness defined as the annual load reduction per unit cost differs for each practice. Practice effectiveness for reducing loads varies depending upon design and watershed position. Cost varies because each practice is comprised of unique features.
Because it represents water quality value, information about practice cost-effectiveness aids in identifying the set of “best” practices to achieve water quality goals (Liu et al., 2019). Water quality value is greater for those practices with small (e.g., $/lb) cost-effectiveness values. Practice cost-effectiveness can be combined with other factors (e.g., landowner acceptance of a practice) to improve the ability to select the “right set” of practices for achieving water quality goals, leading to a more realistic estimate of the funding needed to implement the practices included in the Water Quality Strategy.
The methods used to estimate practice costs and as a result, cost-effectiveness differ in their complexity. A common method for estimating practice cost relies on using historical amounts paid for implementation (Gitau et al., 2006; Price et al., 2021). The mean or median historical value represents a typical cost for the practice.
A practice cost can also be represented by a unit cost (e.g., $/surface area) applied to a design characteristic (e.g., surface area) (Kaini et al., 2012; Kaufman et al., 2021). Landowner incentive payments made through the Environmental Quality Incentives Program (EQIP) have served as a surrogate for unit cost (BWSR, 2021).
Cost functions are widely used in optimization studies to estimate practice costs (Bracmort et al., 2004; Arabi et al., 2006; Kalcic et al., 2015). The cost function includes specific terms for practice establishment, annual maintenance and forgone income. Establishment cost can be estimated using the historical amount spent or a unit cost. The annual maintenance cost is often estimated as a percentage of the establishment cost. Removing land from agricultural production incurs an additional cost because of yield and revenue loss; i.e., opportunity cost or forgone income. The amount of forgone income depends upon the historical yield and crop rotation.
The practice implementation process involves many steps including planning, permitting, surveying, design, construction, operation and maintenance and financing (i.e., useful life). Each step has an associated cost, some such as operation and maintenance, for the entire practice life cycle. The amount of time following construction until replacing the practice is necessary to restore original function (assuming performance of routine maintenance) is the practice life cycle. Each year after construction, there is a loss of income and interest on the loan. Even thorough practice cost estimates (Christianson et al., 2013; Tyndall and Bowman, 2016) rarely account for all of the Useful Life Total Costs (ULTC) components.
The methods for estimating practice cost share several challenges. A description of each cost component should accompany every expression of cost. Practice costs can easily represent different steps in the implementation process. Material costs and contractor experience with constructing practices can vary regionally affecting cost.
Because of the difficulties with estimating practice costs, Water Quality Practitioners within Minnesota and North Dakota frequently employ the unit cost method, with the EQIP payment serving as a surrogate for the unit cost. The Natural Resources Conservation Service (NRCS) annually publishes EQIP payment schedules. The EQIP payment is a percentage of the estimated cost to implement a typical practice scenario, excluding the labor to plan, design and permit the practice; inspect the practice during construction; operate and maintain the practice; finance costs; and in most cases forgone income.
The lack of robust cost estimates for practices based on their useful life hampers our ability to compare cost and benefits and understand the societal cost for achieving water quality goals. We developed ULTCs for 23 different practices to address the need for practice cost estimates for use when developing Water Quality Strategies. We developed multiple ULTCs (year 2020) for practices bracketing the range of design variations and sizes. A best-fit line between the ULTCs and a predominant physical characteristic driving cost resulted in a mathematical (“cost”) function for each practice. The cost functions recently incorporated into a computer application known as the Prioritize, Target, Measure Application (PTMApp) (International Water Institute, 2020), which is widely used within Minnesota and North Dakota, improve the ability to weigh the cost and benefits of a Water Quality Strategy.
Materials and Methods
We developed ULTCs for design variations of 23 NRCS practices included in PTMApp (table 1). We then used the ULTCs to develop cost functions for each practice, ultimately incorporating the functions into PTMApp.
Estimating Useful Life Total Cost
The process for developing the ULTCs and cost functions involved multiple steps (fig. 1). Creating the cost functions required identifying design variations for each practice (fig. 2). We identified variations by utilizing design parameters from the NRCS Practice Standards and Specifications (USDA 2020a; USDA 2020b) that encompassed the probable ULTC range. Each design variation has its own set of features and complexity depending on the number of design dependencies. The number of design variations ranged from one to six. We typically utilized a minimum of three design variations. A single design variation described tillage system practices such as no-till. Less complex practices having fewer design dependencies require fewer variations to bracket the ULTC range.
A wetland restoration example (NRCS Practice Code 657) illustrates the process for identifying design variations (fig. 2). The water volume from the contributing drainage area, the landscape setting and the pool creation method are all design dependencies.
 |
| Figure 1. Process for developing Useful Life Total Costs and cost functions for 23 practices. |
PTMApp is comprised of two components; i.e., a custom desktop application used to create water quality information built on ESRI Geographic Information System technology and a web application to access the information (IWI, 2020). Application uses include developing watershed plans following EPA’s nine-step process (EPA, 2008), rapidly creating Water Quality Strategies, evaluating practice opportunities at the field scale with producers, evaluating practice cost-effectiveness and tracking implementation progress. The desktop application creates GIS polygons representing possible locations for 23 practices (table 1). Attached to each polygon are physical characteristics, the estimated sediment and nutrient annual load reductions at the field edge and downstream locations, runoff volumes, cost and cost-effectiveness.
Natural Resources Conservation Service practice scenarios for Minnesota and North Dakota formed the foundation for developing the ULTCs (USDA, 2020e; 2020f) (fig. 2). A practice scenario represents a typical practice of regional, representative size under normal construction conditions with commonly used materials and equipment. The cost for the practice scenario establishes a basis for the payment rate to a landowner when implementing the practice with financial assistance through a NRCS Conservation Program.
We created a spreadsheet for each design variation, initially built from the practice scenario, for estimating the ULTC. Comparing similar practice scenarios to each design variation revealed missing features and an understanding of the cost components. We added cost components including missing steps in the implementation process and practice features for the design variation to the spreadsheet to reflect the useful life including the labor to plan, design and permit a practice; the labor for construction observation; the labor for post-construction operation and annual inspection; periodic maintenance; forgone income (as necessary) and finance cost.
The amount of labor required to plan, permit, design, bid and observe construction varies depending upon the complexity of the design and practice size. Complex practices necessitate more labor to complete each implementation step, increasing cost. For example, the labor for permitting small wetland restorations authorized by a U.S. Army Corps of Engineers nationwide permit requires only letter notification resulting in low cost.
Material quantities, as well as labor and equipment time, also increase with design complexity (i.e., more features) and practice size. We estimated design discharge by using U.S. Geological Survey regression equations derived for western and southern Minnesota (Region D) (Lorenz et al., 2009). We then sized the features of certain practices using NRCS design aids (USDA, 2020d). Sediment basin (350), filter strip (393), grade stabilization (410), grassed waterway (412), open channel (582), denitrifying bioreactor (605), and water and sediment control basin (638) features and practices were sized using design aids.
The ULTC spreadsheet included a design component. Changing a design dependency automatically updated the estimated amount of labor, construction material quantities and cost. Unit costs for construction materials, labor and quantities came from the 2020 practice scenarios for North Dakota and Minnesota (USDA, 2020e; 2020f) rather than compiling actual local unit costs from bid tabs.
 |
| Figure 2. Illustration of the process of developing variations for each practice, using a wetland restoration example. |
The amount of labor required to operate and inspect the practice on an annual basis throughout its life cycle reflects the type of practice. We developed operation and maintenance schedules for each design variation to estimate these costs. The cost of maintenance varied according to practice size, tract size, and vegetation establishment method. Maintaining native prairie for example, requires more effort than non-native grasses. Native prairie needs burning every three to five years to control noxious weeds, whereas mowing every three to five years can maintain non-native grasses.
For each year of the practice life cycle duration for land removed from production, we calculated net forgone income as the product of regional average annual yield and the commodity price for dryland soybeans using $206.54 per acre (USDA, 2020e).
We adjusted all future costs incurred throughout the life cycle duration to 2020 present value based on the following assumptions:
- planning, design and permitting occur one year preceding construction;
- construction is completed in a single year;
- operation and maintenance to ensure proper water quality performance occurs annually; and
- a finance period equal to the life cycle duration.
The life cycle duration for each practices is an important assumption when estimating the ULTC. The National Handbook of Conservation Practices provided the life cycle duration for each practice (table 1) (USDA, 2020c). Based on other sources (Tyndall and Bowman, 2016); Minnesota Department of Agriculture, 2017) including the experiences of field practitioners (Hoogendoom, personal communication, 2020; Mead, personal communication, 2020), we changed various life cycle durations to reflect actual lifespan in the field. The life cycle duration for drainage water management deviated from National Handbook of Conservation Practices (USDA, 2020c) to reflect the longevity of the water control structure and subsurface tile. Life cycle durations for practices requiring considerable planning prior to being implemented (e.g., prescribed grazing) were assumed to remain in place for multiple years.
The finance cost reflects a 2.0% interest rate for the life cycle duration. Using a discount rate of 2.0%, the ULTC represents 2020 dollars. Dividing the ULTC by the life cycle duration estimates the Annualized Useful Life Total Cost (AULTC).
Prioritize, Target, Measure Application Practice “Cost”
To estimate “cost,” PTMApp uses “unit payments” from the Minnesota or North Dakota 2020 EQIP schedule (USDA, 2020g; USDA, 2020h) as a surrogate for unit cost. Practice cost is then estimated by multiplying by the unit cost (e.g., $/surface area) and the number of units for the “primary practice.” The predominant feature for the practice (e.g., embankment) is the primary practice.
| Table 1. Practices included in the prioritize, target, measure application and the useful life total cost analysis. | |||||
|---|---|---|---|---|---|
| Practice Name | NRCS Practice No. | Practice Type | Life Cycle Duration[a] (yr) | References for Life Cycle Duration | |
| Conservation Cover | 327 | Management | 10 (5) | Minnesota Department of Agriculture, 2017 | |
| Residue and Tillage Management, No Till | 329 | Management | 1 | National Handbook of Conservation Practices UDSA, 2020c | |
| Cover Crops | 340 | Management | 1 | National Handbook of Conservation Practices UDSA, 2020c; Kentucky Energy and Environment Cabinet, 2019 | |
| Critical Area Planting[b] | 342 | Structural | 10 | National Handbook of Conservation Practices UDSA, 2020c | |
| Residue and Tillage Management, Reduced Till | 345 | Management | 1 | National Handbook of Conservation Practices UDSA, 2020c | |
| Sediment Basin | 350 | Structural | 20 | National Handbook of Conservation Practices UDSA, 2020c | |
| Pond[c] | 378 | Structural | 22.5 (20) | ||
| Riparian Herbaceous Cover | 390 | Management | 10 (5) | Professional judgment; Kentucky Energy and Environment Cabinet 2019 | |
| Riparian Forest Buffer | 391 | Management | 10 (15) | Professional judgement; Kentucky Energy and Environment Cabinet 2019 | |
| Filter Strip | 393 | Structural | 10 | National Handbook of Conservation Practices UDSA, 2020c | |
| Grade Stabilization | 410 | Structural | 15 | National Handbook of Conservation Practices UDSA, 2020c | |
| Grassed Waterway | 412 | Structural | 20 (10) | NRCS Practice Code 412 2018 operation and maintenance plan USDA, 2020a | |
| Pasture and Hay (forage/biomass planting) | 512 | Management | 10 (5) | Professional Judgment and Kentucky Energy and Environment Cabinet, 2019 | |
| Prescribed Grazing | 528 | Management | 4 (1) | ND NRCS Code 528 Practice Specification USDA, 2020a | |
| Drainage Water Management | 554 | Structural | 20 (1) | Professional judgment reflecting water control structure and installed tile | |
| Streambank and Shoreline Protection | 580 | Structural | 20 | National Handbook of Conservation Practices UDSA, 2020c | |
| Open Channel (multi-stage) | 582 | Structural | 15 | National Handbook of Conservation Practices UDSA, 2020c | |
| Nutrient Management | 590 | Management | 5 (1) | Professional judgement; assumes utilized for 5 year period once implemented | |
| Saturated Buffer | 604 | Structural | 20 (15) | Cost Sheet for Saturated Buffers Tyndall and Bowman, 2016 | |
| Denitrifying Bioreactor | 605 | Structural | 10 | National Handbook of Conservation Practices UDSA, 2020c; Tyndall and Bowman, 2016; Minnesota Department of Agriculture, 2017 | |
| Water and Sediment Control Basin | 638 | Structural | 10 | National Handbook of Conservation Practices USDA, 2020c; Kentucky Energy and Environment Cabinet, 2019 | |
| Constructed Wetland[d] | 656 | Structural | 12 (15) | National Handbook of Conservation Practices UDSA, 2020c | |
| Wetland Restoration | 657 | Structural | 15 | National Handbook of Conservation Practices UDSA, 2020c | |
[a] National Handbook of Conservation Practices (USDA, 2020c) value in parentheses when different from value used in analysis. [b] Can include grading for erosion repair. [c] Life cycle durations of 15 and 25 years for excavated pond with no principal outlet and ponds with outlets, respectively. [d] Life cycle durations of 10 and 15 years for created wetland constructed by excavation and all other methods, respectively. | |||||
Most practices, however, involve “associated practices.” Associated practices are required for proper function. The embankment for example, is the primary practice used to determine the Water and Sediment Control Basin EQIP payment. Additional practices such as an underground outlet (Practice 620) and critical area planting (Practice 342) are associated practices. The default unit costs used in PTMApp exclude the unit costs for associated practices.
We investigated the consequences of using the EQIP payment schedule for the PTMApp default unit costs. To investigate the implications, we compared the PTMApp cost to the ULTC for each practice. We estimated the PTMApp cost for each practice based on the unit payments in the EQIP schedules for North Dakota and Minnesota (USDA, 2020g; 2020h).
Useful Life Total Cost Functions
We developed cost functions for each of the 23 practices for use in water quality planning, when developing a Water Quality Strategy and incorporating them into PTMApp. To create a cost function for each practice, we changed the design dependency values in the spreadsheet for each design variation several times (figs. 1 and 2). Peak discharge, which varies with drainage area, is a common design dependency that we changed in the spreadsheet. Entering a series of drainage areas into the spreadsheet automatically updated the amount of labor, feature sizes, construction material quantities and the ULTC. The process yielded a set of estimated ULTCs based on a design dependency. The Natural Resources Conservation Service Practice Standards provided the lower, typical, and upper bounds for the design dependency (USDA, 2020a; 2020b). Generally, at least three design variations represented a practice, except for denitrifying bioreactor (1), riparian herbaceous cover (1), and filter strip (2) (table 2).
We then fit linear, exponential, logarithmic and polynomial equations to the design dependency (e.g., drainage area size) and the ULTCs. As the cost function for a practice, we selected the equation with the largest Coefficient of Determination (R2).
| Practice No./Description | Design Dependencies | No. Design Variations[a] | Useful Life Total Cost[b][c] | |||||
|---|---|---|---|---|---|---|---|---|
| Size | Units | Min. | Avg. | Max. | Max./Min. | |||
| 327 Conservation Cover | Tract size and vegetation type planted | 4 | 40-50 | Surface area (acre) | $84,394 | $110,923 | $157,711 | 1.9 |
| 329 Residue and Tillage Management, No Till[d] | Tillage method and field size | 3 | 15-100 | Surface area (acre) | $2,415 | $3,390 | $4,099 | 1.7 |
| 340 Cover Crop | Field size, termination method, vegetation type planted | 3 | 40 | Surface area (acre) | $1,961 | $2,488 | $2,984 | 1.5 |
| 342 Critical Area Planting | Tract size, intensity of grading needed, type of vegetation used | 3 | 40 | Surface area (acre) | $87,709 | $91,174 | $97,454 | 1.1 |
| 345 Residue & Tillage Management-Reduced Till[d] | Tillage method and field size | 3 | 20-200 | Surface area (acre) | $2,166 | $3,460 | $4,753 | 2.2 |
| 350 Sediment Basin | Drainage area, vegetative stabilization method, energy dissipation infiltration | 4 | 7 | Drainage area (acre) | $15,073 | $20,228 | $25,354 | 1.7 |
| 378 Pond[e] | Drainage area, energy dissipation, vegetative stabilization method | 4 | 0.6-7.8 | Surface area (acre) | $18,934 | $104,390 | $240,805 | 12.7 |
| 390 Riparian Herbaceous Cover | Vegetation type, tract size | 3 | 40 | Surface area (acre) | $81,206 | $90,715 | $103,564 | 1.3 |
| 391 Riparian Forest Buffer | Vegetation type, tract size | 2 | 40 | Surface area (acre) | $127,072 | $178,087 | $229,102 | 1.8 |
| 393 Filter Strip | Vegetation type, filter strip width–drainage area ratio | 2 | 0.15-0.37 | Surface area (acre) | $1,837 | $2,580 | $3,323 | 1.8 |
| 410 Grade Stabilization | Drainage area, watershed slope, check structure type | 4 | 9-320 | Drainage area (acre) | $11,320 | $31,895 | $54,177 | 4.8 |
| 412 Grassed Waterway | Drainage area, watershed slope, need for check structures, vegetation establishment | 6 | 200-640 | Drainage area (acre) | $13,231 | $20,375 | $28,320 | 2.1 |
| 512 Pasture and Hay (Forage/Biomass Planting) | Vegetation type, tract size | 3 | 80-120 | Surface area (acre) | $34,312 | $53,517 | $79,023 | 2.3 |
| 528 Prescribed Grazing | Vegetation type, tract size, no. of animal units | 3 | 160-1,200 | Grazing area (acre) | $4,325 | $49,572 | $132,599 | 30.7 |
| 554 Drainage Water Management | Watershed slope (no. of control structures) | 3 | 10 | Drainage area (acre) | $15,305 | $17,859 | $22,396 | 1.5 |
| 580 Streambank and Shoreline Protection | Bank height and slope | 3 | 300-500 | Length* height (ft) | $9,932 | $20,397 | $31,392 | 3.1 |
| 582 Open Channel (Multi-stage) | Drainage area (size of base flow and second stage channel) | 3 | 1-10 | Drainage area (mi2) | $16,497 | $22,877 | $30,487 | 1.8 |
| 590 Nutrient Management | Fertilizer application method and field size | 2 | 40 | Surface area (acre) | $3,479 | $4,655 | $5,830 | 1.7 |
| 604 Saturated Buffer | Drainage area (length of pipe), type of vegetation management | 3 | 20 | Drainage area (acre) | $9,833 | $11,735 | $14,124 | 1.4 |
| 605 Denitrifying Bioreactor | Drainage area size (bioreactor volume) | 1 | 10 | Drainage area (acre) | $29,202 | |||
| 638 Water and Sediment Control Basin | Drainage area, watershed slope, runoff volume, farmed or not farmed, vegetation type | 6 | 1-40 | Drainage area (acre) | $10,000 | $17,328 | $34,636 | 3.5 |
| 656 Constructed Wetland | Drainage area, construction method, vegetation type | 5 | 0.5-40 | Surface area (acre) | $8,645 | $116,543 | $257,743 | 29.8 |
| 657 Wetland Restoration | Drainage area, construction method, vegetation type | 6 | 1-30 | Surface area (acre) | $11,586 | $50,038 | $90,090 | 7.8 |
| [a] Number of design variations used to derive ULTC statistics. [b] Useful life total cost includes planning, permitting, design, construction, operation, maintenance, financing and forgone income. [c] Using discount rate of 2% and finance cost of 2% per year. [d] Data for Practice Code 329 is for no till. Data for Practice Code 345 is reduced till. [e] Pond values are surface area. Surface area of 0.6 and 7.8 acres correspond to product of storage and effective height of 3.6 and 2,945 acre-ft2, respectively. | ||||||||
| Table 2. Summary of Useful Life Total Costs (2020 present value) for 23 practices estimated using the design variation spreadsheets. | ||||||||
Results and Discussion
The Water Quality Strategy is a tool to guide implementation and ensure attaining the water quality goals is commensurate with the amount of (usually) public money needed. The number of practices in a Water Quality Strategy can easily approach or exceed one hundred. Using a single value to represent the cost of a practice results in an unintentional misrepresentation of the amount of money required to implement not only the practice, but also successfully execute the Water Quality Strategy. The ULTCs and AULTCs exhibit a large range for the 23 practices (tables 2 and 3). The maximum to minimum ratios for the ULTCs are 1.1 to 30.7. If the primary practice's cost is non-normally distributed, using a mean value poorly represents the cost.
- the number of features comprising a practice differs among the multiple design variations;
- the same practice can be used across a large range of drainage area sizes leading to a range of designs and feature sizes;
- some costs are fixed (e.g., mobilization) regardless of practice size;
- the amount of labor to plan, permit and design a practice depends on practice complexity;
- construction cost increases with practice complexity and size; and
- the amount of land removed from production varies.
The ULTCs and AULTCs show large ranges because:
Normalizing the AULTCs by their respective number of units produces unit AULTCs (table 4). Multiplying a minimum, typical or maximum AULTC unit value by the number of units for the design dependency estimates the ULTC.
| Table 3. Summary of Annual Useful Life Total Cost (2020 present value) for 23 practices estimated using the design variation spreadsheets. | |||||||||
| Practice No./Description | No. Design Variations[a] | Life Cycle Duration (yrs) | Size | Units | Annual Useful Life Total Cost ($/yr)[b][c] | ||||
| Min. | Avg. | Max. | |||||||
| 327 Conservation Cover | 4 | 10 | 40-50 | Surface area (acre) | $8,439 | $11,092 | $15,771 | ||
| 329 Residue and Tillage Management, No Till[d] | 3 | 1 | 15-100 | Surface area (acre) | $2,415 | $3,390 | $4,099 | ||
| 340 Cover Crop | 3 | 1 | 40 | Surface area (acre) | $1,961 | $2,488 | $2,984 | ||
| 342 Critical Area Planting | 3 | 10 | 40 | Surface area (acre) | $8,771 | $9,117 | $9,745 | ||
| 345 Residue & Tillage Management–Reduced Till[d] | 3 | 1 | 20-200 | Surface area (acre) | $2,166 | $3,460 | $4,753 | ||
| 350 Sediment Basin | 4 | 20 | 7 | Drainage area (acre) | $754 | $1,011 | $1,268 | ||
| 378 Pond[e] | 4 | 22.5 | 0.6-7.8 | Surface area (acre) | $1,262 | $4,302 | $9,632 | ||
| 390 Riparian Herbaceous Cover | 3 | 10 | 40 | Surface area (acer) | $8,121 | $9,071 | $10,356 | ||
| 391 Riparian Forest Buffer | 2 | 10 | 40 | Surface area (acre) | $12,707 | $17,809 | $22,910 | ||
| 393 Filter Strip | 2 | 10 | 0.15-0.37 | Surface area (acre) | $184 | $258 | $332 | ||
| 410 Grade Stabilization | 4 | 15 | 9-320 | Drainage area (acre) | $755 | $2,126 | $3,612 | ||
| 412 Grassed Waterway | 6 | 20 | 200-640 | Drainage area (acre) | $662 | $1,019 | $1,416 | ||
| 512 Pasture and Hay (forage/biomass planting) | 3 | 10 | 80-120 | Surface area (acre) | $3,431 | $5,352 | $7,902 | ||
| 528 Prescribed Grazing | 3 | 4 | 160-1,200 | Grazing area (acre) | $1,081 | $12,393 | $33,150 | ||
| 554 Drainage Water Management | 3 | 20 | 10 | Drainage area (acre) | $765 | $893 | $1,120 | ||
| 580 Streambank and Shoreline Protection | 3 | 20 | 300-500 | Length × height (ft) | $497 | $1,020 | $1.570 | ||
| 582 Open Channel (multi-stage ditch) | 3 | 15 | 1-10 | Drainage area (mi2) | $1,100 | $1,525 | $2,032 | ||
| 590 Nutrient Management | 2 | 5 | 40 | Surface area (acre) | $696 | $931 | $1,166 | ||
| 604 Saturated Buffer | 3 | 20 | 20 | Drainage area (acre) | $492 | $587 | $706 | ||
| 605 Denitrifying Bioreactor | 1 | 10 | 10 | Drainage area (acre) | $2,920 | ||||
| 638 Water and Sediment Control Basin | 6 | 10 | 40-50 | Drainage area (acre) | $1,000 | $1,733 | $3,464 | ||
| 656 Constructed Wetland[e] | 5 | 12 | 15-100 | Surface area (acre) | $865 | $8,259 | $17,183 | ||
| 657 Wetland Restoration | 6 | 15 | 40 | Surface area (acre) | $772 | $3,336 | $6,006 | ||
[a] Number of design variations used to derive cost statistics. [b] Annual useful life total cost includes planning, permitting, design, construction, operation, maintenance, financing and forgone income. Uses discount rate of 2% and finance cost of 2% per year. [c] Useful life total cost estimate (2020 PV) from table 2 divided by the useful life duration. [d] No till for Practice Code 329. Reduced till for Practice Code 345. [e] Life cycle duration varies for practice, depending upon design and construction methods. | |||||||||
| Table 4. Summary of Annual Useful Life Costs (2020 present value) per design dependency unit for 23 practices. | ||||||
| Life Cycle Duration (yrs) | Annual Useful Life Cost Per Unit[a][b] | |||||
| Practice No./Description | Min. | Avg. | Max. | Max./Min. | Design Dependency Units | |
| 327 Conservation Cover | 10 | $211 | $258 | $315 | 1.5 | Acre planted |
| 329 Residue and Tillage Management, No Till[c] | 1 | $24 | $111 | $273 | 11.4 | Acre of field |
| 340 Cover Crop | 1 | $49 | $62 | $75 | 1.5 | Acre planted |
| 342 Critical Area Planting | 10 | $219 | $228 | $244 | 1.1 | Acre planted |
| 345 Residue & Tillage Management–Reduced Till[c] | 1 | $17 | $92 | $238 | 14 | Acre of field |
| 350 Sediment Basin | 20 | $108 | $144 | $181 | 1.7 | Acre of contributing drainage area |
| 378 Pond[d] | 22.5 | $863 | $1,300 | $2,104 | 2.4 | Acre of contributing drainage area |
| 390 Riparian Herbaceous Cover | 10 | $203 | $227 | $259 | 2.5 | Acre planted |
| 391 Riparian Forest Buffer | 10 | $318 | $445 | $573 | 2.6 | Acre planted |
| 393 Filter Strip | 10 | $37 | $58 | $80 | 2.2 | Acre planted |
| 410 Grade Stabilization | 15 | $11 | $37 | $84 | 7.6 | Acre of contributing drainage area |
| 412 Grassed Waterway | 20 | $2.16 | $2.88 | $3.44 | 1.6 | Acre of contributing drainage area |
| 512 Pasture and Hay (forage/biomass planting) | 10 | $43 | $56 | $66 | 1.5 | Acre planted |
| 528 Prescribed Grazing | 4 | $3 | $12 | $28 | 9.3 | Acre grazed |
| 554 Drainage Water Management | 20 | $77 | $89 | $112 | 1.5 | Acre of contributing drainage area |
| 580 Streambank and Shoreline Protection | 20 | $153 | $473 | $1,060 | 3.1 | Product of bank height and length |
| 582 Open Channel (Multi-stage) | 15 | $203 | $531 | $1,100 | 5.4 | Acre of contributing drainage area |
| 590 Nutrient Management | 5 | $17 | $23 | $29 | 142.2 | Acre of field |
| 604 Saturated Buffer | 20 | $25 | $29 | $35 | 1.4 | Acre of contributing drainage area |
| 605 Denitrifying Bioreactor[e] | 10 | $292 | Acre of contributing drainage area | |||
| 638 Water and Sediment Control Basin | 10 | $240 | $373 | $577 | 6 | Acre of contributing drainage area |
| 656 Constructed Wetland[d] | 12 | $419 | $4,473 | $17,290 | 41.3 | Acre constructed |
| 657 Wetland Restoration | 15 | $114 | $469 | $901 | 7.9 | Acre restored |
[a] Annual useful life cost per unit includes planning, permitting, design, construction, operation, maintenance, financing and forgone income. [b] Annual cost from table 3 adjusted for the number of units used to derive the cost estimate. The number of units may vary for the same practice. [c] No till for Practice Code 329. Reduced till for Practice Code 345. [d] Life cycle duration varies for practice, depending upon design and construction methods. [e] No design variation for this practice. | ||||||
Legacy PTMApp costs based on the EQIP payment schedule range from 33% to 151% of the ULTC construction and materials (table 5). The average percentage is 61%. The percentage compares favorably to the EQIP payment rate based on 75% of the estimated construction costs for a typical implementation scenario.
| Table 5. Summary of Useful Life Total Cost comparison to legacy PTMApp “cost” by project development category. | ||||||||||
| Project Development Category – Average Percentage of Useful Life Total Cost | ||||||||||
| Practice No./Description | Avg. ULTC (2020 Present Value) | Planning (%) | Permitting (%) | Const. Plans & Specs (%) | Construction & Materials (%) | Forgone Income (%) | O & M (%) | Financing (%) | PTMApp (% of ULTC) | Ratio of Legacy PTMApp Cost to ULTC Construction and Materials (%) |
| 327 Conservation Cover | $110,923 | 1.3 | 0.0 | 0.0 | 16.3 | 75.1 | 5.9 | 1.3 | 12 | 74 |
| 329 Residue and Tillage Management, No Till | $3,390 | 7.4 | 0.0 | 0.0 | 92.6 | 0.0 | 0.0 | 0.0 | 55 | 59 |
| 340 Cover Crop | $2,488 | 5.6 | 0.0 | 0.0 | 94.4 | 0.0 | 0.0 | 0.0 | 48 | 51 |
| 342 Critical Area Planting | $91,174 | 0.5 | 0.0 | 0.1 | 10.6 | 82.5 | 5.4 | 0.9 | 16 | 151 |
| 345 Residue & Tillage Management–Reduced Till | $3,460 | 9.8 | 0.0 | 0.0 | 90.2 | 0.0 | 0.0 | 0.0 | 54 | 60 |
| 350 Sediment Basin | $20,228 | 7.7 | 6.4 | 5.6 | 52.1 | 7.1 | 12.7 | 8.5 | 22 | 42 |
| 378 Pond | $104,390 | 4.0 | 3.2 | 4.1 | 54.5 | 14.0 | 10.0 | 10.1 | 31 | 57 |
| 390 Riparian Herbaceous Cover | $90,715 | 1.3 | 0.0 | 0.0 | 8.2 | 83.4 | 6.4 | 0.7 | 6 | 73 |
| 391 Riparian Forest Buffer | $178,087 | 1.2 | 0.0 | 0.0 | 43.3 | 47.7 | 4.3 | 3.6 | 40 | 92 |
| 393 Filter Strip | $2,580 | 19.5 | 0.0 | 0.0 | 0.7 | 9.5 | 69.8 | 0.4 | 1 | 142 |
| 410 Grade Stabilization | $31,895 | 6.4 | 5.2 | 4.5 | 55.1 | 3.0 | 19.0 | 6.9 | 32 | 58 |
| 412 Grassed Waterway | $20,375 | 7.2 | 5.4 | 4.8 | 34.9 | 30.4 | 11.5 | 5.7 | 27 | 77 |
| 512 Pasture and Hay (Forage/Biomass Planting) | $53,517 | 6.1 | 0.0 | 0.0 | 25.4 | 54.1 | 12.4 | 2.1 | 16 | 63 |
| 528 Prescribed Grazing | $49,572 | 4.4 | 0.0 | 0.0 | 46.4 | 32.8 | 15.1 | 1.4 | 50 | 108 |
| 554 Drainage Water Management | $17,859 | 22.6 | 3.2 | 6.6 | 34.1 | 9.2 | 18.7 | 5.6 | 21 | 62 |
| 580 Streambank and Shoreline Protection | $60,838 | 10.1 | 8.2 | 7.7 | 42.8 | 2.7 | 21.6 | 7.0 | 24 | 56 |
| 582 Open Channel (Multi-stage) | $22,877 | 9.1 | 7.2 | 9.0 | 35.9 | 21.1 | 13.2 | 4.5 | 30 | 84 |
| 590 Nutrient Management | $5,236 | 16.0 | 0.0 | 0.0 | 30.8 | 0.0 | 52.1 | 1.0 | 20 | 65 |
| 604 Saturated Buffer | $11,735 | 14.3 | 5.4 | 9.5 | 27.2 | 4.0 | 35.0 | 4.4 | 15 | 55 |
| 605 Denitrifying Bioreactor | Only one design variation | |||||||||
| 638 Water and Sediment Control Basin | $17,328 | 14.8 | 5.1 | 7.4 | 53.7 | 8.6 | 5.9 | 4.4 | 22 | 41 |
| 656 Constructed Wetland | $116,543 | 6.1 | 5.8 | 5.5 | 51.5 | 10.8 | 14.8 | 5.5 | 17 | 33 |
| 657 Wetland Restoration | $50,038 | 5.4 | 6.1 | 4.4 | 41.0 | 25.5 | 12.0 | 5.6 | 19 | 46 |
| Average Percentage | 8.2 | 2.8 | 3.1 | 42.8 | 23.7 | 15.7 | 3.6 | 26 | 61 | |
Some landowners may be hesitant to implement practices because they are responsible for maintaining them without fully understanding their cost obligation. The operation and maintenance component for many practices tends to be less than 15% of the ULTC, but can be a considerable amount (table 5).
| Table 6. Useful Life Total Costs[a] estimated using the ULTC cost functions and number of design dependency units. | ||||||||||
| Minimum | Mid-Range | Maximum | Design Dependency | |||||||
| Practice No./Description | No. of Units | ULTC | No. of Units | ULTC | No. of Units | ULTC | ||||
| 327 Conservation Cover | 1 | $4,037 | 81 | $17,673 | 160 | $317,365 | Acres planted | |||
| 329 Residue and Tillage Management, No Till[b] | 5 | $236 | 323 | $8,906 | 640 | $16,157 | Acres of field | |||
| 340 Cover Crop | 5 | $627 | 323 | $18,656 | 640 | $32,550 | Acres planted | |||
| 342 Critical Area Planting | 1 | 4,055 | 81 | $169,171 | 160 | $301,523 | Acres planted | |||
| 345 Residue & Tillage Management, Reduced Till[b] | 5 | $192 | 323 | $6,486 | 640 | $11,551 | Acres of field | |||
| 350 Sediment Basin | 5 | $16,863 | 23 | $36,167 | 40 | $47,695 | Acres of contributing drainage area | |||
| 378 Pond | 1 | $26,803 | 26 | $269,937 | 50 | $354,320 | Acres of contributing drainage area | |||
| 390 Riparian Herbaceous Cover | 1 | $3,589 | 321 | $635,853 | 640 | $1,180,770 | Acres planted | |||
| 391 Riparian Forest Buffer | 1 | $3,443 | 321 | $997,217 | 640 | $1,962,456 | Acres planted | |||
| 393 Filter Strip | 0.69 | $2,305 | 26 | $2,866 | 50 | $2,981 | Acres planted | |||
| 410 Grade Stabilization | 5 | $9,669 | 163 | $28,180 | 320 | $34,664 | Acres of contributing drainage area | |||
| 412 Grassed Waterway | 20 | $12,015 | 330 | $16,144 | 640 | $20,274 | Acres of contributing drainage area | |||
| 512 Pasture and Hay (Forage/Biomass Planting) | 1 | $2,355 | 81 | $42,811 | 160 | $67,092 | Acres planted | |||
| 528 Prescribed Grazing | 5 | $1,324 | 603 | $23,406 | 1200 | $7,634 | Acres grazed | |||
| 554 Drainage Water Management | 10 | $13,408 | 75 | $11,833 | 140 | $11,384 | Acres of contributing drainage area | |||
| 580 Streambank & Shoreline Protection | 250 | $9,521 | 4492 | $107,265 | 20000 | $803,559 | Product of bank height and length | |||
| 582 Open Channel (Multi-stage) | 640 | $15,676 | 3520 | $24,212 | 6400 | $28,199 | Acres of contributing drainage area | |||
| 590 Nutrient Management | 10 | $6,741 | 646 | $27,808 | 1280 | $35,087 | Acres of field | |||
| 604 Saturated Buffer | 5 | $11,607 | 53 | $17,231 | 100 | $36,126 | Acres of contributing drainage area | |||
| 605 Denitrifying Bioreactor | 5 | $14,250 | 53 | $27,268 | 100 | $40,015 | Acres of contributing drainage area | |||
| 638 Water and Sediment Control Basin | 1 | $8,419 | 21 | $15,006 | 40 | $25,984 | Acres of contributing drainage area | |||
| 656 Constructed Wetland | 0.046 | $5,578 | 21 | $134,717 | 40 | $188,338 | Acres constructed | |||
| 657 Wetland Restoration | 1 | $15,767 | 11 | $48,199 | 20 | $63,684 | Acres restored | |||
[a] Useful life cost per unit includes planning, permitting, design, construction, operation, maintenance, financing and forgone income. Values are averages for all design variations; 2020 values. [b] No till for Practice Code 329. Reduced till for Practice Code 345. | ||||||||||
We estimated the ULTC range using the minimum, mid-range and maximum number of design units (table 6) using the cost functions (table 7). The number of design units varies considerably for each practice. The minimum number of design units represents the smallest practical practice size. The maximum number of units, based on the NRCS’s Practice Standards and Specifications (USDA, 2020a; USDA, 2020b), represents the largest technically feasible practice size. The mid-range number of design units represents a typical value for the practice. These UTLCs are useful for screening practice cost estimates; practice costs should generally be within the range. The ULTC for Riparian Herbaceous and Forest Buffer seem exceptionally large. The large number of acres and forgone income drive the ULTCs for these practices.
| Table 7. Useful life total cost functions for 23 agricultural practices. | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Practice No. | No. of Points Used to Derive Function | Function | Units | R2 | ||||||
| Minimum | Maximum | |||||||||
| Practice Name | Units | Cost | Units | Cost | ||||||
| Conservation Cover | 327 | 15 | = (4036.6*Surf. Area^-0.14)*Surf. Area | Acres | 0.66 | 1 | $4,037 | 160 | $317,365 | |
| Residue and Tillage Management, No Till | 329 | 10 | = (58.102*Surf. Area^-0.129)*Surf. Area | Acres | 0.56 | 5 | $236 | 640 | $16,157 | |
| Cover Crop[a] | 340 | 24 | = (110.39*Surf. Area^-0.134)*Surf. Area | Acres | 0.40 | 5 | $627 | 640 | $32,550 | |
| Critical Area Planting | 342 | 15 | = (4055.3*Surf. Area^-0.151)*Surf. Area | Acres | 0.72 | 1 | $4,055 | 160 | $301,523 | |
| Residue & Tillage Management – Reduced Till | 345 | 5 | = (49.454*Surf. Area^-0.156)*Surf. Area | Acres | 0.92 | 5 | $192 | 640 | $11,551 | |
| Sediment Basin with & without Infiltration | 350 | 20 | = (7541.3*(Drainage Area)^-0.5)*Drainage Area | Acres | 0.79 | 5 | $16,863 | 40 | $47,695 | |
| Pond | 378 | 14 | = (-5040*ln(Surf. Area)+ 26803)*Surf. Area | Acres | 0.57 | 1 | $26,803 | 50 | $354,320 | |
| Riparian Herbaceous Cover | 390 | 27 | = (3589.4*Surf. Area^-0.103)*Surf. Area | Acres | 0.60 | 1 | $3,598 | 640 | $1,180,770 | |
| Riparian Forest Buffer | 391 | 18 | = (-5.834*ln(Surf. Area)+ 3443.3)*Surf. Area | Acres | 0.01 | 1 | $3,443 | 640 | $1,962,456 | |
| Filter Strip | 393 | 32 | = (2357*(Drainage Area)^-0.94))* (Drainage Area)) | Acres | 0.93 | 0.69 | $2,305 | 50 | $2,981 | |
| Grade Stabilization | 410 | 9 | = (5899.2*^-0.693)*Drainage Area | Acres | 0.76 | 5 | $9.669 | 320 | $34,664 | |
| Grassed Waterway | 412 | 35 | = (0.0111*Drainage Area/43560+9.7906)*Length | Acres/ft | 0.34 | 20 | $12,015 | 640 | $20,274 | |
| Pasture and Hay (Forage/Biomass Planting) | 512 | 15 | = (2354.8*Surf. Area^-0.34)*Surf. Area | Acres | 0.80 | 1 | $2,355 | 160 | $67,092 | |
| Prescribed Grazing | 528 | 21 | = (-47.16*ln(Grazing Area)+340.73)* Grazing Area | Acres | 0.54 | 5 | $1,324 | 1200 | $7,634 | |
| Drainage Water Management[b] | 554 | 16 | = (29145*(Drainage Area)^-1.202)* (Drainage Area) | Acres | 0.99 | 10 | $18,305 | 140 | $10,741 | |
| Streambank and Shoreline Protection[c] | 580 | 44 | =24.22*(bank ht*length) -1524 | Feet | 0.72 | 250 | $9,521 | 20000 | $803,599 | |
| Open Channel (Multi-stage) | 582 | 4 | = (3017.6*(Drainage Area)^-0.745) *Drainage Area | Acres | 0.99 | 640 | $15.676 | 6400 | $28,199 | |
| Nutrient Management | 590 | 10 | = (1949.9*Field Area^-0.66)*Field Area | Acres | 0.78 | 5 | $3,370 | 640 | $17,543 | |
| Saturated Buffer | 604 | 10 | = 2.9985*(Drainage Area)^2-56.754 *(Drainage Area)+11816 | Acres | 0.59 | 5 | $11,607 | 100 | $36,126 | |
| Denitrifying Bioreactor | 605 | 11 | = 271.21*(Drainage Area)+12894 | Acres | 0.99 | 5 | $14,250 | 100 | $40,015 | |
| Water and Sediment Control Basin | 638 | 6 | = 8179.3*2.718^(0.0289*(Drainage Area)) | Acres | 0.99 | 1 | $8,419 | 40 | $25,984 | |
| Constructed Wetland | 656 | 16 | = (27661*Surf. Area^-0.48)*Surf. Area | Acres | 0.95 | 0.046 | $5.578 | 40 | $188,338 | |
| Wetland Restoration | 657 | 17 | = (15767*Surf. Area^-0.534)*Surf. Area | Acres | 0.80 | 1 | $15,767 | 20 | $63,684 | |
[a] Rye-grass with and without termination. [b] Cost increases for smaller drainage areas with increasing water slope, because multiple structures are necessary. [c] Units for Streambank and Shoreline Protection are $ per foot. Design for rock rip-rap toe stabilization and bioengineered only (no gabions). | ||||||||||
The ULTC cost functions for the practices revealed a number of mathematical relationships (table 7). The number of points used to derive the cost functions (combination of design variations and design dependencies) ranged from four to forty-four (table 7) and varied depending on the form of the mathematical relationship. Linear relationships required fewer points to describe the best-fit line to represent the cost function than exponential relationships.
Useful life total cost functions typically vary either linearly or exponentially with size of the contributing drainage area (fig. 3). Some cost functions differ markedly depending on design. The cost function for Water and Sediment Control Basins is “well behaved” (fig. 3a). The Coefficient of Determination is large and the points representing the ULTCs deviate slightly from the fitted line. The cost function for cover crops (fig. 3d) behaves well, but clearly demonstrates the effect of design variation; i.e., types of plants utilized and termination method. The cost function for grassed waterways depends on drainage area size and behaves poorly exhibiting a low Coefficient of Determination (fig. 4a). Predictability improves by creating a cost function dependent upon two design dependencies; drainage area and watershed slope (fig. 4b). Watershed slope being included in the cost function as a design dependency reflects a change in the channel size and need for check structures to avoid critical flow.
Low R2 values for cover crops (fig. 3d), grassed waterways (fig. 4), riparian forest buffer (fig. 5a) and streambank and shoreline protection (fig. 5b) result from combining multiple design variations into a single cost function for use within PTMApp. Creating cost functions for these practices based on multiple design dependencies would improve predictability. However, the cost estimation process within PTMApp currently allows only for a single design dependency.
 Figure 3. Example Useful Life Total Cost functions (2020 dollars) for four common practices. Each point represents a Useful Life Total Cost used to derive the function. |
 Figure 4. Example cost functions (2020 dollars) for grassed waterways. Each point represents a Useful Life Total Cost used to create the function. |
Conclusions
The ULTCs (table 2) and AULTC costs (tables 3 and 4) represent the total cost for implementing a practice. Because cost functions incorporate the combined influence of landscape setting and design complexity, an estimate of practice cost computed using a cost function (table 7) is more accurate than using a typical (average) value or EQIP unit payment. When developing a Water Quality Strategy to achieve water quality goals and realize the anticipated societal benefits, using the cost functions provides an accurate estimate of the total cost borne by society. The ULTCS, AULTCs, and cost functions have general utility for water quality planning and field scale implementation.
 |
| Figure 5. Cost functions (2020 dollars) for riparian forest buffer and streambank and shoreline protection. Each point represents a Useful Life Total Cost used to create the function. |
The ULTCs and AULTCs are appropriate for use regionally within the upper Midwest and elsewhere for water quality planning and practice implementation, provided the unit costs are representative of the area. The ULTC spreadsheet created for each practice design variation is extremely useful; it is simple to update the unit costs for labor and construction materials for other locations. Spreadsheet use as a cost-estimating tool necessitates updating quantities and unit costs on a regular basis as the practice design progresses. The process for developing ULTCs and the spreadsheets could be adapted for urban applications.
Because of considerable design variation, the cost functions for some practices exhibit poor predictability. Certain practices like cover crops (fig. 3d), grassed waterways (fig. 4), riparian forest buffer (fig. 5a) and streambank and shoreline protection (fig. 5b) with several very different designs are poorly described by a single cost function. Developing cost functions that separate design dependencies improves predictability (fig. 5).
This research’s ULTCs and AULTCs are useful in a variety of ways. A practice cost is calculated by multiplying the AULTC unit cost (table 4) by the number of units required for the design dependency (e.g., surface area). The average AULTC (table 4) represents the practice’s central tendency value. Cost sensitivity analysis can utilize the range of AULTCs. The ULTCs (table 6) are useful for quickly estimating practice costs during planning and evaluating the accuracy of practice cost estimates. By programming the cost functions (table 7) into a spreadsheet they can be applied to the practices comprising a Water Quality Strategy to rapidly develop an estimated of the total implementation cost.
The continuous cost functions resulting from this applied research and incorporated into PTMApp improve the technology available to Water Quality Practitioners for completing planning and rapid development of Water Quality Strategies. The process used by PTMApp to estimate cost uses a single design dependency. To improve ULTC predictability, we recommend modifying the process used to account for multiple design dependencies.
Non-engineers and non-scientists frequently use PTMApp to generate water quality data, but rarely take the time to understand what the cost value means. PTMApp utilizes both the ULTC and a “default” value for estimating practice cost, cost-effectiveness and the amount of a Water Quality Strategy. Currently, the default values are a single EQIP payment for the primary practice. If the user intends to estimate the potential federal cost share amount of a Water Quality Strategy, we recommend updating the legacy PTMApp EQIP payment values to reflect the most recent schedule for the primary and all associated practices.
Engineers and scientists should include a cost definition in their Water Quality Strategy. Clearly describing the cost components ensures proper use of the cost value, which includes requesting an adequate amount of money for implementation and realizing the societal benefit of improved water quality.
Acknowledgements
The North Dakota Department of Environmental Quality supported this applied research through a Clean Water Section 319 grant. We appreciate the guidance provided by Mr. Greg Sandness, Department of Environmental Quality Section 319 Coordinator.
References
Arabi, M., Govindaraju, R. S., & Hantush, M. M. (2006). Cost-effective allocation of watershed management practices using a genetic algorithm. Water Resour. Res., 42, W10429. https://doi.org/10.1029/2006WR004931
Board of Water and Soil Resources (BWSR). (2021). Prioritize, target, measure application (PTMApp) desktop ArcGIS pro toolbar user’s guide. 90. Retrieved from state.mn.us
Bracmort, K. S., Lee, J. G., Engel, B. A., & Frankenberger, J. R. (2004). Estimating the long-term benefits and costs of BMPs in an agricultural watershed. Paper No: 042174. Proc. 2004 ASAE/CSAE Annual International Meeting. Retrieved from http://www.nurserycropscience.info/water/managing-runoff/other-references/bracmort-2004-estimate-long-term-benef-of-bmps.pdf
Christianson, L., Tyndall, J., & Helmers, M. (2013). Financial comparison of seven nitrate reduction strategies for Midwestern agricultural drainage. Water Resour. Econ., 2-3, 30-56. https://doi.org/10.1016/j.wre.2013.09.001
EPA. (2008). Handbook for developing watershed plans to restore and protect our waters. EPA 841-B-08-002. Retrieved from https://www.epa.gov/nps/handbook-developing-watershed-plans-restore-and-protect-our-waters
Fox, R. J., Fisher, T. R., Gustafson, A. B., Koontz, E. L., Lepori-Bui, M., Kvalnes, K. L.,... Silaphone, K. (2021). An evaluation of the Chesapeake Bay management strategy to improve water quality in small agricultural watersheds. J. Environ. Manage., 299, 113478. https://doi.org/10.1016/j.jenvman.2021.113478
Gitau, M. W., Veith, T. L., Gburek, W. J., & Jarrett, A. R. (2006). Watershed level best management practice selection and placement in the Town Brook Watershed, New York. JAWRA J. Am. Water Resour. Assoc., 42(6), 1565-1581. https://doi.org/10.1111/j.1752-1688.2006.tb06021.x
International Water Institute. (2020). Prioritize, Target, Measure Application. Retrieved from https://nd.ptmapp.iwinst.org/
Kaini, P., Artita, K., & Nicklow, J. W. (2012). Optimizing structural best management practices using SWAT and genetic algorithm to improve water quality goals. Water Resour. Manage., 26(7), 1827-1845. https://doi.org/10.1007/s11269-012-9989-0
Kalcic, M. M., Frankenberger, J., & Chaubey, I. (2015). Spatial optimization of six conservation practices using SWAT in tile-drained agricultural watersheds. JAWRA J. Am. Water Resour. Assoc., 51(4), 956-972. https://doi.org/10.1111/1752-1688.12338
Kaufman, D. E., Shenk, G. W., Bhatt, G., Asplen, K. W., Devereux, O. H., Rigelman, J. R.,... Ball, W. P. (2021). Supporting cost-effective watershed management strategies for Chesapeake Bay using a modeling and optimization framework. Environ. Model. Softw., 144, 105141. https://doi.org/10.1016/j.envsoft.2021.105141
Kentucky Energy and Environment Cabinet. (2019). Soil and water quality cost share practice handbook. 29. Retrieved from https://eec.ky.gov/Natural-Resources/Conservation/State%20Cost%20Share%20Documents/2019%20Kentucky%20Soil%20Water%20State%20Cost%20Share%20Handbook.doc
Liu, Y., Wang, R., Guo, T., Engel, B. A., Flanagan, D. C., Lee, J. G., Wallace, C. W. (2019). Evaluating efficiencies and cost-effectiveness of best management practices in improving agricultural water quality using integrated SWAT and cost evaluation tool. J. Hydrol., 577, 123965. https://doi.org/10.1016/j.jhydrol.2019.123965
Lorenz, D. L., Sanocki, C. A., & Kocian, M. J. (2009). Techniques for estimating the magnitude and frequency of peak flows on small streams in Minnesota based on data through water year 2005: Scientific Investigations Report. USGS Scientific Investigations Report 2009-5250. https://doi.org/10.3133/sir20095250
Minnesota Department of Agriculture. (2017). Agricultural BMP Handbook for Minnesota 2017. 262. Retrieved from https://bbe.umn.edu/sites/bbe.umn.edu/files/agricultural-best-management-practices-handbook-for-minnesota-second-edition.pdf
Price, E., Flemming, T., & Wainger, L. (2021). Cost analysis of stormwater and agricultural practices for reducing nitrogen and phosphorus runoff in Maryland. Report number: TS-772-21. University of Maryland Center for Environmental Science. https://doi.org/10.13140/RG.2.2.28896.74246/1
Srivastava, P., Hamlett, J. M., Robillard, P. D., & Day, R. L. (2002). Watershed optimization of best management practices using AnnAGNPS and a genetic algorithm. Water Resour. Res., 38(3). https://doi.org/10.1029/2001WR000365
Tyndall, J., & Bowman, T. (2016). Iowa Nutrient Reduction Strategy Best Management Practice cost over series. Department of Ecology and Natural Resource Management. Iowa State University. Retrieved from https://www.nrem.iastate.edu/bmpcosttools/
USDA Natural Resources Conservation Service. (2020h). EQIP payment schedules for Minnesota. Retrieved from https://www.nrcs.usda.gov/wps/PA_NRCSConsumption/download?cid=nrcseprd1414607&ext=pdf
USDA Natural Resources Conservation Service. (2020g). EQIP payment schedules for North Dakota. Retrieved from https://www.nrcs.usda.gov/wps/PA_NRCSConsumption/download?cid=nrcseprd1414607&ext=pdf
USDA Natural Resources Conservation Service. (2020b). Field office technical guide for Minnesota. United States Department of Agriculture. Retrieved from https://www.nrcs.usda.gov/wps/portal/nrcs/main/national/technical/fotg/
USDA Natural Resources Conservation Service. (2020a). Field office technical guide for North Dakota. United States Department of Agriculture. Retrieved from https://www.nrcs.usda.gov/wps/portal/nrcs/main/national/technical/fotg/
USDA Natural Resources Conservation Service. (2020f). Minnesota practice scenarios for fiscal year 2020. Retrieved from https://www.nrcs.usda.gov/wps/PA_NRCSConsumption/download?cid=nrcseprd1534427&ext=pdf
USDA Natural Resources Conservation Service. (2020d). Minnesota: Design tools. Retrieved from https://www.nrcs.usda.gov/wps/portal/nrcs/mn/technical/engineering/NRCSEPRD1303662
USDA Natural Resources Conservation Service. (2020c). National handbook of conservation practices. Retrieved from https://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=45702.wba
USDA Natural Resources Conservation Service. (2020e). North Dakota practice scenarios for fiscal year 2020.
Veith, T. L., Wolfe, M. L., & Heatwole, C. D. (2003). Optimization procedure for cost effective BMP placement at a watershed scale. JAWRA J. Am. Water Resour. Assoc., 39(6), 1331-1343. https://doi.org/10.1111/j.1752-1688.2003.tb04421.x
Veith, T. L., Wolfe, M. L., Heatwole, C. D., & Bosch, D. J. (2001). Watershed level optimization of BMP placement for cost-effective NPS pollution reduction. Proc. 2001 ASAE Annual Meeting. ASAE. https://doi.org/10.13031/2013.5528
Yuan, Y., Dabney, S. M., & Bingner, R. L. (2002). Cost effectiveness of agricultural BMPs for sediment reduction in the Mississippi Delta. J. Soil Water Conserv., 57(5), 259-267.