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RTI International
RTI International is a trade name of Research Triangle Institute. www.rti.org
Tradeoffs in Achieving TMDLs – Ecosystem Services and Cultural Values in the
Chesapeake BayLisa A. Wainger1, George Van Houtven2, Ross
Loomis2, Jay Messer3, Marion Deerhake2
1 University of Maryland Center for Environmental Science, Solomons, MD
2 RTI International, RTP, NC3 Retired; formerly of US EPA Office of Research
and Development
Collaborators
EPA ORD – Lisa Wainger, Jay Messer, Rob Wolcott, Andy Almeter
RTI – George Van Houtven, Marion Deerhake, Robert Beach, Dallas Wood, Mary Barber, Mike Gallaher, Jamie Cajka, David Chrest, Maggie O’Neill, Michele Cutrofello, Tony Lentz
Abt Associates – Isabelle Morin, Viktoria Zoltay
2
The Potomac River watershed:
– 14,700 sq mile area– 23% of CB watershed– 97 significant
municipal and industrial wastewater facilities
– 13% (1.2M acres) urban
– 26% (2.5M acres) agricultural land (crop and pasture)
3
Case Study Area
Chesapeake Bay TMDL TMDL jurisdiction and sector
allocations were developed based on equity:
– More reductions from watersheds with a greater impact on Bay water quality
– More effort required from wastewater treatment facilities, equal effort required from all other sources “Everyone doing everything everywhere”
scenario defines maximum effort
– Cost effectiveness and environmental co-benefits not considered
Agricu
lture
Urban
Run
off
Was
tewat
er0
20
40
60
80
100
120
Average Annual Ni-trogen Delivered to
the Chesapeake Bay
2010TMDL
mil
lio
n l
bs
Questions to address
How do alternative policies affect:
– Costs of achieving the TMDLs?
– Generation of other ecosystem services?
5
Optimization Framework
Mixed integer linear programming (MILP) problem in the General Algebraic Modeling System (GAMS)
Relies on some data developed for and model output from the Chesapeake Bay Program’s Phase 5.3 Community Watershed Model (CBWM) (USEPA, 2010)
Includes new and newly synthesized data Adapts existing models to quantify ecosystem service
outputs Uses benefit transfer to value services
6
Optimization Objectives - Least-Cost Solution
𝑀𝑖𝑛 𝑇𝐶= 𝑀𝑖𝑛 ቌ 𝐶𝑖𝑗𝐴𝑖𝑗 + 𝑉𝑘𝑙𝑈𝑘𝑙𝑘𝑙𝑖𝑗 ቍ
Cij = Cost per acre of NPS practice i in location j, Aij = Acres of implementation of BMP i within land-river segment j; Vkl = Cost of PS project k at plant l; Ukl = 1 if project k at plant l is adopted, 0 otherwise
Subject to: 1. Reductions for all pollutants (TN, TP, sediment) ≥
Targets2. Aij ≤ available acres for NPS practice i3. No more than 1 option k is used, per plant l
7
Costs, Co-Benefits and Net Costs
Costs of Control Projects
Ecosystem Service Co-Benefits
Net Costs
8
Optimization Objectives - Least-NET-Cost Solution
𝑀𝑖𝑛 𝑇𝐶= 𝑀𝑖𝑛 ቌ 𝐶𝑖𝑗𝐴𝑖𝑗 + 𝑉𝑘𝑙𝑈𝑘𝑙𝑘𝑙𝑖𝑗 − 𝑆𝑛𝑄𝑛(𝑖,𝑗)𝑛 ቍ
Sn = ecosystem service unit value Qn = units of ecosystem service provided n = ecosystem service type
9
Management / Restoration Practices Included
Point Source Projects POTW Advanced Nutrient
Removal Industrial Advanced Nutrient
Removal
Nonpoint Source Urban Stormwater BMPs
Extended Detention Ponds Bio-retention Planters Urban Forest Buffers Urban Grass Buffers Urban Wetlands
Nonpoint Source Agricultural BMPs
Forest Riparian Buffers Grass Riparian Buffers Conversion to Forest Natural Revegetation Wetland Restoration Livestock Exclusion Winter Cover Crops No-Till Agriculture Reduced Fertilizer Application
10
No CAFO BMPs or Septic upgrades & hookups
Annual Costs and Load Reductions for Urban Control Projects
Point Sources– 3 “tiers” of wastewater treatment at significant municipal and
industrial facilities– Costs and removals based on EPA analysis of point source
controls in the Chesapeake Bay watershed Urban Stormwater BMPs
11
BMP Total Annual Cost per BMP Acre ($/acre/yr)
Removal Efficiencies (%)
Total Nitrogen Total
Phosphorous Total Suspended
Solids
Extended Detention $4,460 20% 20% 60%
Bioretention $66,647 48% 60% 68%
Grass Buffer $6,676 32% 40% 53%
Forest Buffer $364 50% 60% 60%
Wetlands $601 20% 45% 60%
Based on Abt Associates (2010)
Annual Costs and Load Reductions for Agricultural BMPs
Costs include
– Installation and operation & maintenance (O&M) based on literature review and summary
– Land costs (county-level avg. rental rates for crop or pasture land)
Nutrient/sediment removals based on CBWM and other sources
12
BMP Total Annual Cost per BMP Acre ($/acre/yr)
Removal Efficiencies (%)
Total Nitrogen Total
Phosphorous Total Suspended
Solids
Forest Buffers $163–291 19–65% 30–45% 40–60%
Grass Buffers $99–226 13–46% 30–45% 40–60%
Wetland Restoration $236–364 7–25% 12–50% 4–15%
Livestock Exclusion $81–117 9–11% 24% 30%
Cover Crops $31 34–45% 15% 20%
No-till $14 10–15% 20–40% 70%
Reduced Fertilizer Application $37
15% 0% 0%
Ecosystem Service Co-Benefits by BMP
13
Model Scenarios
Restrictions on agricultural land conversion and increased agricultural land rental rates
Required reductions from urban sources
Higher credit ratio for NPS reductions
14
15
Effects of Restricting Agricultural Land Conversion on Cumulative TMDL Costs
Unrestricted Base Case10% transaction costs; 1:1 NPS:PS
No ag conversion beyond 100’ buffers
$12M ES co-benefits $4M ES co-benefits
Effects of Alternative Agricultural Policy on Least-Cost Mix of NPS Practices
16
Scenario 1 Base Case
Scenario 2a No Land Conversion
Beyond 100 ft
Scenario 2b2.2x Ag Land Rental
Costs
0
100
200
300
400
500
600
700
Urban Stormwater BMPs Ag Working Land BMPs Ag Land Conversion BMPs
Thou
sand
Acr
es
Effect of Urban Allocation on TMDL Costs
17
0% 5% 10% 15% 20% 25%$0
$200
$400
$600
$800
$1,000
$1,200
Total Annual Cost
$ M
illi
on
s
Percentage of Pollutant Reduction Required from Urban Sources
$12M ES co-benefits
$10M ES co-benefits
Sce-nario
1Base Case
Sce-nario
4a2:1
Credit Ratio
Sce-nario
1Base Case
Sce-nario
4a2:1
Credit Ratio
-20
0
20
40
60
80
100
NET COSTS
COSTS - Urban
COSTS - Ag
COSTS - Point Sources
$ M
illio
ns
Least-NET-Cost Solu-tion
Least-Cost Solution
Effect of Credit Ratios (NPS:PS) on TMDL Costs and Net Costs
18
Results Summary
A least-cost TMDL allocates the vast majority of effort in the Potomac Basin to agricultural BMPs
– Roughly 50:50 mix of working lands and land conversions from base scenario with 1:1 credit ratios, 10% transaction costs, and 1X rental rates
Restrictions on ag land conversion or higher rental rates result in the substitution of working land BMPs
– Highest ecosystem services from BMPs that convert agricultural land
– Working land options highly cost-effective compared to gray infrastructure & produce co-benefits
Low NPS:PS credit ratios produce the most cost savings but high credit ratios result in more ES co-benefits
19
Questions?
EPA Report http://www.epa.gov/research/docs/chesapeake-bay-pilot-report.pdf
Contact:
Ross Loomis
Economist
rloomis@rti.org
21
Load Reduction Targets by Basin (millions of lbs)
Basin Nitrogena Phosphorus Sediment
Eastern Shore of Chesapeake Bay 4.74 0.27 38.88 James River Basin 8.18 0.89 326.23 Patuxent River Basin 0.20 0.05 7.67 Potomac River Basin 6.77 1.03 509.72 Rappahannock River Basin 1.01 0.18 51.90 Susquehanna River Basin 33.14 1.16 529.02 Western Shore of Chesapeake Bay 4.91 0.26 38.24 York River Basin 0.95 0.08 23.80
Total 59.91 3.92 1525.47 a Excludes expected reductions in delivered loads attributable to non-tidal atmospheric deposition in the watershed
Million lbs
TMDL Allocations as Load Reductions Targets by Basin
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