RTI International

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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

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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

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Costs, Co-Benefits and Net Costs

Costs of Control Projects

Ecosystem Service Co-Benefits

Net Costs

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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

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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

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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

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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

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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

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Model Scenarios

Restrictions on agricultural land conversion and increased agricultural land rental rates

Required reductions from urban sources

Higher credit ratio for NPS reductions

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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

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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

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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

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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

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Questions?

EPA Report http://www.epa.gov/research/docs/chesapeake-bay-pilot-report.pdf

Contact:

Ross Loomis

Economist

rloomis@rti.org

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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