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Integrated monitoring, modeling, and economic analysis to inform a watershed implementation plan for nutrient management

Christopher Nietch and Matthew Heberling. USEPA/Office of Research and Development, Cincinnati OH. And two dedicated field and lab technicians and a full-time modeler

Disclaimer: The views expressed in this presentation are those of the authors and do not necessarily represent the views or policies of the U.S. EPA.

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• Gaining a better understanding of the potential for Water Quality Trading (WQT) was the impetus for this research.

• WQT, here nutrient trading, is a market-based policy and non-regulatory approach. It is attractive as a cost-effective and flexible approach, but has had limited success managing the nutrient pollution problem

• Trading is a compliance option for point sources like waste water treatment plants (WWTPs) under the Clean Water Act (CWA). Recently EPA announced it was updating its WQT policy (Ross Memorandum, Feb 2019)

• Policy updates include providing guidance to stakeholders and promoting increased investment in conservation actions (aka Agricultural Best Management Practices (agBMPs)

• We developed a workflow to arrive at a “low-cost” implementation plan for nutrient management and to consider WQT feasibility

• We now are studying the realities of implementation in an experimental watershed

Workflow for watershed nutrient management

• We identified a 12-step workflow for deriving nutrient reduction costs and considering the supply and demand sides of a potential WQT market

• Monitoring > modeling > cost analysis > more monitoring/modeling

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Experimental Watershed

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Upper East Fork Watershed (UEFW)

• Harsha Lake: Flood Control and Drinking Water Reservoir experiencing severe Harmful Algal Bloom (HAB) problems• 1.5 million visitors annually

• UEFW- 64% agriculture• 104,000 acres of row crops, 2/3rd soybeans• 9 WWTPs • Septic Systems – 11,000 with 27% failure rate

Set Strategic Monitoring Sites

Critical Components1. At least one large scale WQ2 ‘super’

gauge.2. Multiple small-scale sites strategically

located to characterize unique land use/soil type combinations

3. Point Sources and proximal downstream conditions

4. HUC12-scale sites used to determine nutrient reduction requirements and track progress at intermediate spatial scales.

Secondary Considerations1. In-stream attenuation sites2. Edge-of-field evaluation site3. BMP performance measurement sites4. Critical Areas (e.g. beaches and DWTP

intakes)

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Upper East Fork WatershedMonitoring Sites

Equals a 12 site minimum for 800 km2 system with 12 HUC12s; or ~ 1 per HUC 12 in the UEFW

Establish Stakeholder Workgroup

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The East Fork Watershed (EFW) Cooperative

• Federal Partners

• State Partners

• Local PartnersLocal Farmers

• Leverages monitoring and management effort to:• Maintain a network of sample sites and

analytical tools for researching watershed-scale restoration, especially for HABS

• Since 2009 the EFWCoop has used its resources to:• Document historical changes in river water

quality and coincident shifts in algal communities in Harsha Lake

• Facilitate focused research studies• Support the testing of watershed

modeling tools • Engage a broader stakeholder community

to promote watershed protection with agBMPs

Watershed Modeling

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Goal = Develop transparent modeling practices using existing tools

• Soil and Water Assessment Tool (SWAT) –Semi-distributed, physically based, capable of simulating a diversity of crop types and management options and operations

• SWAT- Calibration and Uncertainty Program (CUP) for uncertainty analysis

• Hydrologic and Water Quality System (HAWQS)- Web-based user friendly DSS supported by EPA-OW

• Use model parametric uncertainty to obtain distributions for agBMP reduction efficiencies

Baseline

w/agBMP

SWAT-Based Watershed Modeling Approach

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• Used to set nutrient reduction requirements among sources

• Must have high spatial resolution for agBMP placement and to study trading scenarios

• Simulates watershed-scale BMP effectiveness scenarios for cost comparisons and progress tracking

P Runoff Map for Priority HUC12

Set Defensible Targets

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Nutrient Targets set for the Water Quality Trading Research – obtained from weekly monitoring

TP ppb(Ref = 55) (Target=60)

TN ppb(Ref= 433)(Target=700)

Nutrient Source Distribution and Reduction Requirements

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TP % contribution of ~100,000 kg.yr-1

TN% contribution of ~1,000,000 kg.yr-1

Point Source/ Location

Existing Mean Effluent TP

(mg/l)

Compliance Mean

Effluent TP (mg/l)

Annual TP Reduction Required

(kg/yr)

Annual TP Load (kg/yr)

Existing Mean Effluent TN

(mg/l)

Compliance Mean Effluent

TN (mg/l)

Annual TN Reduction Required

(kg/yr)

Annual TN Load (kg/yr)

SnowHill 2.315 0.162 9.6 10.30 12.37 7.42 20.25 51NewVienna 4.719 0.057 706 715 14.31 0.86 1946 2070Lynchburg 2.503 0.080 577 596 12.59 2.27 2674 3261

RollingAcres 2.311 0.092 25 26 12.01 2.88 104 137Fayetteville 1.934 0.464 167 220 10.81 10.81 0 1218

Williamsburg 1.130 0.904 92 460 11.01 11.01 0 4910HollyTowne 2.303 0.334 120 140 22.63 4.87 1069 1362ForestCreek 2.305 0.092 60 62 24.80 2.67 595 666LocustRidge 2.329 0.140 12 13 11.21 6.50 25 60WWTP Total 1768 2242 6433 13735Watershed 0.234 0.039 93645 112150 3.379 0.405 983128 1117191% of Total 1.9% 0.7%

Point Sources & Watershed Load Reduction Required

Summary of Effectiveness of Alternatives

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• agBMPs scenarios: • Residue Management, Cover

Crops, Filter Strips, Wetlands, Grassed Waterways, Septic Repair, and Reducing Fertilizer

• In terms of $/lb nutrient removal: • Septic Repair >> WWTP

upgrade >> agBMPs• Including uncertainty in treatment

efficiencies doubles or triples the base cost estimates

Efficiency uncertainty

Cost of Nutrient Removal

Location uncertainty

Cost incentives are high for WWTPs, but compared to the potential supply of credits the demand is very low = a very thin market. Need more buyers for WQT to be viable

Establish “low-cost” Management Plan

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For 104,000 acres of row-crops

• The Upper East Fork Watershed minimally needs:• 1040 acres of wetlands• 2600 acres of filter strips• 43,000 acres of cover crops

to reduce Phosphorus loads to meet target in watershed streams

• Annual Cost = $3.6 to $8.0 Mil• Think of this as necessary

demand-side of WQT market if there was buyers

Context for ‘fix-it’ costs• $3.6 to 8 million annually to manage the UEFW for

phosphorus pollution, or $250 – 600K per HUC12.• $30 million net income from farming annually: Like a

20% tax!• Recreation in Lake Harsha adds $2 million to economy• DWTP spends ~ $650K to ensure safety from algal toxins

• Soil and Water Conservation Districts (SWCDs) have obligated $2.75 million in EQIP funds for nutrient reduction projects• Including 17,000 acres in cover crops – growing from ~

100 acres over the last 10 yrs• 319 Program funded one $100K project in the last four yrs.• H2Ohio Bill plans to spend $85 million over next 10 yrs for

nutrient reduction with specific attention on the Maumee River Watershed driving Western Basin Lake Erie HAB Problem, or ~ $250K per HUC12

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Prioritizing EQIP Projeusing the UEFW SWATModel

cts

So, costs to fix the UEFW appear tractable relative to what the State will spend to fix Lake Erie

Implementation Plan Reality Check – Wetlands

• Subbasin 72 is 1172 acreswith 366 acres of row crop

• 31% of flow passes through3.66 acres of wetland

• 0.54 MGD!

Wetland Modeling in SWAT, contextual example

For context, the WWTP in Williamsburg, OH treats 0.1 MGD.

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How much water has to move through the 1040 acres of wetlands at watershed scale? = 150 MGD!

Wetland (3.7 acres)

• So, even if we can get 1000 acres of wetlands on the ground, moving therequired amount of water through them is going to be very tricky

Conclusions• Effective nutrient management relies on coupled and

long-term monitoring and modeling at multiple spatial scales and relies on an active stakeholder group

• Management cost estimation should be standardized (e.guse a one model approach) across the system and made transparent; allows for the feasibility of a market-base approach to be considered

• Implementation at the magnitudes required will be costly and tricky, benefits should balance, watch for modeling disconnects with reality

• Continuous monitoring AND modeling will be needed to track progress and refine model estimates

• This is different from current approach that focuses on survey type assessment monitoring and one-time modeling for TMDL development

• At 1 monitoring site per HUC 12 and 1500 HUC12s in Ohio with 88 SWCDs, that would be 17 per district and it could be coupled to NPDES reporting cyberinfrastructure, it is not intractable

0.1 mgd WWTP, Williamsburg, OH

Corn growing through cover crop

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