Social Cost of Nutrient Pollution in Streams and Rivers

6th Annual Social Cost of Water Pollution Workshop

David Smith, Charles Griffiths and Bryan Parthum

National Center For Environmental Economics, U.S. Environmental Protection Agency: *The views expressed in this presentation are those of the authors and do not necessarily reflect the views or policies of the US Environmental Protection Agency.

What is the Social Cost of Nutrient Pollutants?

  • The monetary value of the net social damages from applying or emitting an additional kilogram of the nutrient.
  • This study is focused on damages from loadings to stream reaches.

Keiser, Kling, Phaneuf. 2019. Adapted from Freeman, Herriges, and Kling.

Why Social Cost of Nutrient Pollution?

  • Convenient and Timely
  • Application to policy analysis does not require water quality or economic modeling
  • Useful for Federal, State and Local agencies
  • Consensus building around methods and models
  • Controlled nutrient pulses allow for useful insight into water quality and economic modeling.
  • Helpful to identify gaps in knowledge

Comparing Social Costs of different pollutants

Greenhouse Gases (GHGs)

  • Global
  • Well mixed
  • Stock pollutant
  • Spatially invariant
  • Long-lived
  • Long-term damages

Nutrient pollution (NP)

  • Local/regional
  • Routed
  • Flow pollutant
  • Spatially variant
  • Short-lived
  • Near-term damages

Literature

  • Hansen and Ribaudo. 2008.
  • Griffiths et al. 2012
  • Keeler et al. 2016
    • $0.001 to $50 per kg N (Minnesota)
    • Varies by nutrient form (ammonia, nitrite, nitrate)
  • Keiser, Kling, Phaneuf. 2019 (RFF)
  • Andarge, Dolph, Finlay, Hoque, Ji, Keiser, Kling, Phaneuf, Shr, Vossler. 2022

Preview of Results

A National Integrated Assessment Model

Socioeconomics

  • Population and income (US Census)
  • Point Source (NPDES)
  • Land Use (NLCD, CDL, ICLUS)
  • Reservoirs (NID)
  • Water Use (USGS)

Water Quality

  • Baseline Data and SWAT Setup (HAWQS v2.0 beta API)
  • Baseline Subbasin Loads (SWAT 2012 rev. 688)
  • Nutrient Pulse (Modified SWAT 2012 rev. 688, SWAT-Channel)

Damages (Discounting)

  • BenSPLASH (Alpha version, batch mode)
  • Water Quality Index (6 parameter)
  • Benefits Transfer based on Meta-analysis (EPA 2015)
  • 100 km buffer

Water Quality Model Schematic

Water Quality Model Schematic

Mid Atlantic Region

  • 1 of 18 HUC02 regions
  • Calibrated for Flow in HAWQS
  • 1,975 HUC12 subbasins/reaches
  • 70,861 Hydrologic Response Units (0.50 km2)

Mid Atlantic Region

Baseline

Baseline: Flow

Flow

Baseline: Nutrient Delivery

Delivery Ratio

Baseline: Nutrient Concentrations

Nutrient Concentrations

Baseline: Other Concentrations

Nutrient Concentrations

Nutrient Pulses and Social Cost of Nutrient Pollutants

  • Pulse size: 365,000 kg (1,000 kg per day)
  • Pulse year plus 3 years
  • 1,975 subbasins
  • 6 nutrient forms
  • 30 years (5-year increments)
  • 70k+ SC-NPs

Modified Soil and Water Assessment Tool (SWAT)

flowchart LR
subgraph Channel ["Channel (Runtime 2%) "]
RCH1["Reach 1"]:::someclass
RCH2["Reach 2"]:::someclass
PS1(("Point \n Source 1")):::someclass
PS2(("Point \n Source 2")):::someclass
end
subgraph Nonpoint ["Nonpoint (Runtime 98%) "]
subgraph SUB1 ["Subbasin 1"]
HRU1["HRU 1"]:::someclass
HRU2["HRU 2"]:::someclass
end
subgraph SUB2 ["Subbasin 2"]
HRU3["HRU 3"]:::someclass
HRU4["HRU 4"]:::someclass
end
end

RCH1 --> RCH2
SUB1 ---> RCH1
SUB2 ----> RCH2
PS1 --> RCH1
PS2 --> RCH2

classDef someclass fill:#FFFFFF, stroke:#000000
  style Nonpoint fill:#FFFFFF, stroke:#000000
  style Channel fill:#FFFFFF, stroke:#000000
  style SUB1 fill:#FFFFFF, stroke:#000000
  style SUB2 fill:#FFFFFF, stroke:#000000

SWAT-Channel

Example Subbasin

Example Subbasin: Nutrient Concentration Response to Pulse

Changes in Nutrient Concentration

Example Subbasin: Dissolved Oxygen Response to Pulse

Example Subbasin: Water Quality Index

Water Quality Index

Example Subbasin: Willingness to Accept

Household WTA

Total WTA

Results

Social Cost of Nutrient Pollution

Social Cost of Nutrient Pollution

Conclusion

  • Social cost of nutrients has large spatial variation
  • Complex biochemical system
  • Nutrient form matters
  • What increases social cost?
    • Lower water flow (concentrations = load / flow)
    • Higher delivery ratios (lower residence time, higher concentrations downstream)
    • Larger population and incomes downstream
    • Form

Next Steps

  • Calibration (water quality)
  • Other Pollutants (CBOD, sediment)
  • HUC02s (17 others)
  • Compare benefit estimates for EPA rules using SC-NP
  • Environmental Justice
  • Uncertainty
  • Social cost of nutrient application
  • Social benefits of land retirement