MEMORANDUM 

TO: Steam Electric ELG Rulemaking Record 

FROM: Lydia Lambert, ERG 

DATE: April 19, 2013 

 

SUBJECT: Downstream Model Supporting Documentation (DCN SE03891) 

ERG is providing technical support to the U.S. Environmental Protection Agency (EPA) 

for development of revised effluent limitations guidelines and standards (ELGs) for the Steam 

Electric Power Generating Point Source Category. In support of the development of revised 

ELGs, ERG developed the following resources to evaluate pollutant concentrations in the 

downstream receiving water reaches and to calculate the resulting pollutant concentrations in fish 

tissue. ERG then developed resources to compare the pollutant concentrations to water quality, 

wildlife, and non-cancer and cancer human health benchmarks to assess the number of improved 

river miles associated with the regulatory options (Options 1, 2, 3, 4, and 5) under the current 

profile1

: 

 Downstream Data Preparation Database; 

 Downstream Wildlife and Human Health Models; 

 Downstream Water Quality General Matrix Database; 

 Downstream Wildlife General Matrix Database; and 

 Downstream Human Health General Matrix Database. 

 EPA’s economic contractor, Abt Associates, calculated downstream receiving water 

concentrations using EPA’s Risk-Screening Environmental Indicators (RSEI) model. ERG then 

used the downstream receiving water concentrations as inputs for the wildlife and human health 

models described in Section 4.1.2 (Assessment of the Surface Water Exposure Pathway), 

Appendix D (Wildlife Model Methodology), and Appendix E (Human Health Model 

Methodology) of the Final Environmental Assessment for the Proposed Effluent Limitations 

Guidelines and Standards for the Steam Electric Power Generating Point Source Category (EA 

Report) (DCN SE01995). For further details on the RSEI model methodology and assumptions, 

see the Benefit and Cost Analysis for the Proposed Effluent Limitations Guidelines and 

Standards for the Steam Electric Power Generating Point Source Category (Benefits and Cost 

Analysis) (DCN SE03172). 

 Abt Associates did not calculate downstream receiving water concentrations for Options 

3a, 3b, or 4a, and ERG did not run the wildlife and human health models for these three options. 

 

1

Current profile includes waste streams generated by air pollution controls that will likely be in operation at steam 

electric plants at the time EPA takes final action on this rulemaking. 
Memorandum 

April 19, 2013 

Page 2 

The methodology used by ERG to estimate downstream impacts for these three regulatory 

options is presented in Appendix G (Methodology for Non-Modeled Options) of the EA Report.

The results of the downstream modeling under the current profile are presented in Section 

6.5 (Environmental and Human Health Improvements in Downstream Surface Water) of the EA 

Report. 

 A comprehensive listing of the downstream model supporting documentation for the 

current profile is presented in Table 1-1 below. This table provides the document control number 

(DCN), title, and abstract of each record item, and identifies whether the record item contains 

Confidential Business Information (CBI). ERG did not conduct downstream modeling for the 

future profile2. 

Table 1-1. Current Profile Downstream Record Items 

DCN Title (Date) Abstract CBIa

SE03537 Downstream Data 

Preparation for Wildlife and 

Human Health Model - 

Current Profile (101212) 

Database used to prepare the raw data tables of downstream 

receiving water concentrations using EPA’s RSEI model for 

the Wildlife and Human Health Model. These results are 

used to populate the Downstream Wildlife and Human 

Health Models. 

Yes 

SE03538 Downstream Wildlife and 

Human Health Model - 

Current Profile - Baseline 

(101212) 

Database used to quantify potential impacts to aquatic life, 

wildlife, and human health downstream of the immediate 

discharge zone for baseline under the current profile. These 

results are used to populate the Downstream Wildlife 

Improvements Database and the Downstream Human Health 

Improvements Database. 

Yes 

SE03539 Downstream Wildlife and 

Human Health Model - 

Current Profile - Option 1 

(101212) 

Database used to quantify potential impacts to aquatic life, 

wildlife, and human health downstream of the immediate 

discharge zone for Option 1 under the current profile. These 

results are used to populate the Downstream Wildlife 

Improvements Database and the Downstream Human Health 

Improvements Database. 

Yes 

SE03540 Downstream Wildlife and 

Human Health Model - 

Current Profile - Option 2 

(101212) 

Database used to quantify potential impacts to aquatic life, 

wildlife, and human health downstream of the immediate 

discharge zone for Option 2 under the current profile. These 

results are used to populate the Downstream Wildlife 

Improvements Database and the Downstream Human Health 

Improvements Database. 

Yes 

SE03541 Downstream Wildlife and 

Human Health Model - 

Current Profile - Option 3 

(101212) 

Database used to quantify potential impacts to aquatic life, 

wildlife, and human health downstream of the immediate 

discharge zone for Option 3 under the current profile. These 

results are used to populate the Downstream Wildlife 

Improvements Database and the Downstream Human Health 

Improvements Database. 

Yes 

 

2

Future profile includes waste streams generated by future installations of air pollution controls at steam electric 

power plants that may result from some recently promulgated Clean Air Act requirements.
Memorandum 

April 19, 2013 

Page 3 

Table 1-1. Current Profile Downstream Record Items 

DCN Title (Date) Abstract CBIa

SE03542 Downstream Wildlife and 

Human Health Model - 

Current Profile - Option 4 

(101212) 

Database used to quantify potential impacts to aquatic life, 

wildlife, and human health downstream of the immediate 

discharge zone for Option 4 under the current profile. These 

results are used to populate the Downstream Wildlife 

Improvements Database and the Downstream Human Health 

Improvements Database. 

Yes 

SE03543 Downstream Wildlife and 

Human Health Model - 

Current Profile - Option 5 

(101212) 

Database used to quantify potential impacts to aquatic life, 

wildlife, and human health downstream of the immediate 

discharge zone for Option 5 under the current profile. These 

results are used to populate the Downstream Wildlife 

Improvements Database and the Downstream Human Health 

Improvements Database. 

Yes 

SE03536 Downstream Water Quality 

Improvements Database - 

Current Profile - Baseline 

and Options (100912) 

Database used to compare downstream pollutant 

concentrations in the receiving water, calculated using EPA’s 

RSEI model, to benchmarks. These results are used to 

identify the water quality improvements for downstream 

waters under the evaluated regulatory options. 

Yes 

SE03547 Downstream Wildlife 

Improvements Database - 

Current Profile - Baseline 

and Options (101512) 

Database used to calculate the downstream wildlife results 

(i.e., comparison of fish tissue concentrations to benchmarks 

where wildlife may be impacted) from the downstream 

Human Health and Wildlife Model for baseline and the 

options under the current profile. These results are used to 

identify the wildlife improvements for downstream waters 

under the evaluated regulatory options. 

Yes 

SE03544 Downstream Human Health 

Improvements Database - 

Current Profile - Baseline 

and Option 1 (101212) 

Database used to calculate the downstream human health 

results from the downstream Human Health and Wildlife 

Model for baseline and Option 1 under the current profile. 

The results include potential non-cancer and cancer impacts 

to human health in the downstream reaches. These results are 

used to identify the human health improvements for 

downstream waters under the evaluated regulatory Option 1. 

Yes 

SE03545 Downstream Human Health 

Improvements Database - 

Current Profile - Option 2 

and Option 3 (101212) 

Database used to calculate the downstream human health 

results from the downstream Human Health and Wildlife 

Model for Option 2 and Option 3 under the current profile. 

The results include potential non-cancer and cancer impacts 

to human health in the downstream reaches. These results 

are used to identify the human health improvements for 

downstream waters under the evaluated regulatory Options 2 

and Option 3. 

Yes 

SE03546 Downstream Human Health 

Improvements Database - 

Current Profile - Option 4 

and Option 5 (101212) 

Database used to calculate the downstream human health 

results from the downstream Human Health and Wildlife 

Model for Option 4 and Option 5 under the current profile. 

The results include potential non-cancer and cancer impacts 

to human health in the downstream reaches. These results are 

used to identify the water quality improvements for 

downstream waters under the evaluated regulatory Option 4 

and Option 5. 

Yes 

a – Record items containing CBI have been removed from the public record.