MEMORANDUM 

TO: Steam Electric ELG Rulemaking Record 

FROM: Lydia Lambert, ERG 

DATE: April 19, 2013 

 

SUBJECT: Water Quality Model Supporting Documentation (DCN SE03888) 

1.0 SUMMARY OF SUPPORTING DOCUMENTATION

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 calculate pollutant concentrations in the water 

column and sediment of the immediate receiving water and evaluate the impacts that receiving 

water concentrations pose to aquatic life and human health under the current profile and future 

profile1

 for the baseline and five regulatory options (Options 1, 2, 3, 4, and 5): 

 Water Quality Model; 

 Water Quality Model Comparisons Database; 

 Water Quality Model Summary Tables Database; and 

 Water Quality Model Summary Tables Spreadsheet. 

 The methodology of the water quality model under the current profile and future profile 

is presented in the following documentation: 

 Water Quality Model: Plant and Receiving Water Characteristics Memorandum 

(DCN SE01955) – This memorandum specifies the methodology used to identify the 

characteristics of the immediate receiving waters evaluated in the water quality 

model. 

 Pollutant Loadings Supporting Documentation Memorandum (DCN SE03887) – This 

memorandum identifies the supporting documentation used to calculate the pollutant 

loadings evaluated in the water quality model. 

 

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. 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 2 

 

 Final Environmental Assessment for the Proposed Effluent Limitations Guidelines 

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

Report) (DCN SE01995) – Section 4.1.2 (Assessment of the Surface Water Exposure 

Pathway) of this report provides an overview of the water quality model. Appendix C 

(Water Quality Model Methodology) of this report presents the model equations, 

input values, pollutant benchmarks, and methodology limitations/assumptions. 

 ERG did not calculate pollutant concentrations in the water column and sediment of the 

immediate receiving water for Options 3a, 3b, and 4a using the water quality supporting 

documentation listed above. The methodology used for these three regulatory options is 

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

1.1 Current Profile Analyses

The results of the water quality model under the current profile are presented in the 

following sections of the EA Report: 

 Section 5.3.1 (Water Quality Impacts); 

 Section 6.2 (Key Environmental Improvements); 

 Section 6.3 (Pollutant-Specific Improvements); and 

 Section 7 (Conclusions). 

 A comprehensive listing of the water quality 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). 

Table 1-1. Current Profile Water Quality Record Items 

DCN Title (Date) Abstract CBIa

SE02993 Water Quality Model - 

Current Profile - Baseline 

(082212) 

Database used to calculate the total and dissolved receiving 

water concentrations and total sediment concentrations and 

to identify pollutant concentrations that exceed benchmarks 

for aquatic life and human health in the immediate discharge 

zone for baseline under the current profile. Generates inputs 

for Wildlife and Human Health Models. 

Yes 

SE02994 Water Quality Model - 

Current Profile - Option 1 

(082212) 

Database used to calculate the total and dissolved receiving 

water concentrations and total sediment concentrations and 

to identify pollutant concentrations that exceed benchmarks 

for aquatic life and human health in the immediate discharge 

zone for Option 1 under the current profile. Generates inputs 

for Wildlife and Human Health Models. 

Yes 
Memorandum 

April 19, 2013 

Page 3 

 

Table 1-1. Current Profile Water Quality Record Items 

DCN Title (Date) Abstract CBIa

SE02995 Water Quality Model - 

Current Profile - Option 2 

(082212) 

Database used to calculate the total and dissolved receiving 

water concentrations and total sediment concentrations and 

to identify pollutant concentrations that exceed benchmarks 

for aquatic life and human health in the immediate discharge 

zone for Option 2 under the current profile. Generates inputs 

for Wildlife and Human Health Models. 

Yes 

SE02996 Water Quality Model - 

Current Profile - Option 3 

(082212) 

Database used to calculate the total and dissolved receiving 

water concentrations and total sediment concentrations and 

to identify pollutant concentrations that exceed benchmarks 

for aquatic life and human health in the immediate discharge 

zone for Option 3 under the current profile. Generates inputs 

for Wildlife and Human Health Models. 

Yes 

SE02997 Water Quality Model - 

Current Profile - Option 4 

(082212) 

Database used to calculate the total and dissolved receiving 

water concentrations and total sediment concentrations and 

to identify pollutant concentrations that exceed benchmarks 

for aquatic life and human health in the immediate discharge 

zone for Option 4 under the current profile. Generates inputs 

for Wildlife and Human Health Models. 

Yes 

SE02998 Water Quality Model - 

Current Profile - Option 5 

(082212) 

Database used to calculate the total and dissolved receiving 

water concentrations and total sediment concentrations and 

to identify pollutant concentrations that exceed benchmarks 

for aquatic life and human health in the immediate discharge 

zone for Option 5 under the current profile. Generates inputs 

for Wildlife and Human Health Models. 

Yes 

SE02999 Water Quality Model 

Comparisons Database - 

Current Profile - Option 1 

(082212) 

Database used to compare the Water Quality Model results 

between baseline and Option 1 under the current profile. 

Generates inputs for Water Quality Model Summary Tables 

Database. 

Yes 

SE03501 Water Quality Model 

Comparisons Database - 

Current Profile - Option 2 

(082212) 

Database used to compare the Water Quality Model results 

between baseline and Option 2 under the current profile. 

Generates inputs for Water Quality Model Summary Tables 

Database. 

Yes 

SE03502 Water Quality Model 

Comparisons Database - 

Current Profile - Option 3 

(082212) 

Database used to compare the Water Quality Model results 

between baseline and Option 3 under the current profile. 

Generates inputs for Water Quality Model Summary Tables 

Database. 

Yes 

SE03503 Water Quality Model 

Comparisons Database - 

Current Profile - Option 4 

(082212) 

Database used to compare the Water Quality Model results 

between baseline and Option 4 under the current profile. 

Generates inputs for Water Quality Model Summary Tables 

Database. 

Yes 

SE03504 Water Quality Model 

Comparisons Database - 

Current Profile - Option 5 

(082212) 

Database used to compare the Water Quality Model results 

between baseline and Option 5 under the current profile. 

Generates inputs for Water Quality Model Summary Tables 

Database. 

Yes 
Memorandum 

April 19, 2013 

Page 4 

 

Table 1-1. Current Profile Water Quality Record Items 

DCN Title (Date) Abstract CBIa

SE03505 Water Quality Model 

Summary Tables Database - 

Current Profile (082212) 

Database used to summarize the Water Quality Model results 

for baseline and regulatory options under the current profile. 

Generates the Water Quality Model Summary Tables 

Spreadsheet. 

No 

SE03506 Water Quality Model 

Summary Tables 

Spreadsheet - Current 

Profile (082812) 

Spreadsheet that summarizes the Water Quality Model 

results for baseline and regulatory options under the current 

profile. 

No 

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

1.2 Future Profile Analyses

The results of the water quality model under the future profile are presented in the Flue 

Gas Desulfurization Future Profile Sensitivity Analysis Memorandum (DCN SE01989). A 

comprehensive listing of the water quality model supporting documentation for the future profile 

is presented in Table 1-2 below. 

Table 1-2. Future Profile Water Quality Record Items 

DCN Title (Date) Abstract CBIa

SE03509 Water Quality Model - 

Future Profile – 

Questionnaire and IPM 

(091112) 

Database used to calculate the total and dissolved receiving 

water concentrations and total sediment concentrations and 

to identify pollutant concentrations that exceed benchmarks 

for aquatic life and human health in the immediate discharge 

zone under baseline future profile. This scope includes plants 

with predicted future air pollution control installations 

identified in the Integrated Planning (IPM) projections for 

the final Mercury and Air Toxics Standards (MATS) rule 

and EPA’s Questionnaire for the Steam Electric Power 

Generating Effluent Guidelines. Generates inputs for 

Wildlife and Human Health Models. 

Yes 

SE03510 Water Quality Model - 

Future Profile - IPM Only 

(091112) 

Database used to calculate the total and dissolved receiving 

water concentrations and total sediment concentrations and 

to identify pollutant concentrations that exceed benchmarks 

for aquatic life and human health in the immediate discharge 

zone under baseline future profile. This scope includes plants 

with predicted future air pollution control installations 

identified in the Integrated Planning (IPM) projections for 

the final Mercury and Air Toxics Standards (MATS) rule. 

Generates inputs for Wildlife and Human Health Models. 

Yes 

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