Water Quality Studies
in the
Vicinity of the Washington Aqueduct

Table of Contents

 

EXECUTIVE SUMMARY......................................................

ES-1
1.   INTRODUCTION............................................................

1-1
2.   EFFLUENT FATE AND TRANSPORT MODELING.

2-1
2.1.4   Water Chemistry Data ............................................... 2-5
2.1.5   Particle Size Distribution........................................... 2-7
2.1.6   Plume Surveys at Outfall 003
           (Georgetown Reservoir) ............................................		 2-8
2.1.7   Plume Surveys at Outfall 002
           (Dalecarlia Basin)........................................................		 2-11

2.2      Model Calibration ......................................................

 2-15
2.2.1   Model Grid.................................................................. 2-16

2.2.2   RMA2 Model Development......................................

 2-16

2.2.3   Calibration of Dispersion to the
           Dye Survey Data (RMA4) .........................................

 2-17

2.2.4   Modeling the Suspended Solids Plume (SED2D)..

 2-19
2.3       Suspended Solids Fate and
            Mixing Zone Dilution Factors..................................		 2-23

2.3.1    Suspended Solids Fate at Outfall 002.....................

 2-23
2.3.2    Suspended Solids Fate at Outfall 003..................... 2-25
2.3.3    Mixing Zones.............................................................. 2-27

2.3.4    Effluent Fate and Transport Modeling Summary.

 2-32

2.4       References...................................................................

 2-35
3.         EFFLUENT TOXICITY TESTING ........................... 3-1

3.1       Introduction ...............................................................

 3-1

3.2       Methods and Materials.............................................

 3-2

3.2.1    Sample Receipt...........................................................

 3-2
3.2.2    Test Organisms.......................................................... 3-3
3.2.3    Laboratory Control Waters and
            Control Sediments ....................................................		 3-4

3.2.4    Toxicity Test Operations and Performance...........

 3-4
3.2.4.1 Acute Toxicity Testing.............................................. 3-5

3.2.4.2 Chronic Toxicity Testing...........................................

 3-5
3.2.4.3 Benthic Toxicity Testing........................................... 3-8

3.2.5    Reference Toxicant Tests..........................................

 3-9
3.2.6    Archives....................................................................... 3-9

3.3       Results.........................................................................

 3-9
3.3.1   Acute Toxicity Testing .............................................. 3-9

3.3.2   Chronic Toxicity Testing...........................................

 3-11

3.3.3   Benthic Toxicity Testing............................................

 3-12
3.3.4   Reference Toxicant Testing....................................... 3-12

3.4      Summary and Conclusions.......................................

 3-12
3.5      References ................................................................... 3-13
4.        EFFLUENT CHEMICAL CHARACTERIZATION 4-1

4.1      Existing Aqueduct Effluent Chemistry Data..........

 4-1
4.2      Effluent Chemistry Data Generated by EA............. 4-3
4.3      Historical Potomac River Flows and
           Suspended Sediment Concentrations......................		 4-3
4.3.1   Potomac River Flow Data.......................................... 4-4

4.3.2   Potomac River TSS Data ...........................................

 4-4

4.4      References ...................................................................

 4-5

5.        FISHERIES ...................................................................

 5-1

5.1      Life History Information ...........................................

 5-1

5.1.1   Striped Bass.................................................................

 5-1
5.1.2   White Perch ................................................................. 5-3

5.1.3   American Shad............................................................

 		5-4

5.1.4   Blueback Herring........................................................

 		5-6

5.1.5   Alewife ........................................................................

 5-7

5.1.6   Yellow Perch ...............................................................

 5-9

5.1.7   Smallmouth Bass ........................................................

 5-11

5.1.8   Pumpkinseed..............................................................

 5-12

5.1.9   Bluegill.........................................................................

 5-13

5.1.10 Channel Catfish ..........................................................

 5-14

5.1.11 Brown Bullhead .........................................................

 5-15
5.1.12 Shortnose Sturgeon..................................................... 5-16
5.2      Potential Fish Habitat in the Project Area............... 5-17

5.3      Potential for Sediment-Discharge Impacts
           to Fish Species of Concern.........................................

 5-18

5.4      Potential Discharge Management Scenarios to
           Minimize Impacts to Fish Species of Concern.......

 5-20
5.5      References .................................................................. 5-22
6.        BENTHIC MACROINVERTEBRATE COMMUNITY 6-1

6.1      Methods........................................................................

 6-1

6.2      Results .........................................................................

 6-2
6.2.1   Pre-Discharge Data..................................................... 6-2

6.2.2   Post-Discharge Data ..................................................

 6-4
6.3      Summary and Conclusions....................................... 6-5

6.4      References ...................................................................

 6-7

7.        SUMMARY AND CONCLUSIONS..........................

 7-1
7.1      Effluent Fate and Transport Modeling.................... 7-1
7.2      Toxicity Testing .......................................................... 7-2

7.3      Effluent Chemical Characterization .........................

 7-4

7.4      Fisheries Issues............................................................

 7-4

7.5      Benthic Macroinvertebrate Studies ..........................

 7-5

 

APPENDIX A:
DYE CONCENTRATION AND TURBIDITY DATA AT TRANSECTS
DURING THE 2, 3, 24, AND 25 MAY 2000 PLUME MAPPING SURVEYS

APPENDIX B:
EFFLUENT FATE AND TRANSPORT MODELING

APPENDIX C:
STUDY PLAN FOR WASHINGTON AQUEDUCT WATER QUALITY
STUDIES (24 JUNE 1999), PREPARED BY EA ENGINEERING FOR THE
METROPOLITAN WASHINGTON COUNCIL OF GOVERNMENTS

 

LIST OF FIGURES

 

Number Title
1-1 Study area for the Washington Aqueduct water quality studies.
2.1-1A

Transects used during the bathymetry study.
2.1-1B Transects used during the bathymetry study.

2.1-2

Relationship between TSS and turbidity in water samples collected during the turbidity surveys at Outfalls 002 and 003.
2.1-3

Average dye dilution contours during surveys 2 and 3 of the Outfall 003 plume mapping survey, 2 May 2000.
2.1-4 Maximum TSS concentrations during the turbidity plume mapping surveys at Outfall 003, 3 May 2000.
2.1-5 Dye dilution contours during the Outfall 002 plume mapping survey, 24 May 2000 (1320-1340 hrs.).
2.2-1 Near-field model grid used at Outfalls 002 and 003.
2.2-2 Model grid used in the downstream portion of the Potomac River Model.
2.3-1 The incremental mass associated with suspended sand, floc, and silt, the mass deposited, and the total mass in the system, 25 May 2000, Outfall 002.
2.3-2 Predicted TSS concentrations in the Potomac River at the end of the solids release from Outfall 002, 25 May 2000.
2.3-3 Predicted TSS concentrations in the Potomac River 2 hours after the end of the solids release from Outfall 002, 25 May 2000.
2.3-4 Predicted TSS concentrations in the Potomac River 4 hours after the end of the solids release from Outfall 002, 25 May 2000.
2.3-5A Predicted sediment deposition associated with a clean-out event at Outfall 002, 25 May 2000, upstream.
2.3-5B Predicted sediment deposition associated with a clean-out event at Outfall 002, 25 May 2000, downstream.
2.3-6 The incremental mass associated with suspended sand, floc, and silt, the mass deposited, and the total mass in the system, 3 May 2000, Outfall 003.
2.3-7 Predicted TSS concentrations in the Potomac River at the end of the solids release from Outfall 003, 3 May 2000.
2.3-8 Predicted TSS concentrations in the Potomac River 2 hours after the end of the solids release from Outfall 003, 3 May 2000.
2.3-9 Predicted TSS concentrations in the Potomac River 4 hours after the end of the solids release from Outfall 003, 3 May 2000.
2.3-10 Predicted sediment deposition associated with a clean-out event at Outfall 003, 3 May 2000.
2.3-11 Predicted dilution contours at Outfall 002, 1.132-cms discharge flow, 153-cms river flow.
2.3-12 Predicted dilution contours at Outfall 003, 1.138-cms discharge flow, 153-cms river flow.
4-1 Relationship between suspended solids and Potomac River flow, USGS data at Chain Bridge, 1980-1999.
5-1 Spawning periods for fish species of concern (date-temperature relationship based on mean Potomac River temperatures for the period 1996-1999).
5-2 Aquatic habitat map (in sleeve).
6-1 Locations of the benthic sampling stations in the vicinity of Outfall 003, April and May 2000.
6-2 Potomac River flows (at Little Falls) for the benthic community study.

 

LIST OF TABLES
Number Title
2.1-1

Transects used during the dye and turbidity plume mapping surveys at Outfalls 002 and 003.
2.3-1

Suspended and deposited solids mass for the sand, floc, and silt particle classes present in the Aqueduct model domain, 25 May 2000, Outfall 002.
2.3-2 Suspended and deposited solids mass for the sand, floc, and silt particle classes present in the Aqueduct model domain, 3 May 2000, Outfall 003.

2.3-3

 Downstream distance to dilution contours and 1-hour average dilution at Outfall 002 for a range of Potomac River flows, Dalecarlia Basin.
2.3-4

Plume width and cross-sectional area at transect 3-m downstream of Outfall 002, Dalecarlia Basin.
2.3-5 Downstream distance to dilution contours and 1-hour average dilution at Outfall 003 for a range of Potomac River flows, Georgetown Reservoir.
2.3-6 Plume width and cross-sectional area at a transect 90-m downstream of Outfall 003, Georgetown Reservoir.
3-1 Summary of sample collection and receipt data for samples from Washington Aqueduct.
3-2 Summary of acute toxicity test results—Washington Aqueduct.
3-3

Summary of chronic toxicity results—Washington Aqueduct.
3-4

Summary of benthic toxicity test results—Washington Aqueduct.
4-1a Summary of chemistry monitoring data by analyte for each Dalecarlia Basin for the years 1997-2001.

4-1b

Summary of chemistry monitoring data by analyte for each Georgetown Basin for the years 1997-2001.
4-2a Average yearly concentrations measured during chemistry monitoring for each Dalecarlia Basin from 1997-2001.

4-2b

Average yearly concentrations measured during chemistry monitoring for each Georgetown Basin from 1997-2001.

4-3

Analytical chemistry results obtained from effluent toxicity testing program.

4-4

Frequency distribution of daily USGS Potomac River flows at Little Falls, 1980-1999.
4-5 Frequency distribution of suspended sediment concentration and load.

6-1

Number of benthic macroinvertebrates collected on 27 April 2001 (pre-discharge) classified by major taxonomic group.
6-2 Number of benthic macroinvertebrates collected on 8 May 2000 (post-discharge) classified by major taxonomic group.
6-3 Number of benthic macroinvertebrates collected on 27 April 2000 (pre-discharge).
6-4 Number of benthic macroinvertebrates collected on 8 May 2000 (post-discharge).

 

LIST OF PHOTOS

Number Title
6-1

Hester-Dendy units on concrete block before placement.
6-2

Hester-Dendy marking at DS-2, (3-10-00).
6-3 Hester-Dendy upstream location, (5-8-00).

6-4

6-4 Gentle H-D removal at DS-3, (5-8-00).