UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

 WASHINGTON D.C. 20460

OFFICE OF THE ADMINISTRATOR

SCIENCE ADVISORY BOARD

July 12, 2011

EPA-SAB-11-009

The Honorable Lisa P. Jackson

Administrator

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, N.W.

Washington, D.C. 20460

Subject: Efficacy of Ballast Water Treatment Systems: a Report by the EPA Science 

Advisory Board

Dear Administrator Jackson:

This Advisory report responds to a request from EPA’s Office of Water (OW) for EPA’s Science 

Advisory Board (SAB) to provide advice on technologies and systems to minimize the impacts of 

invasive species in vessel ballast water discharge. Vessel ballast water discharges are a major source of 

non-indigenous species introductions to marine, estuarine, and freshwater ecosystems of the United 

States. Ballast water discharges are regulated by the EPA under authority of the Clean Water Act 

(CWA) and by the United States Coast Guard (USCG) under authority of the National Invasive Species 

Act (NISA). At present, federal requirements for managing ballast water discharges rely primarily on 

ballast water exchange; however changes to federal ballast water regulations are under consideration. On 

August 28, 2009, the USCG proposed revising their existing rules to establish numeric concentrationbased limits for live organisms in ballast water. The proposed rule would initially require compliance 

with a “Phase 1 standard” that has the same concentration limits as the International Maritime 

Organization (IMO) D-2 standard and subsequently require compliance with a more stringent “Phase 2 

standard.” 

The EPA’s existing CWA general permit for vessels will expire on Dec. 19, 2013. In its revisions to the 

vessel general permit, the EPA is considering numeric standards that limit the number of live organisms 

in discharged ballast water. To assist in this, OW requested in their charge questions that the SAB 

provide advice regarding the effectiveness of existing technologies for shipboard treatment of vessel 

ballast water, how these technologies might be improved in the future, and how to overcome limitations 

in existing data. This assessment was conducted by the SAB’s Ecological Processes and Effects 

Committee (EPEC) as augmented with additional Panel members having expertise in ballast water 

issues and water treatment (collectively referred to as the Panel). 

To prepare this report, the Panel reviewed a “Background and Issues Paper” prepared by OW and USCG 

(June 2010) as well as information on 51 existing or developmental ballast water management systems 

(BWMS) provided by OW and the public, although detailed data were available for only 15 BWMS. 
Hence this assessment is based on information available at a given point in time. The Panel used this 

information as the source material for conducting its assessment of ballast water treatment performance 

and, as requested by OW, used the numeric limits proposed by USCG and by some states as

performance benchmarks.

In response to the four specific charge questions, the Panel’s findings were that:

(1) Based on the information provided, five of 34 categories of assessed BWMS achieved 

reductions in organism concentrations sufficient to comply with the first standard proposed by

the USCG (i.e., the ‘Phase 1’ standard). Although current test methods and detection limits 

preclude a complete statistical assessment of whether a BWMS meets any standard more 

stringent than Phase 1, the Panel concluded that none of the assessed BWMS can meet a standard 

that is 100 or 1000 times more stringent. Furthermore, it is not reasonable to assume that the 

assessed BWMS are able to reliably meet or closely approach a “no living organism” standard. 

(2) Current BWMS are based on reasonable engineering designs and standard water treatment 

processes, but significant difficulties are encountered in adapting standard water treatment 

technologies to shipboard operation (e.g., range of environmental conditions encountered, vessel 

operational parameters, and vessel design characteristics). 

(3) Reasonable changes in existing BWMS are likely to result in incremental improvements, but 

are not likely to lead to 100 or 1000 times further reductions in organism concentrations. 

Because of technological, logistical, and personnel constraints imposed by shipboard operations, 

wholly new systems need to be developed to meet proposed standards that are 100 or 1000 times 

more stringent than Phase 1. The Panel provided some ideas on designs for potential new 

systems, recognizing that time will be required to develop and test new approaches to determine 

their practicality and cost. 

(4) The Panel reviewed the many limitations associated with existing data for ballast water 

treatment performance and provided advice on how to correct these limitations in future

assessments; the Panel recommends using improved testing protocols for verifying discharge 

concentrations, exploring the use of surrogate performance measures, and developing reliable 

protocols for compliance monitoring. 

However, the Panel’s overarching recommendation is that the EPA adopt a risk-based approach to 

minimize the impacts of invasive species in vessel ballast water discharge rather than relying solely on 

numeric standards for discharges from shipboard BWMS. The Panel found that insufficient attention has 

been given to integrated sets of practices and technologies that could be used to systematically advance 

ballast water management. These practices include managing ballast uptake to reduce the presence of 

invasive species, reducing invasion risk through operational adjustments and changes in ship design to 

reduce or eliminate the need for ballast water, development of voyage-based risk and/or hazard 

assessments, and treatment of ballast water in onshore reception facilities. The Panel recommended that 

a comprehensive analysis be done to compare biological effectiveness, cost, logistics, operations and 

safety associated with shipboard BWMS and onshore reception facilities. 
The SAB appreciates the opportunity to provide the EPA with advice on this important topic. We look 

forward to receiving the Agency’s response.

Sincerely,

/Signed/ /Signed/

Dr. Deborah L. Swackhamer Dr. Judith L. Meyer

Chair Chair

Science Advisory Board SAB Ballast Water Advisory Panel 

Enclosure
i

 

NOTICE

This report has been written as part of the activities of the EPA Science Advisory Board (SAB), a public 

advisory group providing extramural scientific information and advice to the Administrator and other 

officials of the Environmental Protection Agency. The SAB is structured to provide balanced, expert 

assessment of scientific matters related to problems facing the Agency. This report has not been 

reviewed for approval by the Agency and, hence, the contents of this report do not necessarily represent 

the views and policies of the Environmental Protection Agency, nor of other agencies in the Executive 

Branch of the Federal government, nor does mention of trade names of commercial products constitute a 

recommendation for use. Reports of the SAB are posted on the EPA website at 

http://www.epa.gov/sab.
ii

U.S. Environmental Protection Agency

Science Advisory Board

Ecological Processes and Effects Committee 

Augmented for the Ballast Water Advisory

(Ballast Water Advisory Panel)

CHAIR

Dr. Judith L. Meyer, Professor Emeritus, Odum School of Ecology, University of Georgia, Lopez 

Island, WA

MEMBERS

Dr. E. Fred Benfield, Professor of Ecology, Department of Biological Sciences, Virginia Tech, 

Blacksburg, VA

Dr. G. Allen Burton, Professor and Director, Cooperative Institute for Limnology and Ecosystems 

Research, School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI

Dr. Peter Chapman, Principal and Senior Environmental Scientist, Environmental Sciences Group, 

Golder Associates Ltd, Burnaby, BC, Canada

Dr. William Clements, Professor, Department of Fish, Wildlife, and Conservation Biology, Colorado 

State University, Fort Collins, CO

Dr. Loveday Conquest, Professor, School of Aquatic and Fishery Sciences, University of Washington, 

Seattle, WA

Dr. Robert Diaz, Professor, Department of Biological Sciences, Virginia Institute of Marine Science, 

College of William and Mary, Gloucester Pt., VA

Dr. Wayne Landis, Professor and Director, Department of Environmental Toxicology, Institute of 

Environmental Toxicology, Huxley College of the Environment, Western Washington University, 

Bellingham, WA

Dr. Thomas W. La Point, Professor, Department of Biological Sciences, University of North Texas, 

Denton, TX

Dr. Amanda Rodewald, Associate Professor, School of Environment and Natural Resources, The Ohio 

State University, Columbus, OH

Dr. James Sanders, Director and Professor, Skidaway Institute of Oceanography, Savannah, GA

AUGMENTED PANEL MEMBERS

Dr. JoAnn Burkholder, Professor, Department of Plant Biology, Center for Applied Aquatic Ecology, 

North Carolina State University, Raleigh, NC
iii

Dr. Andrew N. Cohen1, Director, Center for Research on Aquatic Bioinvasions, Richmond, CA

Dr. Fred Dobbs, Professor and Graduate Program Director, Ocean, Earth and Atmospheric Sciences, 

College of Sciences, Old Dominion University, Norfolk, VA

Dr. Lisa Drake, Physical Scientist, Center for Corrosion Science and Engineering, Naval Research 

Laboratory, Key West, FL

Dr. Charles Haas, L.D. Betz Professor of Environmental Engineering, Civil, Architectural and 

Environmental Engineering, College of Engineering, Drexel University, Philadelphia, PA

Mr. Edward Lemieux, Director, Center for Corrosion Science Engineering, Naval Research 

Laboratory, Washington, DC

Dr. David Lodge, Professor, Biological Sciences, University of Notre Dame, Notre Dame, IN

Mr. Kevin Reynolds, Senior Marine Engineer, The Glosten Associates, Seattle, WA

Dr. Mario Tamburri, Associate Professor, Chesapeake Biological Laboratory, Maritime 

Environmental Resource Center, University of Maryland Center for Environmental Science, Solomons, 

MD

Dr. Nicholas Welschmeyer, Professor of Oceanography, Moss Landing Marine Laboratories, San Jose 

State University, Moss Landing, CA

SCIENCE ADVISORY BOARD STAFF

Ms. Iris Goodman, Designated Federal Officer, U.S. Environmental Protection Agency, Washington, 

DC

 1 Dr. Cohen did not concur with the final draft report submitted to the chartered SAB for their quality review and approval. 
iv

U.S. Environmental Protection Agency

Science Advisory Board

CHAIR

Dr. Deborah L. Swackhamer, Professor and Charles M. Denny, Jr. Chair in Science, Technology and 

Public Policy, Hubert H. Humphrey School of Public Affairs and Co-Director of the Water Resources 

Center, University of Minnesota, St. Paul, MN

SAB MEMBERS

Dr. David T. Allen, Professor, Department of Chemical Engineering, University of Texas, Austin, TX

Dr. Claudia Benitez-Nelson, Full Professor and Director of the Marine Science Program, Department 

of Earth and Ocean Sciences , University of South Carolina, Columbia, SC

Dr. Timothy J. Buckley, Associate Professor and Chair, Division of Environmental Health Sciences, 

College of Public Health, The Ohio State University, Columbus, OH

Dr. Patricia Buffler, Professor of Epidemiology and Dean Emerita, Department of Epidemiology, 

School of Public Health, University of California, Berkeley, CA

Dr. Ingrid Burke, Director, Haub School and Ruckelshaus Institute of Environment and Natural 

Resources, University of Wyoming, Laramie, WY

Dr. Thomas Burke, Professor, Department of Health Policy and Management, Johns Hopkins 

Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD

Dr. Terry Daniel, Professor of Psychology and Natural Resources, Department of Psychology, School 

of Natural Resources, University of Arizona, Tucson, AZ

Dr. George Daston, Victor Mills Society Research Fellow, Product Safety and Regulatory Affairs, 

Procter & Gamble, Cincinnati, OH

Dr. Costel Denson, Managing Member, Costech Technologies, LLC, Newark, DE

Dr. Otto C. Doering III, Professor, Department of Agricultural Economics, Purdue University, W. 

Lafayette, IN

Dr. David A. Dzombak, Walter J. Blenko, Sr. Professor of Environmental Engineering, Department of 

Civil and Environmental Engineering, College of Engineering, Carnegie Mellon University, Pittsburgh, 

PA

Dr. T. Taylor Eighmy, Vice President for Research, Office of the Vice President for Research, Texas 

Tech University, Lubbock, TX

Dr. Elaine Faustman, Professor and Director, Institute for Risk Analysis and Risk Communication, 

School of Public Health, University of Washington, Seattle, WA
v

Dr. John P. Giesy, Professor and Canada Research Chair, Veterinary Biomedical Sciences and 

Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Dr. Jeffrey K. Griffiths, Professor, Department of Public Health and Community Medicine, School of 

Medicine, Tufts University, Boston, MA

Dr. James K. Hammitt, Professor, Center for Risk Analysis, Harvard University, Boston, MA

Dr. Bernd Kahn, Professor Emeritus and Associate Director, Environmental Radiation Center, Georgia 

Institute of Technology, Atlanta, GA

Dr. Agnes Kane, Professor and Chair, Department of Pathology and Laboratory Medicine, Brown 

University, Providence, RI

Dr. Madhu Khanna, Professor, Department of Agricultural and Consumer Economics, University of 

Illinois at Urbana-Champaign, Urbana, IL

Dr. Nancy K. Kim, Senior Executive, Health Research, Inc., Troy, NY

Dr. Kai Lee, Program Officer, Conservation and Science Program, David & Lucile Packard Foundation, 

Los Altos, CA (Affiliation listed for identification purposes only)

Dr. Cecil Lue-Hing, President, Cecil Lue-Hing & Assoc. Inc., Burr Ridge, IL

Dr. Floyd Malveaux, Executive Director, Merck Childhood Asthma Network, Inc., Washington, DC

Dr. Lee D. McMullen, Water Resources Practice Leader, Snyder & Associates, Inc., Ankeny, IA

Dr. Judith L. Meyer, Professor Emeritus, Odum School of Ecology, University of Georgia, Lopez 

Island, WA

Dr. James R. Mihelcic, Professor, Civil and Environmental Engineering, University of South Florida, 

Tampa, FL

Dr. Jana Milford, Professor, Department of Mechanical Engineering, University of Colorado, Boulder, 

CO

Dr. Christine Moe, Eugene J. Gangarosa Professor, Hubert Department of Global Health, Rollins 

School of Public Health, Emory University, Atlanta, GA

Dr. Horace Moo-Young, Dean and Professor, College of Engineering, Computer Science, and 

Technology, California State University, Los Angeles, CA

Dr. Eileen Murphy, Grants Facilitator, Ernest Mario School of Pharmacy, Rutgers University, 

Piscataway, NJ
vi

Dr. Duncan Patten, Research Professor, Hydroecology Research Program, Department of Land 

Resources and Environmental Sciences, Montana State University, Bozeman, MT

Dr. Stephen Polasky, Fesler-Lampert Professor of Ecological/Environmental Economics, Department 

of Applied Economics, University of Minnesota, St. Paul, MN

Dr. Arden Pope, Professor, Department of Economics, Brigham Young University, Provo, UT

Dr. Stephen M. Roberts, Professor, Department of Physiological Sciences, Director, Center for 

Environmental and Human Toxicology, University of Florida, Gainesville, FL

Dr. Amanda Rodewald, Professor of Wildlife Ecology, School of Environment and Natural Resources, 

The Ohio State University, Columbus, OH

Dr. Jonathan M. Samet, Professor and Flora L. Thornton Chair, Department of Preventive Medicine, 

University of Southern California, Los Angeles, CA

Dr. James Sanders, Director and Professor, Skidaway Institute of Oceanography, Savannah, GA

Dr. Jerald Schnoor, Allen S. Henry Chair Professor, Department of Civil and Environmental 

Engineering, Co-Director, Center for Global and Regional Environmental Research, University of Iowa, 

Iowa City, IA

Dr. Kathleen Segerson, Philip E. Austin Professor of Economics , Department of Economics, 

University of Connecticut, Storrs, CT

Dr. Herman Taylor, Director, Principal Investigator, Jackson Heart Study, University of Mississippi 

Medical Center, Jackson, MS

Dr. Barton H. (Buzz) Thompson, Jr., Robert E. Paradise Professor of Natural Resources Law at the 

Stanford Law School and Perry L. McCarty Director, Woods Institute for the Environment, Stanford 

University, Stanford, CA

Dr. Paige Tolbert, Professor and Chair, Department of Environmental Health, Rollins School of Public 

Health, Emory University, Atlanta, GA

Dr. John Vena, Professor and Department Head, Department of Epidemiology and Biostatistics, 

College of Public Health, University of Georgia, Athens, GA

Dr. Thomas S. Wallsten, Professor and Chair, Department of Psychology, University of Maryland, 

College Park, MD

Dr. Robert Watts, Professor of Mechanical Engineering Emeritus, Tulane University, Annapolis, MD

Dr. R. Thomas Zoeller, Professor, Department of Biology, University of Massachusetts, Amherst, MA
vii

SCIENCE ADVISORY BOARD STAFF

Dr. Angela Nugent, Designated Federal Officer, U.S. Environmental Protection Agency, Washington, 

DC

Ms. Stephanie Sanzone, Designated Federal Officer, U.S. Environmental Protection Agency, 

Washington, DC
viii

Table of Contents

1. EXECUTIVE SUMMARY ............................................................................................................................................1

2. INTRODUCTION ..........................................................................................................................................................9

2.1. EPA’s Charge to the SAB......................................................................................................................................... 9

2.2. SAB’s Review Process........................................................................................................................................... 11

2.3. Regulatory Frameworks for Ballast Water Management ..................................................................................... 11

2.3.1. U.S. Federal rules.............................................................................................................................................11

2.3.2. Other Regulatory Frameworks ........................................................................................................................12

2.3.3. Glossary of Terms Used ...................................................................................................................................13

2.4. Applying Risk Assessment Principles to Ballast Water Management ................................................................... 16

2.4.1. Risk Assessment of Nonindigenous Species ....................................................................................................16

2.4.2. Ballast Water Management Goals and the Decision Making, Risk Assessment Context ................................19

3. STATISTICS AND INTERPRETATION..................................................................................................................22

3.1. Introduction......................................................................................................................................................... 22

3.2. Assessing Whether Ballast Water Standards Can Be Met — The Statistics of Sampling ....................................... 22

3.2.1. The Poisson Distribution..................................................................................................................................23

3.2.2. Spatially Aggregated Populations – Negative Binomial Distributions .............................................................27

3.3. Interactive Effects................................................................................................................................................ 28

3.4. Certainty of Results.............................................................................................................................................. 28

3.5. Conclusions.......................................................................................................................................................... 29

4. PERFORMANCE OF SHIPBOARD SYSTEMS WITH AVAILABLE EFFLUENT TESTING DATA ............30

4.1. EPA’s Charge Questions....................................................................................................................................... 30

4.2. Assessment Process............................................................................................................................................. 30

4.3. Assessing the Reliability of Existing Data ............................................................................................................. 30

4.4. Assessing the Ability of BWMS to Meet Discharge Standards.............................................................................. 31

4.5. Assessment Results.............................................................................................................................................. 36

4.6. Response to Charge Question 1 ........................................................................................................................... 36

4.7. Response to Charge Question 2 ........................................................................................................................... 38

4.8. Environmental Effects and Vessel Applications: Additional Constraints and Considerations that Influence

BWMS Performance ............................................................................................................................................ 39
ix

5. SYSTEM DEVELOPMENT........................................................................................................................................42

5.1. Introduction......................................................................................................................................................... 42

5.2. Improving the Performance of Existing Systems.................................................................................................. 42

5.2.1. Combination Technologies..............................................................................................................................43

5.2.2. UV Radiation....................................................................................................................................................44

5.2.3. Mechanical Separation and Cavitation............................................................................................................45

5.2.4. Deoxygenation.................................................................................................................................................45

5.2.5. Oxidant-Based Systems ...................................................................................................................................46

5.3. Principal Technological Constraints ..................................................................................................................... 49

5.3.1. Operational Challenges on Working Merchant Vessels...................................................................................50

5.3.2. Idealized Designs for BWMS ............................................................................................................................53

5.4. Recommendations for Addressing Impediments and Constraints........................................................................ 56

5.5. Impediments Based on Organism Type................................................................................................................ 57

5.6. Sterilization of Ballast Water Discharge ............................................................................................................... 57

6. LIMITATIONS OF EXISTING STUDIES AND REPORTS...................................................................................58

6.1. EPA’s Charge Question......................................................................................................................................... 58

6.2. Testing Shipboard Treatment Systems: Protocols, Analysis, and Reporting Practices that Could Be Improved.... 58

6.2.1 Confusion of Research and Development and Certification Testing ...............................................................58

6.2.2 Lack of Standardized Testing Protocols...........................................................................................................59

6.2.3. Compromises Necessary Because of Practical Constraints in Sampling and Available Methods....................70

6.2.4. Testing Shipboard Treatment Systems: Inherent Mismatch between Viability Standard and Practical

Protocols.........................................................................................................................................................75

6.3. Approaches to Compliance/Enforcement of Ballast Water Regulations and Potential Application to Technology 

Testing................................................................................................................................................................ 79

6.4. Reception Facilities as an Alternative to Shipboard Treatment............................................................................ 80

6.4.1. Potential of Reception Facilities to Cost Effectively Meet Higher Standards..................................................80

6.4.2. Challenges to Widespread Adoption of Reception Facilities in the U.S...........................................................85

6.5. Approaches Other than Ballast Water Treatment................................................................................................ 88

6.5.1. Managing Ballast Uptake.................................................................................................................................88

6.5.2. Mid-ocean Exchange........................................................................................................................................89

6.5.3. Reducing or Eliminating Ballast Water Discharge Volumes.............................................................................89

6.5.4. Temporal and Spatial Patterns ........................................................................................................................91

6.5.5. Combined Approaches ....................................................................................................................................91

6.6. Risk Management Approaches to Reduce Invasion Risk: Hazard Analysis and Critical Control Points (HAACP).... 92

6.7. Summary and Recommendations........................................................................................................................ 95

6.7.1. Principal Limitations of Available Data and Protocols.....................................................................................95

6.7.2. Alternatives to Shipboard Treatment of Ballast Water ...................................................................................95

6.7.3. Recommendations to Overcome Present Limitations.....................................................................................96

REFERENCES ...............................................................................................................................................................R-1
x

APPENDIX A: DOCUMENTS ON BALLAST WATER TECHNOLOGIES PROVIDED TO THE PANEL....A-1

APPENDIX B: LITERATURE REVIEW OF RECEPTION FACILITY STUDIES .............................................B-1

APPENDIX C: FURTHER INFORMATION ON STATISTICS AND INTERPRETATION ..............................C-1
1

1. EXECUTIVE SUMMARY

Vessel ballast water discharges are a primary source of introductions of nonindigenous species and 

potentially harmful pathogens to marine, estuarine, and freshwater ecosystems of the United States. At 

present, federal requirements for managing ballast water discharges rely primarily on ballast water 

exchange. However, the U.S. Coast Guard (USCG) has proposed numeric concentration-based limits 

for live organisms in ballast water that would initially require compliance with a “Phase 1 standard” that 

has the same concentration limits as the International Maritime Organization (IMO) D-2 standard and 

subsequently require compliance with a more stringent “Phase 2 standard.” In addition, the U.S. 

Environmental Protection Agency is considering numeric standards that limit the number of live 

organisms in discharged ballast water in its revision of the Vessel General Permit.

This Advisory report responds to a request from the EPA Office of Water (OW) for EPA’s Science 

Advisory Board (SAB) to provide advice on technologies and systems to minimize the impacts of 

invasive species in vessel ballast water discharge. More specifically, the SAB was requested to provide 

review and advice regarding whether existing shipboard treatment technologies can reach specified 

concentrations of organisms in vessel ballast water, how these technologies might be improved in the 

future, and how to overcome limitations in existing data. To conduct the assessment, the SAB’s 

Ecological Processes and Effects Committee (EPEC) was augmented with additional Panel members 

(Ballast Water Advisory Panel, or “Panel”) having expertise in ballast water issues, marine engineering,

and engineering treatment technologies. 

In addition to the SAB assessment of ballast water management systems (BWMS), the EPA and the 

USCG commissioned the National Academy of Sciences (NAS) to conduct a complementary study2 that 

assesses the risk of successful invasions as a function of different concentrations of organisms in ballast 

water discharges. Therefore, this SAB Advisory does not address the relationship between the various

concentrations of organisms as described in proposed standards and the likelihood of invasions or the 

potential effects of pathogens. Rather, in this report, “effectiveness” refers to how well a technology 

may meet a given numeric concentration limit for organisms, not to how well the technology may 

protect the environment. Similarly, phrases such as “meets more stringent” or “meets less stringent” 

proposed standards are used as descriptive conclusions and do not represent performance 

recommendations. 

To prepare this Advisory report, the Panel reviewed a “Background and Issue Paper” written by EPA’s 

OW and USCG (Albert et al. 2010). This paper provided an overview of information about major 

categories of shipboard ballast water treatment technologies and presented proposed ballast water 

discharge standards drawn from international sources, the USCG, and nine states. In addition, EPA’s 

OW and the public identified information on 51 existing or developmental ballast water treatment 

technologies, although detailed data were available for only 15 specific BWMS. The Panel used this 

information as the source material for its assessment of ballast water treatment performance and, as 

requested by the EPA, used proposed ballast water discharge standards as the performance benchmarks. 

 2 Assessing the Relationship Between Propagule Pressure and Invasion Risk in Ballast Water, 6/2/2011, 

http://www.nap.edu/catalog.php?record_id=13184)
2

Regulatory context 

Ballast water discharges are regulated by EPA under authority of the Clean Water Act (CWA) and by 

the USCG under authority of the National Invasive Species Act (NISA). In December 2008, EPA issued 

a Vessel General Permit (VGP) for discharges incidental to the normal operation of commercial vessels, 

including ballast water discharges. The VGP sets effluent limits for ballast water that rely on “best 

management practices” (primarily use of ballast water exchange, or BWE) and do not include a numeric 

discharge limit. The VGP will expire on Dec. 19, 2013. For subsequent iterations of the VGP, the EPA 

has stated its intention to establish best available technology standards for the treatment of ballast water, 

once such technologies are shown to be commercially available and economically achievable. 

Existing USCG rules governing ballast water also primarily rely on BWE. In August 2009, the USCG 

proposed revisions to their existing rules to establish numeric concentration-based limits for viable 

organisms in ballast water. The proposed USCG rule would initially require compliance with a “Phase 

1” standard, and, if a practicability review shows it is feasible, it would be followed by a “Phase 2” 

standard that sets concentration limits at 1000 times more stringent than Phase 1 standards for viable 

organisms >10 μm in minimum dimension. Phase 2 standards also set limits on the discharge 

concentration for bacteria and viruses. Neither Phase 1 nor Phase 2 standards have been finalized. The 

USCG Phase 1 standards have essentially the same concentration limits as those adopted in 2004 by the 

International Maritime Organization’s (IMO) International Convention for the Control and Management 

of Ships’ Ballast Water and Sediments; thus both standards are often referred to as the “D-2/ Phase 1 

standards.” The U.S. is not a Party to the Convention, nor has the Convention yet entered into force. 

However, manufacturers of BWMS have generally designed their equipment to meet these IMO D-2 

standards. 

Ballast water management should be implemented using a risk-based systems approach 

The Panel recommends that any ballast water management strategy to decrease the rate of successful 

invasions by nonindigenous species or introduction of pathogens be part of an overall risk-based 

management plan that includes methods to reduce invasion events, process and environmental 

monitoring, containment, and eradication. Emphasis only on one aspect, the initial introduction of 

organisms, is not likely to reduce the risk of invasions as effectively or as cost-efficiently as a risk 

assessment approach that considers all the stages of the invasion process including survival after 

introduction. Decisions on approaches to ballast water management should be viewed in the context of 

risk management and should: (1) recognize the stochastic and non-linear nature of the invasion process, 

(2) clearly define the management goals, and (3) evaluate the effectiveness of BWMS within the context 

of other sources of nonindigenous species and other organisms found on the vessel and in the treatment 

system, and with respect to specific receiving habitats. 

Rigorous sampling and statistical verification of performance is essential 

The Panel was asked to respond to charge questions that focused primarily on whether test data 

demonstrated that BWMS met or “closely approached” proposed standards for discharge and whether 

they did so “credibly” and “reliably.” As benchmarks for performance, the Panel was asked to consider 

proposed numerical standards as well as narrative descriptions such as “no living organisms,” 

“sterilization,” and “zero or near zero” discharge. In order to place its assessments of treatment 

performance in appropriate scientific context, the Panel first had to consider statistical and sampling 
3

issues. While “zero detectable discharge” might initially seem a desirable standard, it is not statistically 

verifiable. Further, verification of standards that set very low organism concentrations may require water 

samples that are too large to be logistically feasible. However, when small sample volumes are used, the 

probability of detecting an organism is low even when the actual organism concentration is relatively 

high. These errors depend on the sample volume collected, and the relative errors are much larger for 

small sample volumes.

A well-defined, rigorous sampling protocol is necessary to assess the effectiveness of BWMS at meeting 

different standards. These sampling protocols should include consideration of the spatial distribution of 

plankton in ballast water. The Poisson distribution is recommended as the model for statistical analysis 

of treated water samples. 

The Panel also concludes that the D-2/Phase 1 performance standards for discharge quality are currently 

measurable, based on data from land-based and shipboard testing. However, current methods (and 

associated detection limits) prevent testing of BWMS to any standard more stringent than D-2/Phase 1 

and make it impracticable for verifying a standard 100 or 1000 times more stringent. New or improved 

methods will be required to increase detection limits sufficiently to statistically evaluate a standard 10x 

more stringent than IMO D-2/Phase 1; such methods may be available in the near future. These 

conclusions pertain to evaluating data from land-based and shipboard testing, although the same 

statistical theory and practice applies to compliance testing by port state control officers.

Charge question 1: Performance of shipboard systems with available effluent testing data

a. For the shipboard systems with available test data, which have been evaluated with sufficient rigor to 

permit a credible assessment of performance capabilities in terms of effluent concentrations achieved 

(living organisms/unit of ballast water discharged or other metric)?

Evaluations of technologies are necessarily based on performance information for a given point in time 

and the development and manufacture of ballast water treatment systems is a dynamic industry. For this 

assessment, the Panel reviewed information provided by EPA’s Office of Water and the public. This 

information included peer-reviewed articles and publications; information provided directly from 

individual manufacturers of BWMS (some included data reports, others provided only Type Approval 

certificates); and public dossiers submitted to the IMO Group of Experts on the Scientific Aspects of 

Marine Environmental Protection (GESAMP). This information was prepared or published prior to May, 

2010. However, the majority of the documents were from 2008 to 2010, reflecting growth in the BWMS 

industry. While other BWMS may exist, the Panel considered only those for which information was 

provided.

From this information, the Panel identified 51 individual BWMS, which can be grouped into 34 

categories of treatment technologies. Of the 51 BWMS identified, the Panel concluded that test data and 

other information for 15 individual BWMS were credible and sufficient to permit an assessment of 

performance capabilities. Of these 15 BWMS, nine systems (representing individual configurations of 

five different categories of BWMS) achieved significant reductions in organism concentrations, and 

were able to comply with the Phase 1 standard. These five categories of BWMS technologies are: 

(1) Deoxygenation + cavitation; (2) Filtration + chlorine dioxide; (3) Filtration + UV; (4) Filtration + 

UV + TiO2; and (5) Filtration + electro-chlorination.
4

b. For those systems identified in (1a), what are the discharge standards that the available data credibly 

demonstrate can be reliably achieved? Furthermore, do data indicate that certain systems (as tested) 

will not be able to reliably reach any or all of the discharge standards shown in that table?

The Panel concluded that the same five BWMS categories (listed above) have been demonstrated to 

meet the IMO D-2 discharge standard, when tested under the IMO certification guidelines, and will 

likely meet USCG Phase 1 standards, if tested under EPA’s more detailed Environmental Technology 

Verification (ETV) Protocol (U.S. EPA 2010). The Panel acknowledges the significant achievement of 

several existing BWMS to effectively and reliably remove living organisms from ballast water under the 

challenging conditions found on active vessels.

The detection limits for currently available test methods preclude a complete statistical assessment of 

whether BWMS can meet standards more stringent than IMO D-2/Phase 1. However, based on the 

available testing data, it is clear that while five types of BWMS are able to reach IMO D-2/Phase 1, 

none of the systems evaluated by the Panel performed at 100 times or 1000 times the Phase 1 standard. 

c. For those systems identified in (1a), if any of the system tests detected “no living organisms” in any 

or all of their replicates, is it reasonable to assume the systems are able to reliably meet or closely 

approach a “no living organism” standard based on their engineering design and treatment processes? 

The Panel concluded that it is not reasonable to assume that BWMS are able to reliably meet or closely 

approach a “no living organism” standard. Available data demonstrate that current BWMS do not 

achieve sterilization or the complete removal of all living organisms. 

Charge question 2: Potential performance of shipboard systems without reliable testing data

Based on engineering design and treatment processes used, and shipboard conditions/constraints, what 

types of ballast water treatment systems can reasonably be expected to reliably achieve any of the 

proposed standards, and if so, by what dates? Based on engineering design and treatment processes 

used, are there systems which conceptually would have difficulty meeting any or all of the proposed 

discharge standards?

The Panel found that nearly all of the 51 BWMS evaluated are based on reasonable engineering designs 

and treatment processes, and most are adapted from long-standing water treatment approaches. 

However, the lack of detailed information on the great majority of BWMS precludes an assessment of 

limitations in meeting any or all discharge standards. In particular, the Panel determined that the 

following data are essential to future assessments: documentation that test protocols were followed; full 

reporting of all test results; and documentation that rigorous QA/QC methods were followed. 

Although several BWMS appear to safely and effectively meet IMO D-2/Phase 1 discharge standards, 

the Panel notes that factors beyond mechanical and biological efficacy need to be considered as BWMS 

technology matures. Several parameters will affect the performance or applicability of individual 

BWMS to the wide variety of vessel types that carry ballast water. These include environmental 

parameters (e.g., temperature and salinity), operational parameters (e.g., ballast volumes and holding 

times), and vessel design characteristics (e.g., ballast volume and unmanned barges).
5

Charge question 3: System development

a. For those systems identified in questions 1 a. and 2, are there reasonable changes or additions to 

their treatment processes which can be made to the systems to improve performance?

The Panel defined “reasonable changes” as moderate adjustments that do not fundamentally alter the 

treatment process. Based on information from available test results, such moderate adjustment could be 

made to treatment processes, although it may add costs and engineering complexity. Examples of 

moderate adjustments are:

• Deoxygenation + cavitation. It may be possible to reduce the time needed to reach severe 

hypoxia, to increase holding time under severe hypoxia, and to increase the degree of 

cavitation and physical/mechanical disruption of organisms.

• Mechanical separation + oxidizing agent. These systems could be optimized by improving 

mechanical separation, increasing concentration and contact time for oxidizing agents, and 

adjusting other water chemistry parameters (e.g., pH) to increase oxidizing agent efficacy. 

• Mechanical separation + UV. These systems could be optimized by improved mechanical 

separation and by increasing UV contact time and dosage. 

The Panel concludes that moderate adjustments or changes to existing combination technologies are 

expected to result in only incremental improvements. Reaching the Phase 2 standard, or even 100x IMO 

D-2/ Phase1, would require wholly new treatment systems. Such new systems likely would use new 

technological devices, including those drawn from the water treatment industry; employ multistage 

treatment processes; emphasize technological process controls and multiple monitoring points; include 

physical barriers to minimize the potential for cross-contamination of the system; and become part of an 

integrated ballast water management effort. These new approaches likely will achieve higher 

performance, but will require time to develop and test in order to determine their practicality and cost. 

b. What are the principal technological constraints or other impediments to the development of ballast 

water treatment technologies for use onboard vessels to reliably meet any or all of the discharge 

standards?

Existing BWMS have been developed within the context of typical marine vessel constraints, including 

restrictions on size, weight, and energy demands. The primary impediments to the ability of shipboard 

systems to meet stringent discharge standards are that treatment processing plants likely will be large, 

heavy, and energy intensive—many existing vessels may be unable to overcome these barriers through 

retrofitting BWMS. Meeting more stringent performance standards may require a fundamental shift in 

how ballast water is managed. 

Existing and potential BWMS share several common impediments to development: (1) The focus has 

been on engineering the technology with less attention to equally important issues such as training, 

operation, maintenance, repair, and monitoring. (2) Without an established compliance monitoring and 

enforcement regime to guide design requirements for technologies, incentives for further innovations are 

dampened. (3) Facilities properly equipped to test BWMS technologies are few, so increased sharing of 

data and testing protocols among such facilities is essential. (4) Discharge standards differ domestically 

and internationally, giving manufacturers multiple targets. (5) Meeting more stringent standards requires 

that BWMS consistently perform nearly perfectly; a fundamental shift in system design and operational 
6

practices would be needed to achieve this level of performance. (6) Once performance tests indicate that 

a given BWMS meets IMO D-2/ Phase 1 standards, further efforts by manufacturers to improve design 

and efficacy appear to decline.

c. What recommendations does the SAB have for addressing these impediments and constraints? 

Clearly defined and transparent programs for compliance monitoring and enforcement are needed to 

promote consistent, reliable operation of BWMS; such programs do not yet exist. Ideally, vessel crew 

would have the technological capability to self-monitor BWMS efficacy and make real-time corrections 

to maintain compliance. BWMS manufacturers should document performance metrics beyond discharge 

treatment efficacy, such as energy consumption and reliability. This would enable vessel operators to 

select systems that best integrate with their operations. Although meeting significantly higher standards 

will likely require completely new treatment approaches, the Panel can neither predict which 

combination of treatment processes will achieve the highest efficacy nor their ultimate performance. The 

Panel recommends that one or more pilot projects be commissioned to explore new approaches to ballast 

water treatment, including tests of ballast water transfer and treatment at an onshore reception facility. 

d. Are these impediments more significant for certain size classes or types of organisms (e.g., 

zooplankton versus viruses)? Can currently available treatment processes reliably achieve sterilization 

(no living organisms or viable viruses) of ballast water onboard vessels or, at a minimum, achieve zero 

or near zero discharge for certain organism size classes or types?

Shipboard impediments apply to all size classes of organisms and specified microbes. Some treatment 

systems or combinations are more effective for treating larger organisms and others for treating 

unicellular organisms. The technology exists to remove or kill the great majority and in some cases, to 

remove nearly all organisms ≥ 50 μm from discharged water. Given the volumes of water involved, 

onboard sterilization of ballast water is not possible using current technologies. It is not possible to 

verify zero (sterilization) or near-zero discharge. Such values cannot be measured in a scientifically 

defensible way.

Charge question 4: Development of reliable information 

What are the principal limitations of the available studies and reports on the status of ballast water 

treatment technologies and system performance and how can these limitations be overcome or corrected 

in future assessments of the availability of technology for treating ballast water onboard vessels?

Existing information about ballast water treatment is limited in many respects, including significant 

limitations in data quality, shortcomings in current methods for testing BWMS and reporting results, 

issues related to setting standards and for compliance monitoring, and issues related to test protocols, 

including the use of surrogate indicators. 

More broadly, however, the Panel found that because of the lack of an overall risk management systems 

approach, insufficient attention has been given to integrated sets of practices and technologies to reduce 

invasion or pathogen risk by (1) managing ballast, (2) adjustments in operation and ship design to 

reduce or eliminate the need for ballast water, (3) development of voyage-based risk assessments and 

application of Hazard Analysis and Critical Control Points (HACCP) principles, and (4) options for 

reception facilities for the treatment of ballast water. The Panel concludes that combinations of practices 
7

and technologies are potentially more effective and cost-efficient than sole reliance on shipboard 

BWMS. 

Principal limitations of available data and protocols

Data are not sufficiently compatible to compare rigorously across BWMS because standard test 

protocols have been lacking. The most recent EPA ETV Protocol, published in 2010, will improve this. 

Reporting of test failures during type approval testing is not required, although some independent test 

facilities do report failures. This should be uniform across research and other test facilities so that it is 

possible to draw conclusions about the consistency or reliability of BWMS. 

Clear definitions and direct methods to enumerate viable organisms are missing for some organisms and 

are logistically problematic for all size classes, especially nonculturable bacteria, viruses, and resting 

stages of many other taxa. Methods to enumerate viruses are not included in the proposed USCG Phase 

2 standard. The important size class of protists3 < 10 μm have not been considered adequately in 

developing guidelines and standards, although some Panel members felt that other measurements may 

indicate activity in that size class.

Alternatives to shipboard treatment of ballast water

Data on the effectiveness of practices and technologies other than shipboard BWMS are few. Use of 

reception facilities for the treatment of ballast water appears to be technically feasible (given generations 

of successful water treatment and sewage treatment technologies), and is likely to be more reliable and 

more readily adaptable than shipboard treatment. Existing regional economic studies suggest that 

treating ballast water in reception facilities would be at least as economically feasible as shipboard 

treatment. However, these studies consider that vessels only call at those regional facilities; if vessels

also call at ports outside the region without reception facilities, they would need a shipboard BWMS4. 

The effort and cost of monitoring and enforcement needed to achieve a given level of compliance is 

likely to be less for a smaller number of reception facilities compared to a larger number of BWMS. 

However, the Panel did not reach agreement on several issues related to treatment of ballast water in 

onshore reception facilities. For further details on the Panel’s views, see Section 6.4; for a review of the 

literature review on treatment of ballast water in onshore reception facilities, see Appendix B.

Recommendations to overcome present limitations

As illustrated in the ETV protocol (U.S. EPA 2010), testing of BWMS in a research and development 

mode should be distinct from testing for type approval certification and for verification. Certification 

testing should be conducted by a party independent from the manufacturer with appropriate, established 

credentials, approved by EPA/USCG. Test failures and successes during type approval testing should be 

reported and considered in certification decisions. A transparent international standard format for 

reporting, including specification of quality assurance and quality control (QA/QC) protocols and a 

means to indicate QA/QC procedures were followed during testing, are needed. In addition, the EPA 

 3 Protists refers to various one-celled organisms classified in the kingdom Protista, and which includes protozoans, eukaryotic 

algae, and slime molds. 

4 Dr. Cohen, who read these studies, objected to this sentence as being untrue and misleading and felt there had not been 

adequate opportunity for Panel discussion of the issue.
8

should develop metrics and methods appropriate for compliance monitoring and enforcement as soon as 

possible. 

Limits for selected protists < 10 μm in minimum dimension should be included in ballast water 

discharge standards and in BWMS test protocols. Suitable standard test organisms should be identified 

for bench-scale testing, and surrogate parameters should be investigated to complement or replace 

metrics that are logistically difficult or infeasible for estimating directly the concentration of living 

organisms. Representative “indicator” taxa (toxic strains of Vibrio cholerae; Escherichia coli; intestinal 

Enterococci) should continue to be used to assess BWMS. Estimates of the removal of harmful bacteria 

will be improved when reliable techniques become available to account for active nonculturable cells as 

well as culturable cells.

EPA should conduct a comprehensive analysis comparing biological effectiveness, cost, logistics, 

operations, and safety associated with both shipboard BWMS and reception facilities. If the analysis 

indicates that treatment at reception facilities is both economically and logistically feasible and is more 

effective than shipboard treatment systems, it should be used as the basis for assessing the ability of 

available technologies to remove, kill, or inactivate living organisms to meet a given discharge standard. 

In other words, use of reception facilities may enable ballast water discharges to meet a stricter standard.

A risk management systems approach should be adopted, in which combinations of practices and 

technologies should be considered as potentially more effective and potentially more cost-efficient 

approaches than reliance on one ballast water treatment technology. Hazard Analysis and Critical 

Control Points (HACCP) has been demonstrated to be an effective risk management tool in a variety of 

situations and could be applied to ballast water management.
9

2. INTRODUCTION

2.1. EPA’s Charge to the SAB 

EPA’s Office of Water provided the following background and charge questions to the SAB:

Ballast water is typically drawn in from surrounding ambient water and used to assist with vessel draft, 

buoyancy, and stability. Almost all large vessels have ballast tanks dedicated to this purpose; some 

vessels may also ballast empty cargo holds. The ballast water discharge rate and constituent 

concentrations of ballast water from vessels will vary by vessel type, ballast tank capacity, and type of 

deballasting equipment. Under current U.S. regulation and permitting requirements (discussed in 

greater detail in the White Paper), there are existing best management practices to reduce the potential 

impacts of ballast water discharges. These include ballast water exchange and salt water flushing 

(collectively referred to as BWE).

While useful in reducing the presence of potentially invasive organisms in ballast water, BWE can have 

variable effectiveness and may not always be feasible due to vessel safety concerns. In order to make 

progress beyond use of BWE, establishing a standard for the concentration of living organisms in 

ballast water that can be discharged is necessary. The United States Environmental Protection Agency 

(EPA) and the United States Coast Guard (USCG) both desire a stronger federal ballast water 

management program.

To help develop the next Clean Water Act Vessel General Permit (VGP), EPA needs an objective 

evaluation of the status and efficacy of ballast water treatment technologies and systems that are in 

existence or in the development process. A second major scientific question for regulatory agencies is to 

better understand and relate the concentration of living organisms in ballast water discharges to the 

probability of introduced organisms successfully establishing populations in U.S. waters. Given the 

complexity of the issue, EPA’s Office of Water is seeking advice from the Science Advisory Board (SAB) 

on the first issue and the National Academy of Sciences’ National Research Council (NRC) on the 

second issue. In particular, EPA is seeking advice from the SAB regarding the availability and efficacy 

of ballast water treatment systems in neutralizing (killing) living organisms that might be discharged 

from ballast tanks. For the other NRC study, EPA has requested that the NRC broadly assess and make 

recommendations about various approaches for assessing the risk of establishment of new aquatic nonindigenous species from ballast water discharges (see attachment 2 of the White Paper for the NRC 

charge).

Charge Question 1: Performance of shipboard systems with available effluent testing data5

a. For the shipboard systems with available test data, which have been evaluated with sufficient 

rigor to permit a credible assessment of performance capabilities in terms of effluent 

concentrations achieved (living organisms/unit of ballast water discharged or other metric)?

b. For those systems identified in (1a), what are the discharge standards that the available data 

credibly demonstrate can be reliably achieved (e.g., any or all of the standards shown in Table 1 

 5 EPA and the US Coast Guard have provided data they currently have to the panel. Where feasible, the panel is encouraged 

to find additional data if they have appropriate avenues to obtain those data. 
10

of the White Paper? Furthermore, do data indicate that certain systems (as tested) will not be 

able to reliably reach any or all of the discharge standards shown in that table?

c. For those systems identified in (1a), if any of the system tests detected “no living organisms” 

in any or all of their replicates, is it reasonable to assume the systems are able to reliably meet 

or closely approach a “no living organism” standard or other standards identified in Table 1 of 

the White Paper, based on their engineering design and treatment processes? 

Charge question 2: Potential performance of shipboard systems without reliable testing data

Based on engineering design and treatment processes used, and shipboard 

conditions/constraints, what types of ballast water treatment systems (which may include any or 

all the systems listed in Table 4 of the White Paper) can reasonably be expected to reliably 

achieve any of the standards shown in Table 1 of the White Paper, and if so, by what dates? 

Based on engineering design and treatment processes used, are there systems which 

conceptually would have difficulty meeting any or all of the discharge standards in Table 1 of the 

White Paper?

Charge question 3: System development

a. For those systems identified in questions 1 a and 2, are there reasonable changes or additions 

to their treatment processes which can be made to the systems to improve performance?

b. What are the principal technological constraints or other impediments to the development of 

ballast water treatment technologies for use onboard vessels to reliably meet any or all of the 

discharge standards presented in Table 1 of the White Paper? 

c. What recommendations does the SAB have for addressing these impediments/constraints? 

d. Are these impediments more significant for certain size classes or types of organisms (e.g., 

zooplankton versus viruses)? 

e. Can currently available treatment processes reliably achieve sterilization (no living organisms 

or viable viruses) of ballast water onboard vessels or, at a minimum, achieve zero or near zero 

discharge for certain organism size classes or types?

Charge question 4: Development of reliable information 

What are the principal limitations of the available studies and reports on the status of ballast 

water treatment technologies and system performance and how can these limitations be 

overcome or corrected in future assessments of the availability of technology for treating ballast 

water onboard vessels?
11

2.2. SAB’s Review Process

In response to the EPA request for an SAB assessment of shipboard ballast water management systems 

(BWMS), the SAB’s Ecological Processes and Effects Committee was augmented with additional 

experts in ballast water issues, marine engineering, and engineering treatment technologies (the Panel). 

The Panel met on July 29 – 30, 2010 to receive briefings from EPA’s OW, to hear public comments, and 

to begin discussing the charge questions. As requested, the SAB based its assessment and advice on 

information provided by OW, including the background document, Availability and Efficacy of Ballast 

Water Treatment Technology: Background and Issue Paper (June 2010), and a compilation of 

information and data on BWMS (described in Appendix A and Section 4 of this report). Teleconferences 

were held on October 26 and November 4, 2010, to discuss preliminary texts prepared by individual 

subgroups of the Panel and to hear public comments. The full Panel met again on January 25-26, 2011,

to discuss the compiled draft report and to discuss preliminary conclusions and recommendations. 

Additional teleconferences were held on March 15 and March 17, 2011, to discuss final revisions to the 

draft report. The Panel considered public comments provided throughout the advisory process. The 

Panel differed in their views regarding several issues related to onshore treatment of ballast water in 

reception facilities. The potential use of reception facilities is discussed in Section 6.4, and a review of 

the literature of onshore treatment in reception facilities is provided in Appendix B. One panel member 

did not concur with the final draft report prepared for quality review by the chartered SAB. Public 

comments were received and considered throughout the advisory process. The chartered SAB conducted 

a quality review on June 16, 2011, and approved the report with clarifying edits.

2.3. Regulatory Frameworks for Ballast Water Management 

2.3.1. U.S. Federal rules

In December 2008, the EPA issued a Vessel General Permit (VGP) for discharges incidental to the 

normal operation of commercial vessels, including ballast water, as authorized under the Clean Water 

Act (CWA). The VGP set technology-based effluent limits for ballast water that rely on “best 

management practices” and do not include a numeric discharge limit. The required VGP practices 

include flushing and exchange of ballast water by vessels in Pacific near-shore voyages and saltwater 

flushing of ballast water tanks that are empty or contain only un-pumpable residual ballast water in 

addition to mid-ocean exchange. The VGP expires on Dec. 19, 2013. 

Existing U.S. Coast Guard (USCG) rules governing ballast water, as authorized under the National 

Invasive Species Act (NISA), also rely primarily on ballast water exchange. Though the BWE 

provisions are not identical, the general principle of BWE as used by the EPA and USCG is very similar. 

NISA generally requires vessels equipped with ballast water tanks and bound for ports or places in the 

U.S. after operating beyond the U.S. Exclusive Economic Zone either to conduct a mid-ocean ballast 

water exchange (BWE), retain their ballast water onboard, or use an alternative environmentally sound 

ballast water management method approved by the USCG. In August 2009, the USCG proposed 

revising their existing rules to establish numeric concentration-based limits for organisms in ballast 

water. The proposed rule initially would require compliance with a “Phase 1 standard” that has the same 

concentration limits as the International Maritime Organization (IMO) D-2 standard (see below) and 

subsequently would require compliance with a “Phase 2 standard” that is 1000 times (1000x) more 

stringent for organisms of more than 10 μm in minimum dimension. The Phase 2 standard also contains 
12

concentration limits for bacteria and viruses. As of July 2011, the USCG has not finalized this rule, and 

in the meantime continues to require use of BWE. 

In recent years, Congress has considered but not enacted legislation that would directly set 

concentration-based ballast water discharge standards, including standards that would be 100 times 

(100x) more stringent for organisms than the USCG proposed Phase 1 standard.

2.3.2. Other Regulatory Frameworks

U.S. States

Under the CWA, U.S. states have the authority to impose their own ballast water discharge standards 

through the CWA section 401 certification process that applies to federally issued National Pollution 

Discharge Elimination System (NPDES) permits such as the VGP. A number of states have exercised 

that authority by setting numeric limits for ballast water discharges into their waters, and these numeric 

limits are included as a condition in the VGP. In addition, several states (e.g., California and some Great 

Lakes states) have enacted their own independent state laws to establish ballast water treatment 

standards. Thus, in practice, EPA’s VGP standards establish the minimum standard for ballast water 

discharges, but states retain and have exercised their authority to set standards that are more stringent. 

International Standards / Treaties

The International Convention for the Control and Management of Ships’ Ballast Water and Sediments 

(IMO Ballast Water Management Convention), adopted by the International Maritime Organization 

(IMO) in February 2004, contains concentration-based limits on organisms in ballast water set out in its 

Regulation D-2. The treaty will not come into force unless it is ratified by additional countries, and 

implementation would then require the enactment and enforcement of appropriate laws or regulations by 

the countries that are party to the treaty. However, equipment manufacturers are currently designing and 

testing equipment to meet the D-2 standards. These and the other main concentration-based limits for 

organisms in ballast water that have been proposed or adopted are shown in Table 2-1.
13

Table 2-1. The range of concentration-based limits proposed or adopted for organisms in ballast water.

“US Negotiating Position” is what the U.S. argued for in the negotiations on discharge standards for the IMO Ballast 

Water Management Convention. “California Interim” and “California Final” standards refer to the limits enacted by 

the state of California in 2006. 

A. Concentration limits for four organism classes

Organisms ≥ 50 μm

in minimum 

dimension

Organisms ≥ 10-

<50 μm in 

minimum 

dimension

Bacteria Viruses

per m3 per ml per ml per ml

IMO D-2 10 10 no limit no limit

USCG Phase 1 10 10 no limit no limit

US Negotiating Position 0.01 0.01 no limit no limit

USCG Phase 2 0.01 0.01 10 100

California Interim no detectablea 0.01 10 100

California Final zero detectableb zero detectable zero detectable zero detectable

a For California’s interim standard for organisms ≥ 50 μm , the “no detectable” standard is not associated with a 

volumetric requirement, i.e., the standard is not “no detectable living organisms” per cubic meter. 

b California’s final standard is set as “zero detectable living organisms for all size classes.” This final standard also 

does not have a volume or organism concentration associated with it.

B. Public health protective concentration limits

Toxicogenic

Vibrio cholerae

Escherichia coli Intestinal enterococci

per ml per ml per ml

IMO D-2 .01 2.5 1

USCG Phase 1 .01 2.5 1

US Negotiating Position .01 1.26 0.33

USCG Phase 2 .01 1.26 0.33

California Interim .01 1.26 0.33

California Final no detectable no detectable no detectable

2.3.3. Glossary of Terms Used

To clarify the terms used in this report, the Panel provides the following definitions.

• BWMS refers to ballast water management systems as developed by vendors for installation on 

vessels for treatment of ballast water prior to discharge. In this report, “systems” refers 

specifically to commercial treatment units, not to a systems approach to ballast water 

management.
14

• Challenge conditions refer to the challenge water (influent) conditions as specified by the IMO 

and the ETV Protocol. The IMO’s G8 guidelines for challenge conditions are specified in

paragraph 2.2.2.5 (for shipboard testing) and paragraphs 2.3.3 and 2.3.17 – 2.3.22 (for landbased testing) (at 

http://www.regulations.gov/search/Regs/home.html#documentDetail?R=09000064807e8904). 

The EPA’s Environmental Technology Verification (ETV) draft Generic Protocol for 

Verification of Ballast Water Treatment Technologies, protocol for challenge conditions are 

specified in § 5.2. (at 

http://standards.nsf.org/apps/group_public/download.php/7597/Draft%20ETV%20Ballast%20W

ater%20Prot-v4%202.pdf).

• ETV Protocol refers to the U.S. EPA Generic Protocol for the Verification of Ballast Water 

Treatment Technology, Version 5.1. 2010 (EPA/600/R-10/146), U.S. EPA Environmental 

Technology Verification Program, Washington, DC.

• G9 approval, both “Basic Approval” and “Final Approval”: Under Regulation D-3(2) of the 

IMO Ballast Water Management Convention, ballast water treatment systems that make use of 

“active substances” (biocides or other potentially harmful substances) are subject to approval by 

the IMO’s Marine Environment Protection Committee (MEPC) with respect to active substancerelated health, environmental, and safety issues. This review and approval is conducted under the 

“G9 Guidelines” developed by MEPC, available at 

http://www.regulations.gov/search/Regs/home.html#documentDetail?R=09000064807e890e. 

Basic Approval” requires laboratory or bench-scale testing, while “Final Approval” requires 

testing an actual piece of equipment. The Group of Experts on the Scientific Aspects of Marine 

Pollution (GESAMP), an advisory body established by the United Nations in 1969, conducts the 

technical reviews and makes approval or denial recommendations to MEPC. MEPC then makes 

the G9 approval decisions.

• IMO refers to the International Maritime Organization, a subsidiary body of the UN whose 

principal responsibility is to develop and maintain the international regulatory framework for 

shipping with respect to safety, environmental concerns, legal matters, technical co-operation, 

and maritime security. It accomplishes this through treaties negotiated under its auspices,

including the February 2004 International Convention for the Control and Management of Ships’ 

Ballast Water and Sediments. The Marine Environment Protection Committee (MEPC) is the 

principal IMO committee with responsibility for environmental issues associated with shipping. 

For more information: http://www.imo.org/home.asp

• IMO D-2 refers to the ballast water discharge standards (expressed as concentrations of 

organisms per unit of volume) that are contained in Regulation D-2 of the IMO Ballast Water 

Management Convention. The U.S. has not ratified the treaty, and additional countries must 

ratify it before it enters into force. Nonetheless, the D-2 standards have had an important 

influence on the design of shipboard BWMS.

• IMO D-2 / Phase 1 are ballast water discharge standards that are sometimes used in combination 

because their specifications are very similar. However, to be explicit, IMO D-2 is defined as 

shown above.
15

• USCG Phase 1 (or P-1) refers to ballast water discharge standards contained in the U.S. Coast 

Guard’s August 28, 2009, notice of proposed rulemaking. Because this is a proposed rulemaking 

that has not yet been finalized, these Phase 1 standards are not currently (as of July 1, 2011) 

legally binding. For more information, refer to 74 Federal Register 44632. The table below 

contains the text of the standards as stated in IMO D-2 and in the proposed USCG Phase 1, 

arrayed so as to enable their direct comparison (blanks in table are not omissions, but rather are 

arranged to highlight comparison of the texts).

Table 2-2. Comparing IMO D-2 with USCG Proposed Phase I Standard

IMO Regulation D-2 Standard USCG Proposed Phase 1 Standards

Discharge less than 10 viable organisms 

per cubic meter greater than or equal to 50 

micrometers in minimum dimension 

For organisms larger than 50 microns in 

minimum dimension: Discharge less than 

10 per cubic meter of ballast water;

Discharge less than 10 viable organisms 

per milliliter less than 50 micrometers in 

minimum dimension and greater than or 

equal to 10 micrometers in minimum 

dimension 

For organisms equal to or smaller than 50 

microns and larger than 10 microns: 

Discharge less than 10 per milliliter (ml) of 

ballast water; and

Discharge of the indicator microbes shall 

not exceed the specified concentrations 

described in the following paragraph: 

Indicator microbes, as a human health 

standard, shall include: 

.1 Toxicogenic Vibrio cholerae (O1

and O139) with less than 1 colony 

forming unit (cfu) per 100 milliliters 

or less than 1 cfu per 1 gram (wet 

weight) zooplankton samples ; 

.2 Escherichia coli less than 250 cfu 

per 100 milliliters; 

.3 Intestinal Enterococci less than 

100 cfu per 100 milliliters.

Indicator microorganisms must not exceed:

(i) For Toxicogenic Vibrio cholerae 

(serotypes O1 and O139): A 

concentration of <1 colony forming unit 

(cfu) per 100 ml;

(ii) For Escherichia coli: A 

concentration of <250 cfu per 100 ml; 

and

(iii) For intestinal enterococci: A 

concentration of <100 cfu per 100 ml.

• 10x D-2, 100x D-2, 1000x D-2 refer to concentration limits that are 10 times, 100 times, or 1000 

times smaller (i.e., more stringent) than the concentration limits specified in IMO D-2, for one or 

both of the organism size classes in IMO D-2 (i.e., organisms with minimum dimension ≥ 50 

μm; or ≥ 10 μm and < 50 μm). The 10x, 100x, and 1000x notations do not apply to the D-2 

indicator microorganisms. 100x D-2 has been discussed in other fora such as past Congressional 

bills and State requirements. 1000x D-2 has been discussed in other fora such as the potential 

Phase II standards in the USCG August 2009 proposed rule or as described in state requirements

• Type approval refers to the process under which a type of equipment is tested and certified by a 

Flag state or its authorized representative (such as a Class society) as meeting an applicable 

standard specified in treaty, law or regulation. This testing is conducted on a sample piece of 

equipment which in all material respects is identical to the follow-on production units. For the 
16

IMO Ballast Water Management Convention, type approval testing (sometimes called “efficacy 

testing”) is conducted under the G8 Guidelines described in Regulation D-3(1) of the 

Convention. The guidelines require both land-based and shipboard testing to verify the 

equipment’s ability to meet the IMO D-2 standards. In the U.S., a generally similar type approval 

procedure was proposed as part of the USCG’s August 28, 2009, notice of proposed rulemaking. 

• Verification Organization (VO) refers to the party responsible for overseeing the test facility’s 

test Total Quality Assurance Plan (TQAP) development, overseeing testing activities, and 

overseeing the development and approval of the Verification Report and Verification Statement 

for the ballast water treatment system. Within the ETV Program, verification organizations are 

the managers and operators of the various technology centers under cooperative agreements with 

the EPA (U.S. EPA 2010).

2.4. Applying Risk Assessment Principles to Ballast Water Management

The charge to the Panel focused primarily on whether BWMS could meet specific discharge standards, 

now or in the future. However, in its assessment the Panel found that combinations of practices and 

technologies should be considered as potentially more effective than reliance on BWMS technology (see 

section 6.5). Therefore this section sets the stage by exploring the use of risk assessment as a way to put 

strategies for treatment of ballast water into a probabilistic decision-making process. This process should 

be applied to the entire system of ballast water management and not to just one technique, device or 

practice. Each step of the process, from taking on ballast water at the port of origin to its discharge into 

the receiving port, depends upon the others. Risk assessment is a means of treating the entire ballast 

water management process in a holistic fashion and changes to each step can be evaluated within a 

defined risk-based process. A holistic approach to ballast water management includes the regulatory 

environment, the training of personnel, quality control, and environmental sampling. Risk assessment 

also provides the framework for risk management. One such framework is the Hazard Analysis and 

Critical Control Points (HACCP). The HACCP process and its application to ballast water management 

are described in section 6.6.

2.4.1. Risk Assessment of Nonindigenous Species

The establishment of a nonindigenous species is the joint probability of how often species are

introduced, the initial population size necessary to ensure reproduction, and the probability that 

organisms would find a suitable environment for propagation. This joint probability is low for any one 

species or specific shipping event. However, a large number of species can be transported via ship, and 

thousands of ships arrive at U.S. ports, creating a substantial probability that a nonindigenous species or 

a new pathogen will become established. Given that shipping is a major industrial activity that will 

continue far into the future, even a small probability for each ship and for each species will result in 

successful invasions. The goal of a ballast water management (BWM) program is to lower that 

probability, especially for particularly damaging species and pathogens. For a BWM program to be 

successful, the goals need to be specific and measurable, and the operational context needs to be 

understood. First, a model of the relationship between the number of organisms in ballast water and the 

likelihood of invasion or infection by a pathogen needs to be derived.
17

Probabilistic Approach to Deriving Risk Due to Nonindigenous Species

A foundation for the risk assessment for invasive species has been established (Drake 2004, 2005;

Landis 2004). The process is density-dependent, with an increase in the density of organisms leading to 

an increase in population growth rate (Drake 2004). Modeling also has demonstrated the importance of a 

beachhead effect, where a population increases in a relatively isolated habitat patch before spreading to 

the remainder of the environment (Deines et al. 2005). Both Drake (2005) and Deines et al. (2005) 

recognize the importance of eliminating the organisms during the initial invasion event or destroying the 

beachhead in order to implement control.

Deines et al. (2005) used spatially explicit stochastic difference models and Drake and Lodge (2006) 

employed stochastic differential equations to model invasion events. In both studies the importance of 

understanding the stochastic aspects of colonization, the initial population size (propagule pressure) and 

density dependent effects on population growth were important in determining the probability of 

invasion. The actual dynamics of invasions were sensitive to initial conditions. The combination of 

stochastic and non-linear components results in a distribution of outcomes in both studies. This means 

that any relationship between propagule pressure and probability of invasion will be a distribution of 

outcomes. These foundations have been used to estimate risk in case studies (Drake et al. 2006; Colnar 

and Landis 2007). A risk assessment for managing ballast water invasion should have as its foundation 

the stochastic-non-linear nature of the invasion process.

Propagule Pressure and Invasion Relationships

It is possible to derive relationships between the number of organisms with an invasive potential 

(propagules) and the probability of an invasion over a specified amount of time. Such a relationship is 

described by the upper panel of Figure 2-1. It is assumed that the greater the number of propagules, the 

greater the probability that an invasive potential will be established. In this instance, it is assumed that 

the relationship is sigmoidal and has a threshold, but a number of curves are possible and the actual 

curve may be specific to the type of organism or environment. The solid line represents the central 

tendency of the relationship, with the dashed lines representing confidence intervals. Note that the 

confidence intervals include the possibility of a successful invasion even without propagule pressure 

from ballast water and also the likelihood of no invasion even with organisms escaping. After all, 

organisms can come from a variety of sources other than ballast water.

The lower panel of Figure 2-1 illustrates a process for setting targets for the number of organisms in 

ballast water. First a policy decision is made about an acceptable frequency of successful invasion over a 

specified amount of time. Existing information may be inadequate, so derivation of this frequency may 

require an assessment tailored to a specific habitat, species, endpoint, and location. Reading across the 

graph to where this rate intersects with the concentration-response curve gives the numbers of organisms 

corresponding to the low, expected and high values. Trade-offs can then be made on the likelihood of 

success in meeting the specified target and the costs of achieving the goal.

Although these graphs were drawn to express the relationship with one species of concern, similar plots 

may be derived for discharges with a large number of species. The greater the diversity of species and 

life stages, the greater the probability of an invasion by at least a single species.
18

Figure 2-1. This conceptual diagram illustrates the relationship between propagule pressure (concentration) and the 

probability of an invasion by that species over time. The confidence intervals around the expected probability describe the 

uncertainty in the relationship (A). Such a curve will allow a quantitative determination of suitable goals for reducing 

potential invasions from nonindigenous species. Once a level of probability is agreed upon, the corresponding values of 

propagule pressures likely to produce the result can be obtained (B). 

Propagule Pressure (number of organisms)

Probability of invasion/Time

0

100

50

Expected value

Confidence limit

Acceptable rate of invasion

Range of 

propagule 

pressure

Propagule Pressure (number of organisms)

Probability of invasion/Time

0

100

50

Expected value

Confidence limit

A

B
19

2.4.2. Ballast Water Management Goals and the Decision Making, Risk Assessment Context

In order to evaluate the various types of BWMS, it is important to understand how they fit into a 

decision-making context. This means the management goal has to be clearly defined as in the graphical 

model (Figure 2-1). In addition, the effectiveness of ballast water treatment has to be evaluated within 

the context of a ship carrying cargo, human food and waste, and many organisms attached to the hull. 

The sea chest (a portion of the ship where seawater can be loaded or discharged) also can be a source of 

nonindigenous species. There is also the possibility of human error in the treatment process that may 

lead to the escape of organisms or the release of toxic materials. Each of these items will be covered in 

the paragraphs below.

The Goal: What Does “Zero” Mean?

What does “zero” discharge of nonindigenous species and other organisms mean as a goal, since such a 

value is essentially not measureable directly (see section 3)? The required sample volumes are 

enormous, there are refugia from treatment within the ballast water tanks, and the discharge is into an 

environment with multiple sources of invasive species. Operational definitions are very important and 

may prove more useful in making a decision about ballast water treatment options. For example, does 

“zero” mean that a discharge from a specific ship will contain no organisms that will colonize or infect a 

port environment for that one particular combination of disinfection treatment and vessel discharge?

This is a very specific criterion but it is not necessarily protective. Furthermore, given the logistics 

needed to sample and enumerate organisms in a discharge, it will not be possible to meet this 

requirement for every discharge of every ship. 

On the other hand, “zero” could mean the treatment technology or system will prevent introduction of a 

harmful invasive organism or disease to that port over a 10-year period. This is a very different criterion, 

a performance-based requirement that states the goal (no invasion or infection) over a specified time 

frame. Individual treatments on certain ships may fail, but an overall system would ensure that any 

colonizing organisms were quickly eradicated or that other methods would be employed to prevent their 

propagation. These two “zero” goals are very different and each puts onboard or land-based treatment 

options into specific and differing contexts. In order to rank the various technologies and treatment 

systems, therefore, the specific goals of the program need to be carefully defined.

There is also the question of specific goals for the protection of the port from nonindigenous species and 

pathogens. Are there specific requirements for each category of organism or is a combination approach 

to be attempted? Consider pathogenic organisms as an example. In ballast water, a large proportion of 

the organisms likely are not pathogenic, but the human welfare implications may be higher for the 

pathogenic organisms than non-pathogenic organisms. Is the goal protection against human pathogens or 

those pathogens that may infect shellfish and fish populations, destroy important sea grass beds, or other 

segments of the ecological structure of the receiving port? Depending upon the specific policy goals, 

different propagule pressure-infection relationships may need to be considered.

Context of a Cargo or Tanker Ship and the Port Facility

As the specifications for the treatment process are made explicit, it is also important to understand the 

context of a ship and its port facility. Ballast water would be only one of the potential sources of 

nonindigenous species and pathogens brought by a vessel. Ships contain cargos of varied types, crew, 
20

food, human waste, and hull fouling organisms, each of which also could be sources of invasive species. 

The port facility may also contain a variety of other vessels that may be sources of nonindigenous 

species and pathogens. Understanding the efficacy of the treatment program needs to be placed into this 

broader context.

Cargo may contain insects, fungi, seeds and spores that can be released to the environment as the cargo 

is unloaded or transported. Food can be another source of nonindigenous species, especially if living 

organisms are transported. Human waste can be a source of pathogens, but can be disposed of using 

appropriate facilities. Fouling of the hull of a ship can be a source of nonindigenous species or 

pathogens depending upon the origin of the ship, route and time of transit, and the effectiveness of the 

anti-fouling paint and the overall condition of the hull. The sea chest is a repository of organisms from 

across the travels of the vessel.

A confounding factor is that a number of other vessels will use the same port facilities, and all are 

potential sources of invasion. Fishing fleets and pleasure craft, for example, often take very long 

voyages and may transport nonindigenous species to a harbor. Also, these “other” vessels exist in 

regulatory environments different than those of cargo ships, barges, and tankers, regulations that may be 

less restrictive with respect to the transport of nonindigenous species. Although not directly affecting the 

infection potential of any single ship, these “other” vessels can confound determination of treatment 

effectiveness or identification of an invasive species’ source. So although there may be zero propagules 

in ballast water discharged at a facility, there will remain some probability of an invasion at the port. 

Hence there is a non-zero confidence interval in the example considered in Figure 2-1. 

The risks due to invasion are not the only risks to be considered in BWM. It will be important to assess 

the potential impacts of decontamination and the effluent upon the environment. Does disinfection for 

pathogens increase the risk to the environment from the treatment? The number of ships that use a port 

may also contribute to the trade-off. Decontamination activities that release an effluent with some 

residual toxicity may not pose an important risk to a facility that has a low volume, but may be 

important in a busier port. Some ports are very specialized. Port Valdez, Alaska specializes in the 

shipping of crude oil and some oil product. Cherry Point, Wash. is a port that currently receives crude 

from a limited number of sites to the refineries and bauxite for the smelter. Other facilities, such as New 

Orleans or Seattle-Tacoma, receive a variety of container ships and cargoes from across the world. 

Shipboard emergencies, accidents, human error, and equipment failure should be considered in the risk 

analysis and decision-making process. At times, weather conditions or shipboard emergencies may 

preclude the operation of shipboard treatment facilities. Operator error or equipment failure may happen 

on shipboard or on-shore facilities just as it does in waste-treatment facilities. However, in wastewater 

treatment facilities, strong programs of operator training and certification are established, unlike for 

shipboard BWMS. In parts of the U.S., hurricanes and northeasters can damage ships and on-shore 

equipment. No matter the weather, accidents and equipment failure will occur and will introduce 

nonindigenous species to a port facility. Maximizing reliability of the BWMS should be an important 

part of the risk analysis process.

BWM in an Overall Management Program

Large-scale establishment of species have occurred from what appear to be multiple invasions. Kolar 

and Lodge (2001, 2002) and Kolar (2004) describe examples for the Great Lakes in which populations 
21

of European fish have been established from multiple invasion events. European green crab was 

established in San Francisco in the late 1980s and the species has spread north along the west coast 

(Behrens and Hunt 2000). Invasions take time, often decades, are often due to multiple releases, and are 

difficult to control once established. A BWM strategy to decrease the rate of successful invasions should 

be part of an overall plan for the reduction of invasion events, monitoring, containment and eradication. 

Emphasis only on one aspect, the initial invasion event, is not likely to reduce the risk of successful 

invasions to an acceptable probability. The Hazard Analysis and Critical Control Points (HACCP)

approach incorporates the context of the risk, potential points of control, and is very flexible in 

application. HACCP and its use for the management of invasive species are discussed in Section 6.6.

Summary

In summary, decisions about approaches to ballast water management can be viewed within a risk 

assessment framework. This framework should incorporate the following features:

• Recognition of the stochastic and non-linear nature of the invasion process;

• Clear definition of management goal needs; and

• Evaluation of the effectiveness of BWMS within the context of other sources of invasive 

species on the vessel, the treatment system, and the specific receiving habitat.

A ballast water management strategy to decrease the rate of successful invasions should be part of an 

overall plan to reduce invasion events, and their subsequent monitoring, containment, and eradication

activities. Emphasis only on one aspect, the initial invasion event, is not likely to reduce the risk of 

invasions to an acceptable probability. Such management systems are addressed in Sections 6.5 and 6.6

of this report.
22

3. STATISTICS AND INTERPRETATION 

3.1. Introduction 

A consideration of statistical issues encountered in testing performance of BWMS is essential to the 

credible evaluation of the performance data – whether that evaluation is done by expert panels, testing 

facilities, or regulators. This section presents key statistical considerations relevant to conditions under

which BWMS performance is evaluated. A more detailed discussion of these issues is provided in 

Appendix C. Testing conditions include the need to sample large volumes of water, particularly for the 

size class of organisms ≥ 50 μm in minimum dimension (nominally zooplankton, referred to hereafter as 

‘zooplankton-sized organisms’) and to apply statistical methods that can quantitatively assess the 

confidence of test results obtained from counts of low numbers of organisms. These discussions pertain 

to both land-based and shipboard verification testing to determine conformity to a given performance 

standard in a type approval process; the same statistical theory applies to compliance testing by port 

state control officers for compliance or gross non-compliance (e.g., exceedance of a standard by orders 

of magnitude). 

Credible testing requires the following process: Water must be collected and filtered to concentrate 

organisms into a manageable volume. The volume of ballast water carried by commercial ships ranges 

from a few thousand m3 to more than a hundred thousand m3

. The volume that must be sampled 

following treatment is a small fraction relative to that total volume but, nonetheless, a large volume must 

be filtered to determine the number of live zooplankton-sized organisms. This size class has the lowest 

concentration threshold – that is, organisms per m

3 vs. organisms per ml in the other two size classes –

and represents the most challenging size class in terms of sampling to achieve statistical rigor. Hence, 

many of the examples in the following discussion will focus on zooplankton-sized organisms. The 

required sample volumes for these organisms are in the range of five to tens of m3; the latter 

approximates the volume of a city bus. In all size classes, subsamples of the concentrated volume are 

analyzed for viable (living) organisms, because all standards are based on the number of organisms 

surviving the treatment method. Once these counts are in hand, how reliably they portray conditions in 

the ballast water discharge must be determined. To accomplish this task, the live organism counts are 

analyzed using statistical methods to assess the uncertainty associated with the counts. 

Assessing uncertainty in test results requires accounting for the spatial distribution of zooplankton-sized 

organisms in the sampled volume of water. Different probability distributions apply depending upon 

whether organisms are randomly distributed throughout a sample or are aggregated. Therefore, this 

section illustrates how the use of appropriate probability distributions can characterize the level of 

reliability in taking the important inferential step from observing actual organism counts to determining 

whether a stated standard has been met.

3.2. Assessing Whether Ballast Water Standards Can Be Met — The Statistics of Sampling 

Without a well-defined, rigorous protocol based upon probability sampling, any standard will be 

difficult to assess and defend, and it will be impossible to compare the effectiveness of different BWMS. 

To outline what a sampling scheme might entail, and what sorts of information it would yield, it is 

necessary to investigate the probabilistic characteristics of plankton in ballast water. 
23

Organisms can have one of two spatial characteristics: they can be randomly dispersed or clumped 

(aggregated) (see Lee et al. 2010). Because any sampling protocol is a function of the organisms’ spatial 

distribution, it is critical to understand the distribution in the tank and discharge pipe and then sample 

accordingly. For randomly distributed organisms that are not abundant, the Poisson distribution can be 

used to estimate probabilities and conduct statistical power analyses (the probability that the sampling 

will find a vessel in or out of compliance when that is the case). Other hypervariable discrete alternatives 

to the Poisson distribution are available, such as the Poisson Log Normal and Poisson Inverse Gaussian 

distributions. The Panel chose to focus on the Poisson distribution because statisticians examining 

samples of treated ballast water have used the Poisson distribution, and the theoretical determination and 

empirical data collected thus far support its use. The Panel notes, however, that the negative binomial 

distribution is appropriate as the underlying statistical model for concentrations of organisms that are 

spatially aggregated. 

3.2.1. The Poisson Distribution

Theoretical Considerations

The Poisson distribution has the property that its variance is equal to its mean, resulting in an increase in 

variability at higher densities. One way to assess whether the Poisson distribution is appropriate is to 

calculate the variance-to-mean ratio and compare it to 1.0. If a Poisson distribution is used, a single 

representative sample must be collected. To meet this requirement, the EPA Environmental Technology 

Verification (ETV) Generic Protocol for the Verification of Ballast Water Treatment Technology (U.S. 

EPA 2010) specifies that the sample be collected continuously over the entire discharge of the ballast 

tank and in an isokinetic manner. Assuming a given concentration, one can calculate the sample volume 

needed to guarantee a stated probability of finding at least a single planktonic organism (plankter) in that 

volume. An underlying assumption is that organisms are randomly distributed. Spatially aggregated 

populations present additional difficulties (see below), but if all organisms are counted in a continuously 

and isokinetically drawn representative sample, the issue of spatial distribution can be minimized or 

eliminated. 

A major challenge of sampling at low organism concentrations is that many samples will have

zero live organisms because the few live organisms present are missed. To improve the 

probability of detecting them, impractically large volumes must be sampled and excellent 

techniques must be used to enable detection (Figure 3-1). For example, when the water to be 

evaluated has a known concentration of one organism in 1 m3

, the probability of a 1 m3 sample 

containing zero organisms is 36.8%; if the known concentration is 0.01 organism in 1 m3

(equivalent to one organism in 100 m3), the probability of obtaining a sample with zero 

organisms is ~99% (Lee et al. 2010; Appendix C). Furthermore, “If a small volume is used to 

evaluate whether the discharge meets a standard, the sample may contain zero detectable 

organisms, but the true concentration of organisms may be quite high.... The general point is 

that more organisms may be released in ballast discharge using a stringent standard paired with 

a poor sampling protocol than a more lenient standard paired with a stringent sampling 

protocol” (Lee et al. 2010, p.72, emphasis added).
24

The ETV Protocol stipulates that biological samples (for all three size classes) should be continuously 

acquired on a time-averaged basis from a sampling port positioned in fully turbulent flow (U.S. EPA 

2010), and are thus representative of the entire volume to be sampled. Organism abundance in BWMS 

testing can be statistically represented by the Poisson distribution and, therefore, the cumulative or total 

Figure 3-1. Illustration of the need to sample very large volumes to detect low concentrations of organisms 

present, assuming random distribution: Probability distributions for random samples of 1 m2 for a randomly 

distributed population with 10 (A), 1 (B), or 0.01 (C) organisms m-2

. Red squares represent random samples. The 

data are displayed in terms of area with units of m2

, but the probabilities are the same for volumes. Plots on the 

right indicate the probability that a 1 m2 sample will contain a given number of organisms. At low 

concentrations, the concentration of organisms likely will be estimated as 0 organisms m-2

, unless very large 

volumes are sampled. (Source: Lee et al. 2010).
25

count is the key test statistic (Lemieux et al. 2008; Miller et al. 2011). A Chi-square distribution can also 

be used to approximate confidence intervals (CIs). However, experimental validation must be obtained 

to ensure that testing organizations can accomplish detection of live organisms with quantified 

uncertainty (see section 6.2.4 on viability).

The available methodologies for testing compliance with the IMO standards for zooplankton-sized 

organisms are at or near the analytic detection limits. For example, based on the Poisson distribution for 

a 95% CI from the Chi-square distribution, 30 m3 (30,000 L) must be sampled in order to find and count 

< 10 organisms m-3 with the desired level of precision (U.S. EPA 2010; Appendix C).

The ETV Protocol provides examples of the sample size needed to provide the level of precision needed 

to achieve a 95% upper confidence limit that is no more than twice the observed mean and does not 

exceed the targeted concentration (Tables 3-1 and C-1, Appendix C; U.S. EPA 2010). If the volume of 

subsample that is analyzed is increased, then validation experiments should be conducted to ensure that 

counting accuracy is acceptably high. The Poisson distribution assumption still applies to organisms in 

the next smaller class (here, referred to as “protist-sized” organisms, or organisms ≥10 μm and < 50 μm

in minimum dimension), and the ETV Protocol provides examples with a more stringent level of 

precision than is used for the larger size class (Table C-1, Appendix C; U.S. EPA 2010). At present, 

confirmation of the Phase 1 standard (< 10 protist-sized organisms mL-1) represents the practical limit 

that can currently be achieved by testing facilities in the U.S. (e.g., MERC 2009a, 2010a, 2010b; Great 

Ships Initiative 2010). In addition, determining viability of protist-sized organisms remains problematic 

because many organisms do not move during time scales over which they are observed (as do many 

zooplankton; see section 6.2.4 for a discussion of viability determination).

Table 3-1. Sample volume of treated ballast water required relative to treatment standards for organisms ≥50 μm 

(nominally zooplankton), assuming that the desired level of precision of the estimated density is set at the 95% 

confidence interval of the Poisson distribution (= twice the observed mean and not greater than the standard limit). 

These are the required whole-water sample volumes that must be concentrated to 1 L as a function of N, the number 

of 20 1-mL subsamples analyzed. (Source: U.S. EPA 2010).

N= 1 3 5

Concentration (i.e., performance 

standard) (individuals m-3)

Sample Volume Required 

(m3)

0.01 60,000 20,000 12,000

0.1 6,000 2,000 1,200

1 600 200 120

10 60 20 12

It is expected that the statistics governing the smallest size classes—the < 10 μm protists proposed 

below, and the indicator and pathogenic bacteria (Escherichia coli, Enterococci spp., and Vibrio 

cholerae)—will be similar to the two size classes discussed here. That is, treated samples will be wellmixed and will have sparse populations collected from representative samples of ballast water; thus, the 

Poisson distribution would be applicable. 

Laboratory experiments

Laboratory experiments with protist cultures support use of the Poisson distribution (Nelson et al. 2009;

Steinberg et al., accepted with revisions; Appendix C). Based on results of laboratory experiments with 
26

two sizes of standardized microbeads at different densities as imperfect proxies of protist- and 

zooplankton-sized particles, Lemieux et al. (2008) recommend that samples for analysis of protist-sized 

organisms be concentrated by at least a factor of five, and that at least four replicate counting chambers 

should be analyzed for acceptable accuracy and precision (see Appendix C for details). Furthermore, 

Lemieux et al. (2008) determined that the zooplankton size class requires a sample size of greater than 6 

m3 concentrated to 0.5 L and analysis of at least 450 1-mL aliquots. Because these higher concentration 

factors are likely unrealistic, Lemieux et al. (2008) suggest that larger sample sizes and improved 

analytical methods be used.

When concentrations are close to the performance standard, a single sample may require too large a 

volume of water to be logistically feasible. In that case, complete, continuous time-integrated sampling 

(with the entire volume analyzed) and combining samples across multiple trials can improve resolution 

while maintaining statistical validity. To that end, Miller et al. (2011) applied statistical modeling (based 

on the Poisson distribution) to a range of sample volumes and plankton concentrations (see Appendix C 

for details). They calculated the statistical power of various sample volume and zooplankton 

concentration combinations to differentiate various zooplankton concentrations from the proposed 

standard of < 10 live organisms m-3

. They concluded that three trials of time-integrated sampling of 7 m3

from a ship’s ballast water discharge theoretically can result in 80% or higher probability of detecting 

noncompliant discharge concentrations of 12 vs. 10 live organisms m-3. Thus, pooling volumes from 

separate trials will allow lower concentrations to be differentiated from the performance standard, 

although the practicability and economic costs of doing so have not been evaluated. 

It is important to note, however, the practical limits of increasing statistical sample sizes that may 

already tax the capabilities of well-engineered land-based ballast water test facilities used in verification 

testing. Shipboard testing in the U.S. has been done on a pilot scale to date (i.e., the USCG Shipboard 

Testing Evaluation Program, STEP), but pooling volumes from multiple trials might also be problematic 

on vessels used for shipboard verification testing and compliance testing. According to Table 3-1, to 

meet a standard 10 times more stringent than D-2/ Phase 1 would require anywhere from 120-600 m3 of 

whole-water sample volumes, which is impracticable; test facilities in the U.S. typically analyze ~5 m3

of water per test (e.g., MERC 2009a, 2010a, 2010b; Great Ships Initiative 2010).

Additional challenges of sampling large volumes 

As outlined in Lee et al. (2010), the detection of viable organisms at very low concentrations is a major 

practical and statistical challenge, partly because of the inherent stochasticity of sampling. Due to 

random chance, the number of organisms in multiple samples taken from the same population will vary. 

In addition, very large volumes of water must be sampled in order to accurately estimate the organism 

densities. Three other considerations merit attention.

First, statistical approaches rest upon the premise that the samples realistically represent the actual 

concentrations of organisms discharged. This premise is based upon two assumptions: all organisms are 

detected in the analyzed volume (no human or equipment errors), and organisms are randomly

distributed in both ballast tanks and discharge water. Neither assumption will be true all of the time. 

Human and equipment errors will occur, and organisms are typically “patchy” or non-random within the 

water column of a tank or the stream of a large-volume discharge (Murphy et al. 2002; U.S. EPA 2010). 

If appropriate quality control and assurance procedures were used in collecting the data, then ideally

human error and equipment malfunction would have been accounted for. The degree of randomness can 
27

be determined by calculating the variance-to-mean ratio from multiple samples and comparing the 

resulting ratios to 1.0. Additionally, analysis of a time-averaged sample taken continuously in an 

isokinetic manner renders this assumption moot.

Second, the logistics of managing large sampling containers, sample transport costs (since samples 

usually are not processed aboard ship), analytical supplies, and personnel time would make it 

impractical to process all of the volume of, for example, even one 100 m3 sample, much less multiple 

samples, especially in type approval of BWMS when multiple successful tests are required. Lee et al. 

(2010) calculated the probability of finding one or more organisms in a sample for a series of organism 

concentrations and sample volumes (Table C-2, Appendix C). These calculations show that 100 L of 

ballast must be sampled to have a > 99% probability of detecting at least 1 zooplankton-sized organism 

when the true concentration is 100 organisms per m3. When small sample volumes are collected, the 

probability of detecting an organism is low even at relatively high organism concentrations; for 

example, organisms will be detected in fewer than 10 percent of subsamples if a 1-L sample is taken and 

the “true” concentration is 100 organisms m-3. Lee et al. (2010) then estimated the upper possible 

concentration (UPC, upper 95% CI) of organisms actually present in ballast water from the number of 

organisms in a sample volume based on the Poisson distribution. Zero organisms detected in a 1-m3

sample could correspond to a true concentration of organisms in the ballast tank of up to ~3.7 organisms 

m-3; if the sample volume is only 1 L, zero organisms detected could correspond to a true concentration 

of ~3,700 organisms m-3 (Table C-3, Appendix C).

Third, in the above analyses, the true concentrations are known. The goal in sampling unknown 

concentrations is to accurately assess whether a given BWMS treats water with true organism 

concentrations that meet a given performance standard. Inherent stochasticity of sampling may result in 

an indeterminate category, as well, and the probability of obtaining an indeterminate evaluation 

increases with decreasing sample volume and increasing stringency of the ballast water standard (Figure 

C-1, Appendix C). For example, it would be necessary to sample ~0.4 m3 of ballast water to determine 

whether the D-2/Phase 1 standard of < 10 zooplankton-sized organisms m-3 was met if fewer than 

approximately 10 organisms were observed in the sample (Figure C-1B, Appendix C).

3.2.2. Spatially Aggregated Populations – Negative Binomial Distributions

This section illustrates how difficult statistical analyses can become when working with spatially 

aggregated populations and emphasizes the gains made from doing a complete count of a representative 

sample that has been continuously and isokinetically taken. 

If organisms are aggregated rather than randomly distributed in a ballast tank, a different statistical 

approach is required. For aggregated populations, the variance exceeds the mean (negative binomial 

distribution, σ2 > μ); thus, as the variance increases, the number of organisms in a random sample is 

increasingly unpredictable. Lee et al. (2010) recommend use of the negative binomial distribution to 

model aggregated populations. 

Because it is more difficult to accurately estimate the true concentration, more intensive sampling is 

required. For a randomly distributed population with a true concentration of 1 organism m-3, ~37% of 

the subsamples from a 1 m3 sample of treated ballast water would contain zero organisms; for an 

aggregated population with a dispersion parameter of 0.1, ~79% of the subsamples would contain zero 

organisms (Figure C-2, Appendix C; Lee et al. 2010). As aggregation increases, the probability of 
28

samples containing either zero organisms or large numbers of organisms relative to the true 

concentration also increases (Figure C-3, Appendix C). Thus, large numbers of subsamples from large 

sample volumes must be taken to account for aggregated populations; otherwise, there will be a high 

probability that the concentration estimates from sample analyses will be either much lower or much 

higher than the true concentration.

Determination of whether a population is aggregated is complicated, since it is the scale of the 

aggregation pattern relative to the size of the sampling unit that controls the estimate of aggregation 

(Figure C-3, Appendix C). Lee et al. (2010) recommend the Taylor power law (Taylor 1961) as an 

alternative to the negative binomial, because it can accommodate a wider range of aggregated 

distributions than the negative binomial. 

Overall, the degree of aggregation represents challenges in sampling sufficiently large volumes of 

ballast water to determine whether a given BWMS passes or fails to meet standards more stringent than 

the present IMO guidelines, even if the true concentrations of organisms are 10 to 1000 times higher

than the performance standard. This remains a problem in quantifying many protist-sized organisms, but 

becomes less of a problem with very small organisms such as bacteria, which have a tendency to clump 

but are effectively counted as colonies and not individuals. However, laboratory experiments provide 

data supporting use of the Poisson distribution to analyze ballast water samples (Lemieux et al. 2008; 

Nelson et al. 2009; see Appendix C). 

3.3. Interactive Effects

A final consideration regarding statistical analysis is the potential for covariance, or interactive effects 

among environmental conditions – for example, a treatment system may perform well under hightemperature or high-biomass conditions, but not both (Ruiz et al. 2006). To address this problem, 

covariate measurements should be carefully addressed in experiments, and treatment evaluations should 

consider the potential for interactions and target tests of especially challenging combinations. 

3.4. Certainty of Results

As with all statements that are based upon statistical sampling, there is always a stated non-zero error 

probability associated with a particular statistical conclusion. Thus, without a complete census of a 

ship’s entire volume of ballast water, one can never claim to be 100 percent certain that the 

concentration of live zooplankton-sized organisms is below a discharge standard. Available 

methodologies to test D-2/ Phase 1 compliance are presently at or near analytic detection limits for the 

two largest organism size classes. The D-2/ Phase 1 performance standards are measurable at present 

based on land-based and shipboard testing approaches, however, new or improved methodologies will 

be required to increase detection limits. 

From the examples above, statistical theory shows it is theoretically possible to detect adherence to a 

very low discharge standard (e.g., 1000x more stringent than D-2/ Phase 1). Measuring to a 1000x more 

stringent standard, however, is impracticable at the present time because of the logistics of collecting, 

reducing, and counting organisms in all size classes within the volumes of water required. Detecting 

achievement of a standard ten times more stringent may be possible (although consensus has not been 

reached on this), but it seems unlikely for the reasons mentioned above that detecting achievement of a 

100x more stringent standard is possible.
29

3.5. Conclusions

• Rigorous statistical sampling protocols (that may include consideration of the spatial 

distribution of plankton in ballast water) and subsequent statistical analysis are required to 

assess whether a BWMS meets desired performance standards.

• Detecting organisms in low abundance is a difficult problem that requires sampling of very 

large volumes of water, especially for the zooplankton-sized organisms (≥ 50 μm).

• The initial sample volumes needed are a function of the degree to which the sample volumes 

are concentrated, the performance standard, and the desired level of confidence (e.g., 95%, 

which is used most often in ecological investigations).

• The Poisson distribution is recommended as the model for statistical analysis of treated water 

samples.

• Available methodologies to test D-2/ Phase 1 compliance are presently at or near analytic 

detection limits for the two largest organism size classes. New or improved methodologies 

will be needed to increase detection limits.

• The D-2/ Phase 1 performance standards are measureable at present. Because of the logistics 

of collecting, reducing, and counting organisms in all size classes within the volumes of 

water required to achieve a standard 1000 times more stringent than the D-2/ Phase 1

performance standard, measuring adherence to a 1000x more stringent standard may be 

impracticable. Measuring adherence to a standard that is 10x more stringent may be possible

if a continuously isokinetically taken representative sample is used. It seems unlikely, for 

reasons mentioned above, that a 100x more stringent standard could be measured at present.

• Statistical conclusions at a stated confidence level always have an associated error 

probability; thus, “100 percent certainty” is not statistically possible without a complete 

census of a ship’s entire ballast water contents.
30

4. PERFORMANCE OF SHIPBOARD SYSTEMS WITH AVAILABLE 

EFFLUENT TESTING DATA 

4.1. EPA’s Charge Questions

This section responds to Charge Questions 1 and 2, which ask the Panel to assess the documented 

performance of existing BWMS in terms of quality of discharged ballast water, and to assess the likely 

future performance of BWMS based on their design and treatment processes. 

4.2. Assessment Process

A subgroup of the Panel led the assessment of BWMS technologies. The subgroup considered only the 

information compiled by EPA through solicitation of various Maritime Administrations that have 

granted Type Approval certifications, direct communication with developers and manufacturers of 

BWMS, and searches for publically available sources (such as journal or conference publications and 

third-party reports available through the Internet). This information (listed in Appendix A) included data 

packages, reports, publications, certification documents, and other available information on the 

performance of BWMS.

Three subgroup members independently examined in detail all data packages, with two other members 

providing review oversight and quality control. The type, amount, and quality of material in the data 

packages varied—some contained only a type approval certificate, while others included land-based and 

shipboard testing methods and data, documentation of G9 approval, a type approval certificate, and 

press releases describing the sale of systems for use on commercial vessels. The Panel notes that BWMS 

are still evolving with an ever-growing number of manufacturers developing systems. Thus, this analysis 

represents a snapshot in time. No new data or information was considered beyond packages submitted to 

the SAB by December 1, 2010.

4.3. Assessing the Reliability of Existing Data

The three primary reviewers independently scored each package as having “reliable” or “unreliable”

data. To earn a “reliable” rating, the data package had to include, at a minimum, methods and results 

from land-based or shipboard testing. A BWMS holding a certificate of type approval without 

supporting testing data was scored as having “unreliable” data because it was impossible to determine 

the validity of the testing procedures and, therefore, the validity of the data. If a BWMS’s data package 

included one or more test reports, the data package was examined according to the following criteria: 

• The operational type of system (e.g., deoxygenation + cavitation) was determined to be 

generally appropriate for shipboard use (e.g., can it meet required flow capacities, size, and 

power requirements).

• The technical literature supported the fundamental use of the technologies used (e.g., is it 

well documented that using the approach will safely and effectively remove, kill, or 

inactivate aquatic organisms).

• Laboratory testing was conducted with “reasonable and appropriate methods” (i.e., methods 

commonly used in aquatic studies or alternative methods that appear rigorous and equivalent 

to a standard, common approach). 
31

• Land-based testing was conducted with reasonable and appropriate methods; sample number 

and size were appropriate; sample collection and handling was appropriate and documented; 

analytical facilities were adequate; IMO or ETV (v. 5.1) challenge conditions were met; if 

necessary, toxicological studies were conducted and demonstrated environmental safety; a 

QA/QC policy was in place and followed; and ultimately, land-based testing produced 

credible results.

• Shipboard testing was conducted with the same considerations as land-based testing 

(described above) and produced credible results.

• If an active substance was included, the BWMS had credible toxicity and chemistry data and 

G9 Basic approval or G9 Final Approval (which requires Basic approval).

• The BWMS had a type approval certificate.

• The BWMS was in operational use (i.e., not used only during shipboard type approval 

testing) on one or more active vessels. A BWMS not yet having operational systems onboard 

vessels was not automatically categorized as having “unreliable” data, but this information 

was useful. 

It is important to note that if the data packages were deemed “reliable, it was assumed that all protocols 

and methods were followed exactly as described. For data packages that included clear QA/QC 

procedures, there was a higher level of certainty that this was the case. In the absence of QA/QC 

documentation, which was the case for most data packages, the level of rigor in following the protocols 

and methods described was unknowable. 

4.4. Assessing the Ability of BWMS to Meet Discharge Standards

For BWMS with reliable data, the system’s ability to meet four discharge standards—IMO D-2/ USCG 

Phase 1 and 10x, 100x, and 1000x more stringent than IMO D-2/USCG Phase 1—was determined, again 

independently, by the three primary reviewers. 

• 10x was evaluated based on BWMS ability to reduce concentrations of living organisms: (a) 

≥50 μm in minimum dimension to below 1 per m3

, (b) ≥10 to <50 μm in minimum 

dimension to below 1 per ml, and (c) a decrease in total bacteria. 

• 100x was evaluated based on BWMS ability to reduce concentrations of living organisms: (a) 

≥50 μm in minimum dimension to below 1 per 10 m3, (b) ≥10 to <50 μm in minimum 

dimension to below 1 per 10 ml, and (c) and a significant reduction in total bacteria. 

• 1000x was considered the equivalent of the USCG Phase 2 standard, including: (a) ≥50 μm 

in minimum dimension to below 1 per 100 m3

, (b) ≥10 to <50 μm in minimum dimension to 

below 1 per 100 ml, (c) total bacteria below 10 per ml, (d) total viruses below 100 per ml, 

and below levels listed for indicator microbes (see Table 2-1).

The following scores and interpretations were assigned:

A - Demonstrated to meet this standard in accordance with the approach suggested in the IMO 

G8 guidelines (and G9 guidelines, if the BWMS employs an active substance).

B - Likely to meet this standard if the more detailed ETV Protocol (and corresponding sample 

volumes) were to be used.

C - May have the potential to meet this standard with reasonable/feasible modifications to the 

existing BWMS.
32

D - Unlikely, or not possible, to meet this standard, even with reasonable/feasible modifications 

to the existing BWMS.

To date, all BWMS adjudged to have reliable data have been tested in accordance with the G8 

guidelines, which provide only general recommendations for how to evaluate performance with respect 

to the D-2 standards. In late 2010, EPA’s Environmental Technology Verification (ETV) Program 

released the Protocol for the Verification of Ballast Water Treatment Technologies (Version 5.1, EPA 

2010). Although no BWMS has yet been tested under the ETV Protocol, this protocol provides much 

more detailed instructions for how to conduct BWMS tests that are scientifically rigorous and 

statistically sound. In particular, the ETV Protocol has significantly improved sampling procedures. The 

IMO G8 guidelines suggest collecting replicate samples with volumes of at least 1 m3 for the size class 

of organisms ≥ 50 μm in minimum dimension (nominally zooplankton). ETV, and others have 

demonstrated that a time-integrated sampling approach with larger sample volumes will increase 

statistical confidence regarding whether zooplankton in sparse populations meet or exceed the IMO D2/Phase 1 standard (Miller et al. 2011; Lee et al. 2010; section 3, above). As such, although D-2 and 

Phase 1 standards are essentially the same, some BWMS were given a score of ‘A’ if the data showed 

they met the D-2 standard by following the G8 guidance, and received a ‘B’ for Phase 1 if the number of 

living organisms was consistently low and it seemed very likely the BWMS would still meet the 

standard if ETV Protocols (including larger, integrated samples) were used. 

Regarding the discharge standard 10x more stringent than the IMO D-2/ Phase 1, the criterion used was 

whether the number of living organisms in all size classes was consistently low following testing (below 

the detection limit, often reported as zero, or not more than twice the standard). If so, the BWMS was 

given a ‘C’, indicating it had the potential to meet the standard. However, as described in the response to 

charge question 4 (Section 6), current testing methods do not provide the resolution required to conclude 

that 10x standards can be met. 

For the most stringent standards, 100x and 1000x more stringent than IMO D-2/ Phase 1, if any living 

organisms in any size class were found following treatment, the BWMS earned a ‘D’. This score 

indicates that it is extremely unlikely (or perhaps impossible) that the BWMS could meet a stricter 

standard, again because the detection limit of the test methods used provide resolution to IMO D-2/

Phase 1, at best. For example, if one viable zooplankter was found in testing using volumes of 1 m3

, the 

BWMS would be required to reduce the number of viable zooplankters to less than one in 10 m3 or 100 

m3 to meet the 100x and 1000x standards, respectively.

After each subgroup member completed his or her individual, independent assessments, they discussed 

their scores collectively. All scores from the three primary reviewers were found to be identical and in 

complete agreement with general assessments by the two subgroup oversight members, as well as other 

members of the entire Panel. These consensus findings were used to create Table 4-1. Rather than 

present the scores from individual, commercial BWMS units or models, the Panel categorized the 

technologies by operation type (e.g., filtration + UV). The operation types were chosen from recently 

published, third-party data reports (Albert et al. 2010; CSLC 2010; Lloyd’s Register 2010) in order to 

encompass all currently available operation types and to provide a standardized terminology. Thus, 

while the data packages from individual BWMS were initially examined and scored, the results were 

aggregated to represent a top-order status of the field. For a given operation type, if reliable data were 

available for more than one commercial BWMS, the scores given to the operation type were the highest 
33

scores of any of the individual BWMS. In this manner, Table 4-1 represents the greatest potential for 

each of the operational categories of technologies to meet various discharge standards. 

1
34

Table 4-1. Performance of Ballast Water Management Systems

Type or Category of BWMS # BWMS # Type Approval Cert # Available/Reliable Data D-2 P-1 10x 100x 1000x

Deoxygenation 2 0 0

Deoxygenation+cavitation 1 1 1 A B C D D

Deoxygenation+bioactive agent 1 0 0

Electrochlorination 2 1 0

Electric pulse 1 0 0

Filtration 1 0 0

Filtration+chlorine 2 0 0

Filtration+chlorine dioxide 1 0 1 A B C D D

Filtration+coagulation 1 1 0

Filtration+UV 10 3 3 A B C D D

Filtration+UV+Ti O2 1 1 1 A B C D D

Filtration+ultrasound 1 0 0

Filtration+ozone+ultrasound 1 0 0

Filtration+UV+ozone 1 0 0

Filtration+electrochlorination 5 1 2 A B C D D

Filtration+UV+ozone+ 

electrochlorination 1 0 0

Filtration+electrochlorination+ 

advanced oxidation 1 0 0

Filtration+cavitation+ 

electrochlorination 1 0 0

Filtration+-electrochlorination+ 

ultrasound 1 0 0

Filtration+cavitation+ozone+ 

electrochlorination 1 1 0
35

Type or Category of BWMS # BWMS # Type Approval Cert # Available/Reliable Data D-2 P-1 10x 100x 1000x

Filtration+plasma+UV 1 0 0

Filtration+cavitation+nitrogen+ 

electrochlorination 1 1 0

Filtration+hydrocyclone+ 

electrochlorination 1 0 0

Heat 1 0 0

Hydrocyclone+filtration+

peracetic acid ** 1 1 1

Hydrocyclone+

electrochlorination 2 0 0

Hydrodynamic 

shear+cavitation+ ozone 1 0 0

Hydrocyclone+filtration+UV 1 0 0

Menadione 1 0 0

Mexel 1 0 0

Ozone 1 1 0

Ozone+cavitation 1 0 0

Shear+cavitation+ozone 1 0 0

Shear+cavitation+peracetic acid 1 0 0

Totals 51 12 9

Green rows designate the types of BWMS that had reliable data and whose performance was evaluated against various discharge standards.

Based on one or more reliable data sets, the type of BWMS: 

(A) demonstrated to meet this standard in accordance with G8/G9

(B) likely to meet this standard if more detailed ETV Protocols were used

(C) potential to meet this standard with reasonable/feasible modifications

(D) unlikely, or not possible, to meet this standard

** Not scored because the one manufacturer has withdrawn this BWMS from market
36

4.5. Assessment Results

The results of this assessment are presented in Table 4-1 and interpretations of the findings are provided 

below. For this assessment, 51 individual BWMS were identified from prior reports (Albert et al. 2010;

CSLC 2010; Lloyds Register 2010) to show the breadth and diversity of treatment approaches. 

However, it is important to note that of the 51 BWMS listed, a large proportion are at early 

conceptual/development stages (only approximately 15 to 20 have been tested onboard an active vessel) 

and a few have recently been discounted because of logistic or performance challenges. The Panel 

received information packages on 15 individual BWMS, but just nine BWMS were considered to have 

reliable data for an assessment of performance.

4.6. Response to Charge Question 1

The analysis described above formed the basis of the Panel’s responses to charge Question 1a, 1 b, and 1 

c; each of these sub-questions addresses different aspects of treatment capabilities for shipboard 

systems. These questions and our responses are summarized below. 

Question 1a: For the shipboard systems with available test data, which types or categories have been 

evaluated with sufficient rigor to permit a credible assessment of performance capabilities in terms of 

effluent concentrations achieved (living organisms/unit of ballast water discharged or other metric)?

Conclusion 1a: Five types or categories of BWMS have been evaluated with sufficient rigor to permit a 

credible assessment of performance capabilities. These technology combinations are: 

• Deoxygenation + cavitation

• Filtration + chlorine dioxide

• Filtration + UV 

• Filtration + UV + Ti O2

• Filtration + electrochlorination 

Question1b: For those types or categories of systems identified in 1a, what are the discharge standards 

that the available data credibly demonstrate can be reliably achieved? Furthermore, do data indicate 

that certain systems (as tested) will not be able to reliably reach any or all of the discharge standards?

The five types of BWMS listed above have been demonstrated to meet the IMO D-2 discharge standard, 

when tested under the IMO G8 guidelines, and will likely meet USCG Phase 1 standards, if tested under 

the more detailed ETV Protocol. This level of treatment efficacy results in a 10,000x reduction in 

numbers of living organisms ≥ 50 μm in minimum dimension (under land-based testing guidelines). 

This represents an important achievement in the ability of these systems to effectively, reliably, and 

dramatically remove live organisms from ballast water under the challenging conditions found on active 

vessels.

The detection limits for currently available test methods and approaches prevent a complete statistical 

assessment of whether BWMS can exceed the IMO D-2/ Phase 1 standard. However, one way to predict 

the ability of a BWMS to meet 10x, 100x, or 1000x standards, is to consider the frequency with which 

any live organisms are detected during testing. This approach provides insight into BWMS 
37

consistency/reliability and its lower performance limits. Three frequency categories were defined using 

available data:

1. BWMS always produced “zero” or “non-detectable”: The system is consistently exceeding 

current detection limits and thus the IMO D-2/ Phase 1 standards (as described above).

However, if results for all test trials, for all categories of organisms, and for all samples from 

a specific BWMS reported “zero” or “non-detectable,” there is no way to determine if the 

system is performing just below the IMO D-2/ Phase 1 standards or if it is approaching 10x, 

100x or 1000x.

2. BWMS produced “zero” or “non-detectable” most of the time, with only one or a very few 

readings above the detection limit: The system appears to be operating near but below the 

IMO D-2/ Phase 1 standards. It is also possible that the occasional or rare “detects” were a 

result of BWMS malfunction or an error in sample collection, handling or analysis.

3. BWMS produced results in the detection limit most of the time, with only one or very few 

“zero” or “non-detectable”. The efficacy level of the system is clearly only at, or just below, 

the IMO D-2/ Phase 1 standards.

Not one of the BWMS examined could be categorized in group 1 (i.e., consistently scored “zero” or 

“non-detectable”). Instead, BWMS were roughly split between frequency categories 2 and 3. For all 

BWMS, live organisms in the ≥ 50 μm and/or ≥ 10 to < 50 μm size classes were detected in at least two 

independent test trials and in general, live organisms ≥ 10 μm were detected in 20% to 80% of test trials. 

It is also important to note that when total bacteria was quantified during the testing of BWMS, 

treatment did not reduce levels to that required in the 1000x discharge standard (10/ml). In fact, it was 

not uncommon to find an increase in total bacteria after treatment. Therefore, even if testing detection 

limits are improved, the lower performance limits of current BWMS are not expected to change. 

Conclusion 1b: The Panel concludes that five types of BWMS are currently able to reach IMO D-2/

Phase 1 standards. These same five types may be able to reach 10x IMO D-2/ Phase 1 standards for the 

≥50 μm and ≥ 10 to < 50 μm size classes in the near future, if both treatment performance and testing 

approaches improve (see Section 5). Finally, no current BWMS types can meet a 100x or 1000x 

discharge standard. 

Question 1c: For those systems identified above, if any of the system tests detected “no living 

organisms” in any or all of their replicates, is it reasonable to assume the systems are able to reliably 

meet or closely approach a “no living organism” standard or other standards identified in Table 4.1 of 

the EPA White Paper (June 2010), based on their engineering design and treatment processes?

To address this question, the phrase “no living organisms” was considered in two distinct ways: first, in 

a literal sense to mean the sterilization of ballast water and second, from a scientific perspective to mean 

results below method detection limits. 

Based on the test data provided for several BWMS, it is clear that numbers of live organisms in 

discharged ballast water are reduced dramatically relative to intake water and corresponding control 

water. Five distinct BWMS types have been demonstrated to meet the IMO D-2 standard and appear 

very likely to meet the USCG Phase 1standard (which demands, at minimum, a 4-log reduction from 
38

initial concentrations for the largest organism size class), not only in land-based testing but also under 

the physically challenging conditions presented on active merchant vessels during shipboard testing. 

However, even high levels of organism removal do not achieve sterilization or the complete removal of 

all living organisms. The identification of just one live organism would indicate non-sterile conditions, 

and all systems evaluated had at least one living organism in at least one treatment sample (and often 

more, as described above). Unfortunately, in some cases, this low number of live organisms might result 

from contaminated scientific sampling gear (nets, glassware, etc.) or human counting error. 

Alternatively, it is possible to establish specific detection limits (e.g., 100, 10, 1.0, 0.1, live organisms 

per m3 or ml) associated with the methods used to collect the current performance data available and 

thus to conclude that, if numbers of live organisms are below those detection limits, they are statistically 

indistinguishable from zero or no living organisms. Efforts have been made to calculate the probabilities 

of meeting such specified detection limits under certain assumptions, such as whether the organisms are 

randomly dispersed in space or spatially aggregated (see Lee et al. 2010 and Section 3 for details and 

examples). Not surprisingly, increased statistical power comes not only from increased sample size, but 

also from the difference between the mean established by regulation and the measured mean from a 

sample—which indicates the degree of compliance (or noncompliance). (See Section 3 for a more 

detailed discussion of sampling statistics and detection limits.) 

Conclusion 1c: It is not reasonable to assume that BWMS are able to reliably meet or closely approach 

a “no living organism” standard. Available data demonstrate that current ballast water management 

systems do not achieve sterilization or the complete removal of all living organisms.

4.7. Response to Charge Question 2 

Question 2: Based on engineering design and treatment processes used, and shipboard 

conditions/constraints, what types of ballast water treatment systems can reasonably be expected to 

reliably achieve any of the standards, and by what dates? Based on engineering design and treatment 

processes used, are there types or categories of systems that conceptually would have difficulty meeting 

any or all of the discharge standards?

A variety of BWMS types are being used to manage ballast water (Table 4-1). The data indicate that 

several types or categories are proving reliable and effective, and Table 4-1 lists five types that have 

been demonstrated to meet the IMO D-2/ Phase 1 standard. These five BWMS also appear to be mature 

technologies, with multiple active vessel installations, and are commercially available. Interestingly, 

four of the five treatment approaches include a filtration step, although the inclusion of filtration does 

not necessarily ensure that the BWMS will meet discharge standards. A large majority of BWMS also 

appear to be adapted from technologies long applied to water treatment.

Given the data available, it is reasonable to assume that these same five systems have the potential to 

meet a 10x IMO D-2/ Phase 1 standard in the near future (see Section 5). As noted above, the Panel 

makes this prediction based upon available data that show viable organisms sampled as low (usually, 

below detection limits) but improvements to test methods/approaches will be required to demonstrate 

conclusively that improved BWMS meet standards beyond IMO D-2/ Phase 1. Given the data available, 

it is highly unlikely that any of the systems listed in Table 4-1 could provide organism removal to the 

level of 100x or 1000x the standard because all systems showed at least one observation of a living 

organism within the sample volumes as specified in IMO D-2 guidelines, thus clearly exceeding these 
39

more stringent standards. No BWMS reported zero living organisms in all samples analyzed following 

treatment. In fact, most results showed an increase in total bacteria abundances after treatment, far 

exceeding discharge levels proposed in the USCG Phase 2 standards. Ultimately, different technologies 

or treatment approaches, and sampling strategies will be needed to achieve these higher levels of 

removal. At this time, it is not possible to comment on the likelihood that the other treatment types listed 

will, or will not, be able to meet either the IMO D-2/Phase 1 or more stringent standards. All the BWMS 

types listed in Table 4-1 have likely shown some potential for reducing the number of ballast water 

organisms, but for most the data available for examination were deemed either to be absent or 

unreliable. As such, it is not possible to predict the eventual performance of these BWMS.

Conclusion 2: Five types or categories of ballast water management systems can currently meet the 

IMO D-2 discharge standard and appear to meet USCG Phase I standard: Deoxygenation + cavitation;

Filtration + chlorine dioxide; Filtration + UV; Filtration + UV + TiO2; and Filtration + 

electrochlorination. It is possible that the same five types could meet 10x IMO D-2/Phase 1 sometime in 

the near future if both treatment performance and testing methods and approaches (e.g., detection limits) 

improve. Nearly all of the 51 treatment types or categories evaluated are based on reasonable 

engineering designs and treatment processes, and most are adapted from longstanding industrial water 

treatment approaches. However, the lack of detailed information on the great majority of BWMS 

prevents an assessment of limitations in meeting any or all discharge standards.

4.8. Environmental Effects and Vessel Applications: Additional Constraints and Considerations 

that Influence BWMS Performance 

BWMS are still evolving with an ever-growing number of manufacturers developing systems. Although 

several BWMS have received type approval certification, and appear to safely (e.g., received final G9 

approval) and effectively meet IMO D-2/Phase 1 discharge standards (Table 4-1), there are several 

factors to consider beyond mechanical and biological efficacy. Perhaps the four most important 

considerations for the broad applicability of BWMS are ambient water salinity (the ability to treat fresh, 

brackish, and marine water) and temperature (the ability to work effectively and safely in a variety of 

temperatures from warm equatorial to cold polar water), ship ballasting rate (the ability to treat water 

moving at a variety of flow rates from < 200 m3/hr to > 4,000 m3/hr), and ballast volumes (the ability to 

treat total volumes of ballast water from < 1,000 m3 to > 50,000 m3

). 

Another important vessel consideration is impacts of treatments on ballast tank and piping coatings and 

substrate corrosion rates. Nearly all systems that alter the chemical composition or reactivity of ballast 

water (e.g., heat, oxidants, and deoxygenation) can potentially affect corrosion of ship structures, piping, 

fixtures and protective coatings. To a great extent, the potential effects of these BWMS have not been 

consistently evaluated across the various modes of corrosion, including uniform or localized corrosion, 

or for potential interactions with corrosion control systems including protective coatings and cathodic 

protection systems. Some BWMS have provided data that indicate negligible impacts on corrosion rates 

or even improvements. For example, deoxygenation, if operated properly, can dramatically reduce 

uniform corrosion rates, but alternatively, deoxygenation may result in increased corrosion rates due to 

either the cycling of hypoxic and aerated conditions or the formation of corrosion-causing sulfate 

reducing bacteria if anoxic conditions are reached. Similarly, other BWMS utilizing strong oxidants 

have been evaluated as having apparently negligible effects on coatings and steel corrosion rates. 

However, it is also well documented in the water treatment and marine vessel industry that continuous 

exposure to high doses of some oxidants, such as halogenated oxidants, can cause severe corrosion rates 
40

(depending on the specific oxidant, its concentration and contact period). On the other hand, while 

heightened corrosion rates may be experienced shortly after treatment, corrosion rates on the whole may 

not be significantly affected if the oxidant concentration declines rapidly. 

Corrosion is already a significant concern for vessels operating in saltwater environments. As such, 

coating failures and steel wastage are currently incorporated into periodic surveys and vessel service 

periods. In the end, an increase in corrosion rates will impact the maintenance and repair costs borne by 

the vessel owner; these potential increases in cost will need to be factored by the owner in selecting a 

BWMS. In addition, corrosion control and mitigation strategies such as coatings and cathodic protection 

should also be carefully considered since either or both of these may be employed to offset any 

increased corrosion concerns. Although comprehensive assessments have not been conducted for all 

BWMS, no major damage or casualties related to corrosion have been identified to date for BWMS

installed on ships. 

In addition to specific environmental and vessel applications, vessel type and vessel operations can 

dictate BWMS applicability. Although a multitude of vessel designs and operation scenarios exist, a few 

important examples of specific constraints can greatly limit treatment options. Perhaps the most 

dramatic limitations are found with the Great Lakes bulk carrier fleet that operates vessels solely within 

the Great Lakes with large volumes of fresh, and often cold, ballast water (“Lakers”). The vessels in this 

fleet have ballast volumes up to 50,000 m3

, high pumping rates (up to 5,000 m3/hour), uncoated ballast 

tanks (older vessels), and some vessels have separate sea chests and pumps for each ballast tank. A 

further confounding issue is that voyages taken by Lakers average four to five days, with many less than 

two days. Given these characteristics, a number of limitations are imposed: electrochlorination and 

ozonation may only work in freshwater with the addition of brine (in particular Cl and Br, respectively); 

oxidizing chemicals may increase the corrosion rate of uncoated tanks; deoxygenation and chemical 

treatments that require holding times to effectively treat water (or for the breakdown of active 

substances) may not be completely effective on short voyages; and the space and power needed for the 

required numbers of filtration + UV treatments may simply not be available.

Another example of vessel-specific constraints is the sheer size of some vessels and the cargo they carry. 

Very Large Crude Carriers (VLCC) and Ultra Large Crude Carriers (ULCC) can carry up to 100,000 m3

of ballast and can fill or discharge ballast water at over 5,000 m3

/hour. While various BWMS may be 

modular (perhaps providing the ability to add several units in a manifold design or in sequence), systems 

that include a mechanical separation stage (e.g., filtration, hydrocyclone) or exposure to UV or 

sonication may have difficulty addressing these large volumes and flow rates. Furthermore, given the 

hazardous nature of the cargo carried on these ships (and other similar vessels, such as Liquefied Natural 

Gas carriers), restrictions on the placement of a specific BWMS may apply, and system components will 

likely have to satisfy classification society requirements for explosion-proof and intrinsically safe 

construction, which might be more difficult for some BWMS types than others.

A final example is the treatment of ballast water on the tens of thousands of unmanned barges in the 

U.S. that would fall under the ballast water discharge regulations. Inland waterways and coastal barges 

are not self-propelled, but rather are moved by towing or pushing with tugboats. Because these vessels 

have been designed to transport bulk cargo, or as working platforms, they commonly use ballast tanks or 

fill cargo spaces with water for trim and stability, or to prevent excessive motions in heavy seas. 

However, the application of BWMS on these vessels presents significant logistical challenges because 

they typically do not have their own source of power or ballast pumps and are unmanned.
41

Conclusion: While several BWMS appear to safely and effectively meet IMO D-2/Phase 1 discharge 

standards, there are several factors to consider beyond mechanical and biological efficacy. A variety of 

environmental (e.g., temperature and salinity), operational (e.g., ballasting flow rates and holding times), 

and vessel design (e.g., ballast volume and unmanned barges) parameters will impact the performance or 

applicability of individual BWMS.
42

5. SYSTEM DEVELOPMENT

5.1. Introduction

This section addresses issues related to potential future improvements in BWMS in response to charge 

question 3, which focuses on three main issues: improving the performance of existing BWMS 

technologies, identifying impediments to improved technological performance, and considering whether 

technologies can achieve zero or near-zero discharge of organisms. 

Before considering possible improvements, it is important first to consider what has been achieved to 

date by existing BWMS technologies. The 2004 IMO D-2 standard has provided a stable target for 

research, development, testing, and evaluation of practices and technologies to treat ballast water. Using 

the proposed D-2 standard as a design goal, some developers of BWMS have:

• Integrated BWMS within marine vessel arrangements, weight and stability constraints, 

electrical distribution and piping systems, and automated control systems. 

• Integrated the operation of BWMS within the larger context of merchant vessel operations 

such as ballasting rates and volumes, logistics requirements such as reliable chemical-supply 

chains and service/support centers, safe operations such as hazardous-rated equipment and 

chemical-handling procedures, and operational training. 

• Tuned BWMS to achieve acceptable levels of disinfection by-products, residual toxicity, 

within the limits of practicality and in compliance with the proposed D-2 standard.

• Packaged the technology for a competitive commercial market, which requires consideration 

of life-cycle costs, reliability of equipment, maintenance issues, and acceptance of the 

BWMS technologies by mariners. 

These are important achievements. They also foreshadow the issues that must be considered when 

evaluating technological options to improve BWMS technologies.

In general, technological changes to improve BWMS performance will proceed along one of two paths: 

(1) incremental changes to existing designs with the goal of optimizing performance, or (2) designing 

entirely new treatment methods. Incremental changes offer the faster path to improved performance, but 

are likely to achieve only relatively modest improvements. Wholly new approaches for BWMS, possibly 

drawn from the water treatment industry, also would improve performance—perhaps significantly—but 

would take more time to develop and test in order to determine performance, practicality, and costeffectiveness. The Panel considers both pathways below. 

5.2. Improving the Performance of Existing Systems

Charge question 3a. For those systems identified in questions 1.a and 2, are there reasonable changes 

or additions to treatment processes which can be made to the systems to improve performance? 

The Panel defined “reasonable changes” as incremental adjustments or improvements that do not 

fundamentally alter the treatment process. For example, design changes to increase UV radiation 

intensity would be an incremental adjustment, whereas addition of a UV stage would not. In practice, 

“reasonable changes” mean the same thing as “incremental improvements.” Both are based on the 
43

concept of “turning up the dial” on existing technologies rather than creating wholly new systems or 

adding processes to the treatment system. Although incremental changes can generally be implemented 

more quickly, this approach is not necessarily simple or foolproof. First, it may be impossible or 

impractical to further improve the baseline technology. Second, any changes could fundamentally alter 

other aspects of the technology’s performance or use; e.g., it could change its life cycle costs, affect 

integration of the BWMS with vessel operation, or increase residual toxicity of ballast water discharges. 

As described in Section 4.4, five BWMS have demonstrated compliance with IMO D-2 standards, under 

G8 testing conditions. Based on information from available test results, incremental improvements could 

be made to these treatment processes, perhaps yielding performance greater than D-2. However, these 

changes may add costs and engineering complexity. 

Examples of incremental improvements to the BWMS judged to comply with the D-2 standard, as 

shown in Table 4-1, are summarized below. 

• Deoxygenation + cavitation. Current technology for these systems establishes severe 

hypoxia, which kills larger organisms very effectively, although hypoxia has little or no 

effect on some bacteria, pathogenic protozoa, or viruses. It is not possible to improve on 

hypoxic conditions per se, however, it may be possible to reduce the time needed to reach 

severe hypoxia and increase holding time under severe hypoxia. In addition, effectiveness 

might be improved by increasing the degree of cavitation and physical/mechanical disruption 

of organisms.

• Mechanical separation + oxidizing agent. These systems could be optimized in several 

ways: improved mechanical separation (i.e., filtering) to remove higher percentages of 

particles and particles of smaller size; increasing the concentration and contact time for 

oxidizing agents; and adjusting other water chemistry parameters, such as pH, to increase the 

efficacy of the oxidizing agent. (Note: this category corresponds to those BWMS using 

filtration and chlorine dioxide, filtration plus UV + TiO2, and filtration plus 

electrochlorination).

• Mechanical separation + UV. These systems could be optimized by improved mechanical 

separation (i.e., filtering) to remove higher percentages of particles and particles of smaller 

size and by increasing UV contact time and dosage.

5.2.1. Combination Technologies

Most ballast water treatment systems, even those with a single primary component, are actually 

combination technologies. For example, one company’s BWMS relies primarily on deoxygenation, but 

also has a venturi device that mechanically damages some of the organisms (as would cavitation) and 

uses carbon dioxide, which forms carbonic acid, lowering the pH of the water. Another commercial 

system is advertised as a combination technology that includes filtration, ultraviolet radiation, and

treatment by free radicals.

It is difficult to fully understand the interactions of treatment processes used in combination BWMS. 

This makes it hard to predict the overall treatment effect of incremental improvements within individual 

processes. For example, one company’s system combines filtration, cavitation, ozone, and sodium 
44

hypochlorite. With four “primary” technologies at work, which should be the focus for “turning up the 

dial” to improve performance? Further complicating matters is the great variability in the physical and 

chemical properties of ballast water itself, which in turn creates complex interactions with individual 

treatments as well as their combination. 

To date, combination BWMS have been developed through research and testing. However, once a 

technology has shown promise to meet the D-2 standard, its development is stopped to allow the device 

to undergo certification testing. It is reasonable to assume that incremental improvements to 

combination technologies could yield efficiencies in operation (less power, less cost, more reliability) 

and moderate improvements in treatment effectiveness. Due to the complex interactions among 

combined treatment processes, however, such possibilities can only be speculative until a more rational 

understanding of the modes of inactivation/kill is developed and verified by experiments with 

prototypes. Thus, the Panel’s comments on likely improvements to BWMS technologies are restricted to 

the primary treatment processes identified in Section 4 and described below: UV radiation, mechanical 

separation + cavitation, deoxygenation, and oxidant based systems. Other BWMS processes, such as 

ultrasound and electro-mechanical separation, are not as widely utilized and therefore were not 

reviewed.

5.2.2. UV Radiation

There are several ways in which treatment by UV radiation may be improved. It may be possible to 

deploy “over-sized” UV radiation treatment systems to improve performance. For example, a ballast 

system that runs at 800 m3

/hr could be paired with a treatment system rated for 1,000 m3/hr, thereby 

presumably increasing UV exposure by 20 percent. Testing and analysis would be required to determine 

if efficacy was actually increased and, if so, by how much, and to ensure there were no adverse impacts 

to the residence time distribution or UV intensity field distribution of the UV chamber. 

Similarly, UV system performance might be improved through increased intensity of UV lamps. The 

length of time the ballast water is exposed to UV radiation could also be increased by increasing the size 

of the chamber relative to the ballasting rate. Such improvements, however, would increase the size and 

cost of BWMS equipment.

UV chambers could also be staged in series, though this would substantially increase cost, required 

space, and maintenance. However, employing multiple UV chambers in series could provide the 

following improvements to performance:

• Decreased chance that organisms could “slip” past untreated, assuming that each chamber 

could independently provide treatment adequate to meet a given standard.

• Increased time during which organisms are exposed to UV. 

The performance of UV systems also could be improved by using more effective mechanical separation 

methods (“filtering”) upstream of the UV chambers in order to enhance the transmissivity (clarity) of the 

ballast water prior to UV treatment. Flocculants such as alum could further clarify the ballast water, 

providing that these agents do not impart UV absorbance (as may be the case with iron-based 

flocculants). Such improvements have drawbacks. For instance, advanced mechanical separation would 

significantly increase costs and space requirements, and would likely significantly increase backpressure 
45

within the system, resulting in higher electrical power demands and a need for higher-head ballast 

pumps. 

5.2.3. Mechanical Separation and Cavitation

Many BWMS use mechanical separation as the primary precursor for other treatments such as UV 

radiation or oxidants. The purpose of mechanical separation varies according to the treatment’s 

disinfection processes: e.g., screening to remove larger organisms resistant to disinfection, reduction of 

organic matter to reduce oxidant demand, and reduction of turbidity to increase transmittance of UV 

radiation. 

Mechanical separation also has a secondary effect—physically damaging some of the organisms as they 

pass through the device—which may inactivate or kill organisms or weaken their cellular structure such 

that effective disinfection is more easily achieved. In this regard, mechanical separation is similar to 

cavitation devices designed to impart physical damage to organisms. Some BWMS include cavitation 

devices to damage cellular structure without having to handle separated filtrate.

Use of seawater filtration on vessels traditionally has been limited to protecting mechanical devices in 

the piping system. For example, seawater might be “screened” to a one-eighth inch opening (3.175 mm) 

to protect the narrow passages of a heat exchanger. Recently, however, several common and proprietary 

devices have been developed for filtering and imparting cavitation effects on ballast water as part of the 

treatment process: variations on back flushing of traditional screen filters; vibrating disc filters; multi 

hydro-cyclone; and various cavitation devices. In general, the filter units target removal of particles 

above 40 or 50 μm and have significant waste streams that are returned to the ambient water. Typically, 

filtering takes place on ballast water uptake only.

Mechanical separation devices are advertised in terms of percentage removal. For example, two 

companies claim filtration rates of approximately 90 percent removal of zooplankton. These removal 

levels, although essential to support the disinfection process, by themselves are far from adequate to 

meet the D-2 standard for the size class > 50 μm.

In summary, it is not reasonable to expect incremental improvements in mechanical separation devices 

to achieve significant advances in performance over the D-2 standard. Such improvements would 

require use of media filters, membrane filters, or other devices that have not yet been practically applied 

to ballast water treatment. Similarly, cavitation devices alone cannot meet the D-2 standard. It is not 

clear if improvements to cavitation devices will significantly increase the effectiveness of BWMS that 

employ combined processes.

5.2.4. Deoxygenation

Two Type-Approved BWMS that have met the D-2 standard use deoxygenation as part of multiple 

treatment processes. The first system lowers oxygen by pumping low-oxygen gas from a purpose-built 

burner into the BWMS through a venturi device. The efficacy of this system relies on several 

interrelated components: rapid application of the gas stream; creating carbonic acid from the carbon 

dioxide in the gas stream, which lowers pH and makes the low-oxygen environment more lethal; and the 

mechanical effect of the venturi on passing organisms. 
46

This system lowers the oxygen level to about 2 percent by volume (about 0.7 mg/L) by using a variation 

on the traditional tank-ship combustion-based inert-gas generator. Traditional units produce a 5 percent

oxygen level (about 1.8 mg/L). For reference, 2 mg/L oxygen is considered the upper boundary for 

environmental hypoxia and the point of mortality for sensitive species. Very few metazoans can survive 

<1 mg/L oxygen for longer than 24 hours (Vaquer-Sonyer and Duarte 2008). Further improvements to 

combustion-based units may not be practical given constraints of the combustion process. 

The second system lowers oxygen levels through use of a nitrogen generator. The generator uses a 

membrane to filter ambient air, resulting in high quality nitrogen gas. The system also uses mechanical 

separation, cavitation and electrodialytic disinfection. Nitrogen generators are widely deployed in 

industry and in some marine applications. On ships, they are generally regarded as expensive, highdemand consumers of electrical power. It is possible to create very high quality nitrogen gas, 

approaching 99.9 percent pure, but doing so requires significant space, capital costs, and high electrical 

power demands. 

As these examples show, BWMS that use deoxygenation often also use additional treatment processes. 

Thus, it is difficult to predict the effect of incremental improvements on overall efficacy. In fact, some 

changes might decrease efficacy, or worse, result in unanticipated adverse conditions; e.g., higher 

populations of sulfate-reducing bacteria and subsequent increase in steel corrosion rates. Consequently, 

it is not possible to assess whether incremental improvements will yield higher performance. For 

example, with respect to treatment lethality to metazoans, there is little to no difference between oxygen 

levels of 2 mg/L and 1 mg/L for the same contact period. Extending holding time would be more 

efficient than additional efforts to reduce oxygen below 1 mg/L. However, there is some evidence 

(Mario Tamburri, pers. comm.) that faster transitions to severe hypoxia are more lethal.

5.2.5. Oxidant-Based Systems

Oxidant-based systems introduce an oxidizing agent (such as chlorine) into the ballast water stream. 

These systems are generally designed to target a given level of total residual oxidant (TRO) in the 

treated ballast water. Oxidant-based systems pose issues for mechanical integrity and for worker safety, 

since these systems require adding chemicals in bulk, on-site manufacture of sodium hypochlorite or 

similar chemicals, or on-site production of ozone gas. 

The consumption (or oxidant demand) of the introduced oxidant varies with the organic-matter content 

of the ballast water uptake. After the initial instantaneous consumption of oxidant, any remaining 

oxidant is pumped with the ballast water into the vessel’s ballast tanks. There it is held for a prescribed 

length of time at the TRO concentration. The TRO level will decay over time as a function of many 

factors, including its initial concentration, salinity, temperature, motions of the vessel, and configuration 

of the ballast tank and venting system. Depending upon the predicted or measured oxidant levels in the 

ballast water, a neutralizing agent may be applied before or during its discharge to the environment.

The effectiveness of oxidant-based systems is a function of the concentration of the residual oxidants 

and the holding time. Incremental changes that could improve effectiveness include: increasing initial 

oxidant concentrations; maintaining a higher oxidant concentration during the holding period; and 

increasing the holding period or contact time. The potential for improved performance for each of these 

three options are considered below (the use of oxidants in combination BWMS treatments is considered 

separately).
47

Increasing Initial Oxidant Concentrations

Determining the initial oxidant concentration needed to reach the required efficacy is part of the “art” of 

a BWMS. For example, TRO values for BWMS that the Panel reviewed varied in the type of oxidant 

used (e.g., ozone, chlorite ion, free active chlorine) and TRO amounts varied by an order of magnitude. 

Several oxidant-based systems also use some form of mechanical separation to remove larger organisms, 

organisms entrapped within protective solids, and some particulate organic matter and thereby reduce 

oxidant demand. Regardless of the effectiveness of the mechanical separation, however, it is the residual 

oxidants and other reactive disinfection byproducts that achieve the final treatment performance. Thus, 

even though mechanical separation may reduce the amount of chemical required, it is unlikely to 

improve the efficacy of the oxidant. Tertiary effects also occur, such as damage to organisms’ 

membranes during mechanical separation and subsequent membrane interaction with oxidant-based 

systems. However, these tertiary effects are difficult to assess. Thus, they do not represent an obvious

method for incremental improvement.

However, it is possible to “turn up the dial” on existing BWMS by increasing the amount of oxidant 

used, which should improve effectiveness. Doing so simply requires that a higher capacity ballast water 

treatment system be installed. For example, concentrations could be increased 50 percent by installing a 

system rated for 1200 m3

/hr on a vessel that pumps ballast water at 800 m3/hr. Such an installation will 

demand larger space and weight allowances, more power, and higher capital and operating costs. In 

general, it should be possible to integrate higher capacity systems for new vessel designs, but it is more 

of a challenge to retrofit on existing vessels.

Higher oxidant levels in ballast water can have a significant negative effect impact on piping-system 

components and tank-coating systems. Valve packing, flange gaskets, and pump seals are made of a 

variety of materials, some of which are not compatible with oxidants at low concentrations, and less so 

at increasingly higher concentrations. Impacts on tank coatings are not yet well understood. TRO levels 

up to 10 mg/L may be compatible with typical intact ballast-tank marine coatings. However, coatings 

are frequently not intact, because they wear over time. In the case of freshwater shipping, a ballast water 

tank may not be coated at all. Corrosion of exposed carbon-steel structures can lead to structural failures 

and require expensive and complex repairs. Use of increased oxidant levels, therefore, would likely 

increase rates for coating failures and corrosion of exposed carbon-steel structure.

Use of higher oxidant levels also increases concerns for safe handling on board vessels, due to the need 

for handling and storage of additional bulk chemicals, lengthening the time required to make confined 

tank spaces safe for entry for inspection and repair work, and generation of hydrogen gas. These 

concerns can be handled through operating procedures but at the expense of increased time and effort. 

As higher levels of oxidants are introduced into ballast water, complex chemical reactions take place, 

resulting in potentially harmful disinfection byproducts through interactions between the oxidant level 

and characteristics of the uptake water (such as its organic load, alkalinity, salinity, and chemical 

contaminants). Further tests and analysis would be required to determine whether these byproducts 

should and can be neutralized so that the ballast water discharge will meet acceptable toxicity limits. 
48

Maintaining Increased Oxidant Concentrations

Most oxidant-based systems rely on achieving residual oxidant levels that are adequate to meet D-2 

standards and then maintaining that concentration for the duration of the holding period. The hold time 

of ballast water can vary significantly, however, and shipping schedules, weather, equipment failure, and 

cargo-handling changes frequently result in hold times that are longer or shorter than initially expected. 

As hold times increase, TRO concentrations decay, which also reduces detoxification costs. Most 

evaluation testing occurs during a prescribed holding period, typically for two to five days. In reality, 

ballast water hold times routinely vary from one day to several weeks. In fact, some ballast tanks can 

remain full, or partially full, for many months or even years.

There has been little development or testing of systems that monitor and maintain a specific oxidant 

level in ballast water tanks. Indeed, automated monitoring of oxidant levels in ballast water tanks is not 

currently practiced. Continuous or periodic monitoring would require either a network of sensors 

installed in the tanks or a means of drawing a liquid sample on a periodic basis to a remote monitoring 

device. Such sensors are common practice in the treatment of drinking water and wastewater. Either 

approach requires significant cabling, possibly tubing and pumps, monitoring equipment, and datarecording devices.

Current practice to maintain oxidant levels, if done at all, is to “top up” a ballast tank; i.e., to partially 

discharge its contents, then refill the tank with freshly treated water. The objective is to achieve the 

desired oxidant level by mixing the “new” water having a high concentration of oxidant with the water 

remaining in the tank. Under such conditions, it is imprecise to determine whether desired inactivation 

levels are achieved. Such efforts are similar in mechanical function to ballast water exchange, would 

likely be performed while the vessel is at sea, and carry with them the same significant safety concerns 

regarding vessel stability. A safer and more reliable approach for topping up oxidant levels would 

require developing new systems. Such systems might include chemical dosing lines to deliver an 

external supply to each ballast tank, combined with circulation devices internal to each ballast tank.

Increasing the Hold Period

Increasing the hold time of the ballast water while maintaining a certain oxidant level would likely 

increase treatment efficacy. However, it is ship operations that will dictate the duration of this hold time 

for most ballast water tanks. In particular, the largest mid-body ballast water tanks almost always have 

to be discharged while tank ships or bulk carriers are being loaded. As such, the treatment process must 

account for the expected hold period, but likely will not have the ability to alter it.

Summary of Oxidant-Based Treatments

Existing oxidant-based systems have been developed to meet the D-2 standard, and several have 

received international approvals. Their efficacy could be improved by increasing initial residual oxidant 

levels in ballast water during uptake. However, testing would be needed to determine the degree of 

improvement and to determine toxicity effects from disinfection byproducts resulting from higher 

oxidant doses. 

Increasing residual oxidant levels also creates demands for space, weight, power, and capital and 

operating expenses; in addition, these systems will increase piping-system compatibility issues, ballast-
49

tank corrosion rates, and safe-handling concerns. Alternatively, it may be possible to increase 

effectiveness by maintaining residual oxidant levels during holding time in the ballast water tanks. 

Current systems, however, have only rudimentary methods for performing such operations. New 

methods will need to be developed and tested to determine their practicality and effect.

5.3. Principal Technological Constraints

Charge question 3b. What are the principal technological constraints or other impediments to the 

development of ballast water treatment technologies for use onboard vessels to reliably meet any or all 

of the discharge standards? 

Existing BWMS have been developed to the IMO D-2 standard within the context of typical marine 

vessel constraints, including restrictions on size, weight and energy demands. While practical for new 

construction vessels, existing vessels may not be able to integrate such BWMS on a retrofit basis. 

Meeting higher standards generally implies that the treatment processing plants will need to be large, 

heavy, energy-intensive and expensive. At some point, constraints associated with the installation and 

operation of such equipment may require a fundamental shift in how ballast water is managed. 

Regardless of the applicable treatment standard, existing and potential BWMS share common 

impediments to development. 

(a) Technical constraints include:

• The shipboard marine environment is corrosive and subject to vibrations and ship motions. 

Thus, one should not assume that shore-side systems can be transferred easily to shipboard 

use; in fact, a strong shipboard service history will be an important guide to selecting system 

components. Even so, the characteristics of water in some non-ballast water shipboard 

applications may differ from ballast water (e.g., sediment concentrations may be greater in 

ballast water). This makes it difficult to predict performance based on service history alone.

• Vessels are initially designed to have ballasting capabilities and procedures that meet their 

intended service and voyage profile. BWMS intended for retrofit will need to fit within those 

original parameters. 

(b) Other impediments include:

• Lack of clear design goals. There is disagreement on discharge standards; they vary from 

state to state within the U.S. and internationally. Thus, BWMS manufacturers have multiple 

discharge standards as design targets. Further, there are no established compliance 

monitoring, enforcement procedures. Such procedures would help focus future BWMS 

development; e.g., they would encourage the creation and use of additional performance 

metrics, such as system reliability, as contrasted with the current focus on discharge quality 

as evaluated during certification testing. 

• Limited experience and limited empirical data on life-cycle costs. The full cost of any 

BWMS includes not only its initial purchase and installation costs, but also its long-term 

operational costs. System reliability, durability, cost of spares, and ease of maintenance are 

factors that contribute to determining the BWMS life-cycle costs. 
50

(c) Constraints to improved performance include:

• Shipboard BWMS are developing rapidly. The focus to date has been engineering the 

treatment device for discharge performance. This focus has come at the expense of ensuring 

integration of the BWMS with vessel mechanical systems and marine operational activities; 

BWMS durability, maintenance and repair; training; and procedures for monitoring 

technology performance. 

• Ships crews are small in number and busy; therefore, any new system must be easy to 

operate and maintain. Ideally, new systems would enable remote control from the ballast 

control console and automatic operation in or near port, which is typically a busy time for 

crew. 

• Most importantly, BWMS should pose no unreasonable health risk for the crew nor create 

higher risk for vessel safety, and require no exceptions to the safety procedures established 

by the vessel owner. The BWMS installation and operation procedures must also meet the 

requirements of control authorities, i.e., Classification Society, Flag State, and Port State. 

• Facilities properly equipped to test BWMS technologies are few, which imposes a bottleneck 

to swift verification and testing and thus hinders development. Increased sharing of data and 

specific protocols among such facilities is essential.

5.3.1. Operational Challenges on Working Merchant Vessels

It is unlikely that current BWMS will be able to meet the most stringent proposed standards (e.g., 100x

D-2 or 1000x D-2). This is perhaps best understood in the context of required reductions in organisms. 

Meeting the D-2 standards for zooplankton-sized organisms requires that the BWMS reduce the number 

of zooplankton in challenge water (as defined by the EPA ETV program) by four orders of magnitude. 

For a very large crude carrier (VLCC) tanker carrying roughly 90,000 m3 of ballast water, the D-2 

standard would require reducing the number of zooplankton-sized organisms from 9 billion to 900,000 

(Table 5-1). The USCG’s proposed Phase 2 standard for zooplankton (in the column labeled “D-2/1000” 

in Table 5-1) would require that BWMS reduce viable zooplankton by seven orders of magnitude 

relative to values in ETV challenge water. (This is a 99.99999 percent reduction, referred to in reliability 

engineering as “seven-nines”). For the VLCC example, the proposed Phase 2 standard would limit the 

discharge of viable zooplankton to a maximum of 900 individuals (Table 5-1). To put this value in 

perspective, it is fewer than half the number of zooplankton (2000 individuals) contained in a 20-liter 

bucket of ETV challenge water (Table 5-1). Additional examples of allowable zooplankton discharges 

associated with different discharge standards and for different types of vessels are summarized in Table 

5-1, below.
51

Table 5-1. Zooplankton Counts for Water and Increasing Log Reductions from D-2 Standard. The USCG’s 

proposed Phase 2 standard is represented by in the column labeled “D-2/1000”.

Volume Rate Viable Organisms >50 um (Seawater per US ETV)

Volume Basis (m3) (m3/hr) Seawater IMO D-2 D-2 x 10 D-2 x 100 D-2x1000

Test Standards 1.00E+00 NA 1.00E+05 1.00E+01 1.00E+00 1.00E-01 1.00E-02

VLCC Tanker 9.00E+04 5.00E+03 9.00E+09 9.00E+05 9.00E+04 9.00E+03 9.00E+02

Great Lakes Bulk Carrier 4.40E+04 1.00E+04 4.40E+09 4.40E+05 4.40E+04 4.40E+03 4.40E+02

Handymax Bulk Carrier 1.80E+04 1.30E+03 1.80E+09 1.80E+05 1.80E+04 1.80E+03 1.80E+02

Panamax Container 1.70E+04 5.00E+02 1.70E+09 1.70E+05 1.70E+04 1.70E+03 1.70E+02

Feedermax Container 3.50E+03 4.00E+02 3.50E+08 3.50E+04 3.50E+03 3.50E+02 3.50E+01

Passenger Ship 3.00E+03 2.50E+02 3.00E+08 3.00E+04 3.00E+03 3.00E+02 3.00E+01

ETV Testing Tank 2.00E+02 2.00E+02 2.00E+07 2.00E+03 2.00E+02 2.00E+01 2.00E+00

VLCC Pipe (2.2 meters) 1.39E+00 5.00E+03 1.39E+05 1.39E+01 1.39E+00 1.39E-01 1.39E-02

Bucket (20 liters) 2.00E-02 NA 2.00E+03 2.00E-01 2.00E-02 2.00E-03 2.00E-04

Glass (0.4 liters) 4.00E-04 NA 4.00E+01 4.00E-03 4.00E-04 4.00E-05 4.00E-06

Table 5-1 expresses zooplankton treatment standards as maximum allowable numbers of viable organisms for various 

volumes. The top row (“Test Standards”) provides organism counts in 1 m3 of ETV challenge water (column labeled 

“Seawater”), and maximum allowable counts in 1 m3 of water meeting the IMO D-2 standard and successive log reductions 

beyond D-2. Several vessel types are listed showing their typical ballast-water volumes and discharge flow rates. For each 

volume, the table shows the number of organisms it contains (column labeled “Seawater”) and the maximum number of 

organisms allowed by each of the discharge standards. 

Table 5-1 also indicates the number of zooplankton in volumes of ETV challenge water equivalent to a beer glass, a bucket, 

and that displaced by one second of untreated discharge from a VLCC. The colored highlights indicate when the glass, 

bucket, or discharge contains more viable organisms than those in the total volume of water discharged from a vessel in 

compliance with the various standards. 

In contrast, incremental adjustments to existing technologies are expected to result in only slightly 

greater reductions of viable organisms in BWMS discharge. In part, the inability to achieve huge 

reductions stems from the design characteristics of present-day BWMS technology, which is placed “on 

top of” existing ballast-piping systems. The treatment devices (e.g., filters, UV lamps, cavitation 

devices) are added to the standard ballast-piping, which was originally designed solely for the efficient 

uptake and discharge of ballast water. Further, ballast water is still taken up, held, and discharged in 

essentially the same manner as in the past. 

It is also instructive to consider the challenges of meeting the proposed, more stringent standards within 

the context of a working merchant vessel. Table 5-1 shows that VLCC tankers discharge ballast water at 

a rate of 5,000 m3

/hr. At this rate, one second of discharge yields 1.39 cubic meters of water. Assuming 

ETV challenge water conditions, this one second of discharge would contain 139,000 zooplankton – a 

number that would exceed the allowable discharge of organisms for the entire VLCC ballast water 

capacity by the following amounts for the proposed more stringent standards: 1.5 times greater than the 

10x D-2, 15 times greater than the 100x D-2, or 154 times greater than the 1000x D-2.

Meeting these more stringent standards will require the following technical challenges be overcome: 
52

Controls to Avoid Discharge of Untreated Water

At a minimum, ballast water piping systems must be carefully designed to avoid discharge of any 

untreated ballast water, however minimal in volume. Doing so likely would require separate uptake and 

discharge ballast water piping. Current standard practice is to use a common piping system for both 

uptake and discharge. In addition, guarding against discharges during brief interruptions in treatment 

during start-up or shut-down may require that BWMS be designed to re-circulate treated ballast water to 

confirm its treatment status before discharge. 

Controls to Avoid Cross-Contamination 

• Isolating the ballast-piping system. Many ships have a cross-over to fire mains, black and 

grey water drains, bilge water lines, and cooling water circuits. 

• Maintaining a high level of tank structure integrity. Especially in aging vessels, tank 

structures can permit transfer of fluids from adjacent tanks, piping systems running through 

tanks, fluids pooling on tank tops, and directly from ambient water through seams or pipe 

fittings in the vessel’s side shell. 

• Protecting tank vents. Ballast tanks vents are typically fitted with only a rough screen or a 

ball check device to minimize entry of seawater. Protecting these vents from ingress of 

untreated seawater will become more critical if standards become more stringent. 

In-tank Monitoring, Treatment and Mixing

Careful monitoring of in-tank conditions will be very important under the following conditions: when 

ballast water hold times are very long, thus enabling surviving organisms to reproduce, or when they are 

very short, thereby reducing time for treatment to take effect; when in-tank sediment loads provide a 

protective layer for organisms, shielding them from the disinfection process; and when highly 

heterogeneous (“patchy”) uptake ballast water overwhelms the treatment process. 

Overcoming these challenges requires developing means to:

• Monitor tank conditions, although doing so is difficult because ballast water tanks are 

typically complex and are known to have hydrodynamic “dead zones” that are not flushed 

out during a typical ballast cycle. 

• Treat (or re-treat) a full ballast water tank, such as would be needed when the ballast water 

uptake is ineffective, when it has been contaminated from external sources, or when the 

expected hold time has been exceeded. 

• Mix a full ballast water tank. An ideal mixing system would suspend sediment loads, permit 

even treatment of the tank’s entire contents, and permit representative monitoring of the tank. 
53

Improving the Efficacy of Mechanical Separation and Disinfection Technology

The performance of current “filter and disinfect” treatments is especially limited in circumstances when 

the ballast water uptake is patchy or has a high sediment load. 

5.3.2. Idealized Designs for BWMS

The water treatment industry is an obvious place to turn for developing new BWMS. This industry has 

developed methods to disinfect large volumes of water to very high standards. New approaches adapted 

from that arena may be very efficacious and able to achieve the proposed, more stringent standards, but 

it would take time to develop, test, and determine their practicality and cost impacts. Nonetheless, in 

thinking about an idealized design for ships, it is a useful thought exercise first to consider elements 

from a shore-based treatment system. 

To that end, the Panel developed a hypothetical design for an onshore ballast water treatment plant with 

a design capacity of 20,000 m3 of ballast water per day. This is equivalent to ~800 m3 per hour, roughly 

similar to a “low ballast dependent” vessel such as a containership. (“High ballast dependent” vessels, 

such as Great Lakes bulkers and large tank ships, would require a treatment plant 5 to 12 times larger.) 

The design requirements for this idealized, hypothetical treatment plant were estimated as:

• Equalization tanks of volume 20,000 m3.

• Plain sedimentation area of ~1,000 m2.

• Granular media filtration of ~120 m2.

• Three UV units each at ~800 m3 per hour.

• Sludge and backwash handling.

• Possibly to include a membrane-filtration unit. 

Based on the long history of water treatment plants, the Panel thinks it likely that such an idealized 

system could meet IMO D-2, and indeed, 1000x D-2 standards for all size fractions, including the IMOspecified bacteria. Nonetheless, pilot scale testing would be needed to confirm optimum design 

parameters. Such pilot testing programs are common practice in water treatment plant design.

Using the Idealized Design as a Basis for Conceptualizing New Shipboard BWMS

The previous section describes opportunities for incremental improvements in BWMS. Here the Panel 

illustrates the second pathway for improved BWMS – that is, the design of wholly new systems – for the 

purpose of meeting the proposed, more stringent standards. The example concept discussed below draws 

upon the operational particulars of the idealized system just described within the context of the technical 

and operational constraints for shipboard BWMS. 

A wholly new treatment design would significantly increase the operational burden on ship operators, 

but it is technically feasible to integrate wholly new treatment systems into new vessel designs. 

Integrating such an idealized system into existing vessels would be technically challenging on most, and 

not possible on many, existing vessels. Finally, such a conceptual system and processes would need 

better definition and specification in order to develop cost-benefit analyses; neither capital nor operating

costs have been estimated.
54

In order to better convey the distinction between incremental improvements to BWMS and new designs 

for BWMS, an illustrative, hypothetical concept sketch of a new design for shipboard BWMS is 

presented in Figure 5-1. This concept sketch is based on a Panamax container ship having a ballast 

volume of 17,000 m3 and a discharge rate of 500 m3

/hr. This sketch is illustrative only. It is presented 

solely to assist in the evaluation of how more stringent treatment standards might impact vessel 

arrangements, operations and costs. For example, this system would likely require at least three to four

times the number of components, space, expense, and effort compared to existing BWMS.

By way of overview, this conceptual system would be capable of achieving higher filtration levels, 

provide greater control of oxidant levels in tanks, and enable a final disinfection using UV radiation. The 

treatment process would be integrated through use of large media filters integral to the vessel hull for

ballast water uptake and discharge and through recirculation of the ballast water in the ballast water 

tanks in order to dose, monitor, and maintain oxidant levels in the ballast water tanks. For ballast water 

discharge, a residence tank would be considered adequate to ensure neutralization of the oxidant. A final 

UV disinfection step would be handled using a dedicated ballast water discharge connection. Details for 

each of these steps for this idealized system are described below. 

Figure 5-1. Concept Sketch of a New Approach to Shipboard Ballast Water Treatment (TYP means 

“typical”).

Ballast Water Uptake

Two traditional, but oversized, sea chests (intake structures for ballast water in ships’ hulls) would serve 

to take up ballast water. Piping would generally be 300 mm nominal. Each sea chest would include 

standard skin-valve isolation and piping materials. The sea chests would be located port and starboard, 

one high and one low, with a cross-over suction main connecting each. This would provide flexibility 

for avoiding sediment when the ship is close to the bottom, and algal blooms when the ship is light and 

the high sea chest is close to the surface. The Panel recognizes that sea chests can provide refuge for 

nonindigenous species, but methods for keeping them and adjacent hull areas free of fouling organisms

were not considered, as such considerations were beyond the charge. 
55

The cross-over suction main would discharge by gravity into two large media chambers plumbed in 

parallel and each sized for full flow. This arrangement would allow one to be by-passed during backflush cycles. Each would be built into a one-meter-height double bottom in the ship’s hull and 8 m

2 for a 

volume of 64 m3 each. Industrial wastewater industry media with tolerance for velocities approaching 60 

m/hr, and a useful life of six years between dry dock periods would be considered. Six-year servicing of 

media would be through manhole covers.

Ballast water leaving the media filter would be disinfected prior to entering the ballast water tanks, 

either by a UV or an oxidant chemical. This transfer would be possible by using ballast water pumps, or 

through gravity when there is adequate head pressure from the sea. The piping would be direct, through 

a pipe tunnel for ease of monitoring condition and servicing, and have no cross-connects.

In Tank

Once a ballast water tank is full or partially full, it would be periodically mixed through the use of lowpressure high-volume air bubbles, or in-tank eductors. This mixing would allow the application of an 

oxidant to a prescribed level, and the monitoring and the maintenance of that oxidant level. Mixing 

frequency would be based on detected oxidant decay levels, as well as calculations to prevent sediment 

from settling.

The tanks would be fitted with pressure-vacuum relief valves that only open when the ballast water is 

being transferred or occasionally to relieve built-up pressure or vacuum from a diurnal cycle. The 

gauging system would be a closed system to limit contaminants from entering the tanks. At least two 

tank vents would be installed. Each vent would be fitted for ready connection to ventilation blowers to 

facilitate gas-freeing tanks to make safe for personnel entry.

Depending on the required oxidant level, the ballast tanks might also require a special coating system. In 

addition, piping system gaskets and valve seals might also require special materials not typically used in 

seawater applications.

Discharge

Each tank would be fitted with piping for deballasting with a high suction at approximately 300 mm 

above the tank bottom, and a low suction at approximately 75 mm above the tank bottom. The high 

suction would be used for ballast tank discharge, such that the discharge does not contain sediment. The 

low suction would be used for stripping sediment from tanks when suitable disposal facilities are 

available.

The discharge piping would be independent from the uptake piping. Each tank would be outfitted with 

an isolation valve connecting it to the discharge main header. The header would lead to a reactor tank of 

one-meter height built into the ship’s double bottom with at least 25 m3 capacity, allowing a contact time 

of at least three minutes. During the contact time, the oxidant level would be neutralized and water 

quality confirmed prior to discharge. The system would be failsafe, returning the ballast water to the 

ballast water storage tank if needed.

A dedicated seawater overboard, designed to avoid contamination from ballast water uptake or other 

sources, would be fitted for discharging the ballast water. The disinfection step would be as close as 
56

practical to the overboard. This final disinfection step would provide assurance against contaminants in 

the reactor tank where the oxidant was neutralized, as well as providing a measure of caution in treating 

the ballast water a second time by a different process.

The ballast water could be moved through the discharge by gravity if there is adequate head in the 

ballast tank. At any time, a pump would take suction on the reactor tank, avoiding pump contact with the 

oxidants. The pump would then discharge to the UV unit and overboard.

Summary

In summary, reaching the USCG Phase-2 standard, or even 100 times the IMO D-2/ Phase 1 standard, 

will likely require wholly new treatment systems. Such new systems will have many attributes different 

from existing BWMS. They will use new technological devices, including those drawn from the water 

treatment industry; employ multistage treatment processes; emphasize technological process controls 

and multiple monitoring points to ensure desired performance, rather than rely on end-of-pipe testing; 

include physical barriers to minimize the potential for cross-contamination of the system; and become 

part of an integrated ballast water management effort. These new approaches will achieve higher 

performance, but will require time to develop, test, and determine their practicality and cost.

In addition, new BWMS technologies will need to become more energy-efficient. Driving factors 

include rising fuel costs, potential future valuations or other constraints on air emissions and other 

pollutants, and potential future taxes of carbon sources from maritime shipping. To date, attempts to 

meet proposed discharge standards generally have increased the energy required for ballast 

management. New BWMS methods should attempt to reverse this trend. Recent innovations have 

significantly reduced the volume of discharged ballast water, and in some cases eliminated discharges in 

all routine operations. Such direct approaches should continue and their reduced environmental impact 

should be recognized and encouraged in regulatory, monitoring and enforcement efforts. These 

approaches are discussed further in response to charge question 4.

5.4. Recommendations for Addressing Impediments and Constraints

Charge question 3c. What recommendations does the SAB have for addressing these impediments and 

constraints? 

Several existing technologies have demonstrated compliance with the D-2 standard during testing 

periods. However, it is not clear that these BWMS will operate consistently at this level of performance 

on board the many thousands of vessels that will require their use. Clearly defined and transparent 

programs for compliance monitoring and enforcement are needed to promote consistent, reliable 

operation of BWMS; such programs do not yet exist. Ideally, vessel crew members would have the 

technological capability to monitor BWMS efficacy, and make real-time corrections to maintain 

compliance. Further, it is important that BWMS manufacturers document and report performance 

metrics beyond discharge treatment efficacy. This information would enable vessel operators to select 

systems that best integrate with their operations. For example, the ETV protocol provides guidance for 

third-party evaluation of factors such as energy consumption and reliability. These and similar metrics 

should be encouraged. 
57

Although meeting significantly higher standards will likely require completely new treatment 

approaches, the Panel can predict neither which combination of treatment processes will achieve the 

highest efficacy nor their ultimate performance. The Panel recommends that one or more pilot projects 

be commissioned to explore new approaches to ballast water treatment, including tests of ballast water 

transfer and treatment at a reception facility 

5.5. Impediments Based on Organism Type 

Charge Question 3d. Are these impediments more significant for certain size classes or types of 

organisms (e.g., zooplankton versus viruses)? 

Shipboard impediments apply to all size classes of organisms and specified microbes. This broad 

conclusion is based on analysis of BWMS test results, as well as general considerations of the treatment 

processes and the vessel application constraints.

With regard to specific technologies, however, BWMS performance varies across target organisms. For 

example, existing BWMS are capable of removing (e.g., mechanical separation) or killing (e.g., 

deoxygenation, UV, chlorine dioxide) the great majority and in some cases, nearly all organisms ≥ 50 

μm; UV irradiation kills or inactivates unicellular organisms and viruses more efficiently than it does 

metazoans; and deoxygenation does not eliminate bacteria but rather alters microbial communities.

Such variation among organisms is exemplified by testing data. Section 4 of this report reviews results 

of seven BWMS that “reliably met” the IMO D-2 standard. All treatment systems were limited in their 

ability to reach extremely stringent, proposed standards for total bacteria. In addition, although they met 

IMO D-2 standards, some live organisms were found in either one or both of the ≥ 10 to < 50 μm and ≥

50 μm size classes. In summary, these data indicate that current technology is broadly challenged by 

bacterial counts and sometimes selectively challenged by both ≥ 10 to < 50 μm and ≥ 50 μm size 

classes.

5.6. Sterilization of Ballast Water Discharge

Charge Question 3e. Can currently available treatment processes reliably achieve sterilization (no 

living organisms or viable viruses) of ballast water onboard vessels or, at a minimum, achieve zero or 

near zero discharge for certain organism size classes or types?

It is an unrealistic and unattainable goal for current BWMS to yield ballast discharge that is “sterile”, 

i.e., “free from living organisms and viruses” (Madigan and Martinko 2006). Given the volumes of 

water requiring treatment, sterilization is not possible using current technologies; there simply is not 

enough energy on a vessel to implement steam autoclaving of its ballast water tanks and piping systems. 

With respect to “zero or near zero discharge”, however, technology exists to remove most organisms in 

the size classes ≥ 10 to < 50 μm and ≥ 50 μm. As a practical matter, the Panel notes that it is not 

possible to measure zero (sterilization) or near zero discharge—especially for microorganisms such as 

phytoplankton, bacteria, and viruses, which are especially difficult to differentiate as “live” or “dead” on 

the basis of physiological certainties. If such values cannot be measured, a BWMS cannot be controlled 

to ensure zero or near-zero discharge at the “end of pipe” for a working vessel. 
58

6. LIMITATIONS OF EXISTING STUDIES AND REPORTS

6.1. EPA’s Charge Question

This section responds to Charge Question 4: “What are the principal limitations of the available studies 

and reports on the status of ballast water treatment technology and system performance and how can 

these limitations be overcome or corrected in future assessments of the availability of technology for 

treating ballast water onboard vessels?” Bearing in mind the broader charge to "provide advice on 

technologies and systems to minimize the impacts of invasive species in vessel ballast water discharge” 

(Feb. 2010 Federal Register notice), this section addresses aspects of ballast water discharge not covered 

in the responses to earlier charge questions. Several themes emerged which the Panel discusses in the 

following sections. First, improved methods for testing and reporting are needed to ensure that high 

quality data are available with which to assess BWMS performance. Second, improved data also are 

important to the development of effective approaches to enforcement and compliance. Third, existing 

data and reports on the effectiveness of practices and technologies other than shipboard BWMS are 

inadequate because insufficient attention has been given to integrated practices and technologies that 

could reduce the risk of invasions. These include managing ballast water uptake to reduce presence of 

invasive species, reducing invasion risk through operational adjustments and changes in ship design to 

reduce or eliminate the need for ballast water, and consideration of land-based reception facilities for 

ballast water treatment. Voyage-based risk assessments could be used to integrate such practices, 

through use of applied risk management principles such as Hazard Assessment and Critical Control 

Points methods. 

6.2. Testing Shipboard Treatment Systems: Protocols, Analysis, and Reporting Practices that 

Could Be Improved

This section applies to test facilities both in the U.S. and abroad and was informed by the ETV Protocol

for land-based verification of BWMS performance (U.S. EPA 2010, hereafter the Protocol). The Panel

acknowledges the many efforts put forth by various technical panels and stakeholder groups over many 

years to draft, validate and finalize the Protocol. Most of this section focuses on land-based verification 

testing (used to gain Type Approval from Maritime Administrations) rather than shipboard verification 

testing (also used to gain Type Approval) or compliance testing (used to determine adherence to any 

discharge standard when a vessel enters a port of call). This is because, to date, programs that address 

these types of testing have not been finalized in the U.S. 

6.2.1 Confusion of Research and Development and Certification Testing

In some cases, little if any distinction is made between research and development (R&D) testing and 

verification testing. Adjustments to BWMS often are made during testing of prototypes and, in some 

cases, only the most favorable results are reported. Thus, certification may be gained on the basis of 

unrealistically favorable results that may not be representative of replicated testing with multiple 

commercially available units of a BWMS. To address this problem, the Protocol requires that BWMS 

undergoing verification testing are “prefabricated, commercial-ready treatment systems” and that all test 

results be reported (U.S. EPA 2010). Given the early state of the BWMS industry, mass-produced
59

assembly line systems are not currently tested. As indicated in the Protocol, R&D testing should be 

barred from use in certification testing.

To ensure that the performance of ballast water treatment systems is objectively and thoroughly 

evaluated during verification testing, experienced specialists in an independent testing organization 

should conduct the tests (as required in the Protocol), rather than the system manufacturers. This is 

important because research has shown that it is extremely difficult for system creators—who have 

constructively designed their systems—to change their perspective and instead view their system from 

the “deconstructive” state of mind that is focused on finding flaws and exposing weaknesses and 

limitations (Myers 1979). Thus, it is critically important that verification testing be conducted by 

independent specialists in order to assess system performance in a scientifically rigorous way. Further, 

as noted in the Protocol, the credentials of these personnel should be approved by the Verification 

Organization (the entity that oversees testing preparation, testing and the Verification Report issued by 

the test facility at the conclusion of testing). In sum, testing should be conducted by a party that is 

independent from the manufacturer and has appropriate, established credentials. 

6.2.2 Lack of Standardized Testing Protocols

Comparative evaluations of the performance of different BWMS are hampered by inconsistencies in 

discharge standards and in testing protocols. As shown in Table 2-1, there are diverse state, national and 

international discharge standards for ballast water—including differences in limits that vary by orders of 

magnitude for similar categories of organisms. This range of standards not only results in confusion for 

the regulated industry but also provides significant challenges for testing of BWMS. Performance 

standards set requirements for technology to achieve and should help to advance progress in treatment 

system designs, but only if a set of standardized, practical, scientifically rigorous assessment techniques 

is available to evaluate system performance. The IMO standards are based upon different size groups of 

organisms, and all size groupings pose challenges for assessing performance. 

Comparison of the performance of different ballast water treatment technologies requires consistent 

testing protocols regardless of the target discharge standard (Phillips 2006; Ruiz et al. 2006). To date, all 

BWMS have been evaluated using the basic approaches provided by the IMO Guidelines for Approval 

of Ballast Water Management Systems (G8) and the Procedure for Approval of Ballast Water Systems 

that Make Use of Active Substances (G9) (IMO 2008a,b). While G8 and G9 suggest a basic framework, 

the level of detail required for rigorous and comparable BWMS testing is lacking. The state of 

California also has developed ballast water treatment technology testing guidelines that are intended to 

provide a standardized approach for evaluating treatment system performance (Dobroski et al. 2009). 

Procedures also are are being developed for verifying vessel compliance with California performance 

standards.

The 2010 Protocol is a federal program that is much more detailed and proscriptive regarding test 

facility design, sampling design and volume, sample handling, analytical methods, data reporting and 

QA/QC requirements. However, this Protocol has yet to be implemented in practice or broadly adopted. 

Thus, at present there is no broad international program that includes performance standards, guidelines, 

and protocols to verify treatment technology performance, and no standardized sets of methods for 

sampling and analysis of ballast water to assess compliance. The existing federal and various state 

standards lack consistency as well. Treatment evaluations generally are designed to test whether a given 
60

technology can meet IMO D-2 standards in accordance with the IMO G8 or G9 Guidelines (IMO 2008

a, b).

With exception of BWMS installed aboard vessels enrolled in the U.S. Coast Guard’s (USCG) 

Shipboard Technology Evaluation Program (STEP), BWMS presently are not approved for use in 

compliance with proposed federal ballast water management requirements. Thus, while there are various 

state ballast water management requirements, there is no formal U.S. type approval program for BWMS

(although one is described in the USCG proposed final rule). The EPA has, however, included 

provisions in the draft NPDES Vessel General Permit for vessels with treatment systems that discharge 

ballast water containing biocides or chemical residues. 

Performance standards set requirements for technology to achieve and should help to advance progress 

in treatment system designs, but only if a set of standardized, practical, scientifically rigorous 

assessment techniques is available for use in assessments. All existing and proposed performance

standards are based upon different size groups of organisms, and all size groupings pose challenges for 

accurate assessments of treatment performance (see below). In the IMO D-2 performance standard, 

organisms in the < 10 μm size class are represented by a subset of taxa consisting of three indicator 

bacteria or bacteria groups (Vibrio cholerae, Escherichia coli, and Enterococci). Assessment has relied 

upon a subset group of organisms as representative of treatment of all bacteria (see Section 6.2.3, 

below). There is as yet no strong evidence for suitable proxy organisms to represent the virus size class, 

and no acceptable methods to verify compliance with a total virus standard (which is in the proposed 

USCG Phase 2 performance standard).

The following section provides Panel recommendations for future versions of the ETV Protocol, thus it 

focus on differences from the Protocol rather than reiterating recommendations made in the Protocol. 

Because the Protocol pertains only to land-based verification testing (not shipboard testing), the Panel’s 

recommendations focus on land-based testing for verifying treatment performance by independent 

testing operations. This section also comments on shipboard testing. 

Test Verification Factors

The Protocol recommends that all treatment systems be verified using the following factors: biological 

treatment efficacy (or BE, defined as the removal, inactivation or death of organisms), operation and 

maintenance (O&M), reliability as measured by the mean time between failures (MTBF), and 

environmental acceptability including residual toxicity and safety. The Panel agrees with the Protocol

that biological treatment efficacy should be measured as the concentration, in the treated ballast water 

discharge, of the organism size classes indicated in the IMO D-2 and USCG Phase 1 performance 

standards, with a minimum concentration of organisms in the control tank discharge. Other 

measurements can include water quality parameters in comparison to appropriate water quality 

standards. Verification protocols should include detailed descriptions of on-site sampling, sample 

handling (chain of custody), QA/QC, in-place mechanisms for selecting independent laboratories with 

appropriate expertise and certification to conduct the sample analyses, and requirements for compliance 

reporting. 

The Panel also agrees with the Protocol that tests and species selected for toxicity testing during 

commissioning need to have carefully justified protocols detailed in the Test Plan. BWMS that involve a 

chemical mode of action are regulated under the National Pollutant Discharge Elimination System 
61

(NPDES) permit process (Albert et al. 2010), which requires demonstration of “no adverse effects” as 

evaluated through chemical-specific parameters and standardized Whole Effluent Toxicity (WET) 

testing (U.S. EPA 2002a-c; 40 CFR 136.3, Table 1A). WET experiments are designed to assess the 

effects of any residual toxicity on beneficial organisms in receiving waters. Standardized acute and 

chronic toxicity assays have been developed by the EPA for a limited number of freshwater and marine 

species (Table 6-1). The Protocol does not include specific freshwater assays, but recommends that 

toxicity tests for biocide treatments in brackish and marine waters should be selected from the EPA 

acute toxicity assay for mysids (EPA OPPTS Method 850.1035; 

http://www.epa.gov/opptsfrs/OPPTS_Harmonized/850_Ecological_Effects_Test_Guidelines/Drafts/850-

1035.pdf ), and the chronic toxicity assays for the inland silverside Menidia beryllina (larval survival 

and growth, EPA Method 1006.0; http://www.epa.gov /OST/WET/disk1/ ctm13.pdf) and the sea urchin, 

Arbacia punctulata (fertilization, EPA Method 1008.0; http://www.epa.gov/OST/WET/disk1/ctm15.pdf

). The Panel recommends that freshwater assays also be included in toxicity testing. 

The Protocol also recommends that complete results of verification testing, including equipment

failures, be reported as standard practice. These data are needed to enable realistic evaluation of a given 

BWMS. At present, there is no requirement under the IMO G8 guidelines to report tests in which a 

BWMS does not perform to the D-2 performance standard. The Panel strongly recommends that reports 

should include all test results, and that criteria for approval should consider the failure rate (proportion 

of tests that were successful).

Table 6-1. Freshwater and marine species for which the U.S. EPA has developed standardized acute

and chronic toxicity assays (http://www.epa.gov/waterscience/WET).

_________________________________________________________________________________________

Habitat Acute Toxicity Chronic Toxicity 

_________________________________________________________________________________________

Freshwater

Algae --- Selenastrum capricornutum (growth) 

Zooplankton Ceriodaphnia dubia Survival, reproduction

Daphnia magna ---

Daphnia puplex ---

Fish Bannerfin shiner (Cyprinellale edsi) ---

Brook trout (Salvelinus fontinalis) ---

Fathead minnow (Pimephale spromelas) Larval survival, growth; embryo-larval 

survival, teratogenicity

Rainbow trout (Oncorhynchus mykiss) ---

Marine

Mysid shrimp Americamysis bahia Survival, growth, fecundity

Sea urchin --- Arbacia punctulata - fertilization

Fish Sheepshead minnow (Cyprinodon Larval survival, growth; embryo-larval

variegatus) survival, teratogenicity

Silversides (Menidia beryllina, M. M. beryllina - larval survival, growth

menidia, M. peninsulae)

_________________________________________________________________________________________
62

Challenge Conditions

The Panel recommends that testing should be applied across the gradient of environmental conditions 

(temperatures, salinities) represented by the Earth’s ports; to address this concern, the ETV Protocol 

requires testing at a minimum of two salinities (U.S. EPA 2010), although some Panel members argued 

the minimum should be three. All treatment technologies should function well across the range of 

physical/chemical conditions and densities/types of biological organisms that a ship encounters. Thus, 

BWMS ideally should be verified using a set of standard challenge conditions that encompass the suite 

of water quality conditions, and that capture environmental conditions represented by ports and a range 

of densities of the organisms and organism size classes (unless a BWMS is designed, and certified, for 

only a specific subset of conditions). 

The ETV Protocol states that the objectives for challenge conditions are to verify treatment system 

performance using a set of “challenging, but not rare, water quality conditions representative of the 

natural environment,” and to verify removal or kill of organisms ranging in size from bacteria to 

zooplankton, using natural assemblages and appropriate analytical techniques that enable quantification 

of densities of live organisms (U.S. EPA 2010, p.18). It is important to evaluate the effectiveness of 

treatment systems under conditions that challenge the technology because certain water quality 

conditions can interfere with some treatment processes. These physical/chemical environmental 

conditions are generally understood and relatively few in number, which helps to limit the number of 

water quality metrics that must be included in the protocol (Table 6-2). 
63

Table 6-2. Comparison of the ETV Protocol’s recommendations (U.S. EPA 2010) and the alternatives the Panel recommends that EPA consider, 

with respect to minimum criteria for challenge water total living populations, criteria for a valid biological efficiency (BE) test cycle at land-based 

facilities (living organisms in control tank discharge after a holding time of at least 1 day), and water types (salinity groupings) for completion of BE 

tests.1

 Three salinity ranges are recommended for BWMS that are planned for use in freshwater, brackish, and marine waters.

_ _____________________________________________________________________________________________________

Minimum Criteria for Challenge Water Total Living Populations; and

Criteria for a Valid BE Test Cycle - Living Organisms in Control Tank Discharge After 1 Day Holding Time

Size Category2 ETV Protocol . Panel Alternatives

> 50 μm 105 organisms m-3, 5 species in 3 phyla same

> 10 μm and < 50 μm 103 organisms mL-1, 5 species in 3 phyla same

Other3 < 10 μm: 103 mL-1 as culturable < 10 μm: 103 selected protists mL-1

aerobic heterotrophic bacteria < 2 μm: same as ETV for < 10 μm

Water Types (Salinity Groupings) for Completion of BE Tests3

 Fresh (salinity < 1) Two salinity ranges; Two or three salinity ranges; 

 Brackish brackish ≡ salinity 10-20; brackish ≡ salinity 1 to < 28

 Marine marine ≡ salinity 28-36 marine ≡ salinity > 28

Physical/Chemical4

 Environmental: Temperature (4-35o

C), DOC, POC, TSS, MM, pH, DO

 Others of Specific Interest: Example - nutrient concentrations (TN, TP, TKN, NHx, NOx, SRP)

_ ____________________________________________________________________________________________________

1 Abbreviations: DOC, dissolved organic carbon; POC, particulate organic carbon; TSS, total suspended solids = particulate organic

 matter (POM) + MM (mineral matter); DO, dissolved oxygen; TN, total nitrogen; TP, total phosphorus; TKN, total Kjeldahl nitrogen;

NHx, ammonia + ammonium; NOx, nitrate + nitrite; SRP, soluble reactive phosphorus.

2 Size ≡ maximum dimension on the smallest axis.

3 Effects on culturable aerobic heterotrophic bacteria are assumed to be indicative of effects on all bacteria.

4 The ETV Protocol’s water quality challenge matrix for verification testing includes the following minimum water characteristics for the three

 salinity water types as: Dissolved organic matter, 6 mg L-1 as DOC, and particulate organic matter, 4 mg L-1

 as POC; MM 20 mg L-1 and TSS 24 mg L-1

; and temperature range 4-35oC.
64

In recognition of the difficulties that can be encountered, especially in ship-based testing, tests of the 

three salinity ranges could include two land-based tests and one ship-based test. A rationale for 

recommending tests of all three salinity ranges is that if a given BWMS is planned for use across all 

three salinity ranges, but testing indicates that its efficiency at organism removal is poor under one or 

more of the salinity groupings, then that system should not be used by ships visiting ports that are 

characterized by such conditions. Similarly, if a BWMS is planned for use across other environmental 

gradients (e.g., temperatures from cold to warm waters, or salinities from fresh to marine), but tests 

indicate that it has poor efficiency in removing biota under part of the natural range, then that system 

should not be used by ships visiting ports that have such conditions. Indeed, the USCG proposed rule 

indicates that “at least 2 sets of test cycles should be conducted with different salinity ranges and 

associated dissolved and particulate content as described. BWMS not tested for each of the 3 salinity 

ranges and water conditions listed in this section may be subject to operational restrictions within a 

certificate of approval” (USCG 2009, p. 44666). A fully crossed design should be used where possible, 

for example, if natural water can be obtained at the desired salinity range. As another example, cold 

water testing may be critical to understand the breakdown of chemical treatments (i.e., active 

substances), but testing with natural water in the winter would encounter relatively few organisms in the 

challenge water, making it difficult to achieve recommended challenge conditions.

There are other major practical constraints on such tests. First, alterations to establish the natural range 

of physical and chemical conditions should be imposed without affecting the concentrations, diversity 

and viability of the biota present. For that reason, natural water sources ideally should be used to impose 

the levels of salinity, rather than artificially modified salinity. Artifactual interactions may occur 

between biota and artificial media (e.g., artificial seawater prepared with commercially available “sea 

salts”). The Panel thus diverges from Anderson et al. (2008) in recommending that a source of filtered, 

high-quality natural freshwater or seawater should be used to prepare treatments insofar as possible. 

There are pros and cons with either approach: Artificial sea salts are expensive but enable routine 

preparation of media. However, caution is warranted in using artificial sea salts because some 

ingredients that are not found in natural seawater, such as phthalate esters (e.g., di(2-

ethylhexyl)phthalate, a commonly used plasticizer in Instant Ocean aquarium salts), are abundant and 

can be toxic to aquatic life, resulting in spurious data (e.g., Peal 1975; Moeller et al. 2001). 

In addition, various dissolved organic compounds that are important to the nutrition and the life histories 

of aquatic organisms likely will be missing from artificially constructed media. While use of natural 

waters avoids such problems, the natural water source should be as free as possible from toxic 

pollutants, which are increasingly ubiquitous in fresh, brackish, and coastal marine waters (Kay 1985;

Pate et al. 1992; Loganathan and Kannan 1994; Hoff et al. 1996; U.S. EPA 2000; Shaw and 

Kurunthachalam 2009), or contain at most only trace levels of such pollutants. Final selection of natural 

versus an artificial water sources requires careful consideration of these issues. In addition, when using 

artificial water sources or otherwise modifying environmental conditions, timing is important; care 

should be taken to avoid imposing rapid environmental changes that, alone, could stress or kill the biota 

tested.

Similarly, the Protocol recommends adjusting particulate organic matter (POM), if natural waters do not 

meet challenge conditions, by adding commercially available humic materials, plankton, detritus, or 

ground seaweed; commercially available clays can be added to adjust the mineral matter concentration 

(U.S. EPA 2010). However, the Panel is concerned that the cation exchange capacity of the dried, then 

rehydrated, clays can significantly alter plankton communities (Avnimelech et al. 1982; Burkholder 
65

1992; Cuker and Hudson 1992). Artificial modification of dissolved organic carbon (DOC) is difficult to 

achieve without a strong potential of affecting the biota present, especially the smaller size-fraction 

components. The Panel believes that the testing organization should be required to verify, insofar as 

possible, that in preparing the test water, any materials added had minimal effects on the biota, and 

“minimal effects” should be clearly defined. 

The IMO (2008a, b), the Protocol, and other suggested standards (e.g., California VGP 401 

certification/State regulations; see Albert et al. 2010) make no mention of protists in the < 10 μm size 

range. Many harmful organisms occur in this size range (e.g., harmful “brown tide” pelagophytes 

Aureococcus anophagefferens and Aureoumbra lagunensis, many harmful cyanobacteria, and certain 

potentially toxic dinoflagellates; see Burkholder 1998, 2009). The selected bacteria presently targeted 

for standards are not useful as indicators for these taxa which, as a general grouping, can adversely 

affect both environmental and human health (Burkholder 1998, 2009). Thus, failure to consider this size 

class represents a serious omission in efforts to protect U.S. estuaries, marine waters and the Great 

Lakes from harmful species introductions. For some of these taxa, such as toxigenic Microcystis spp. 

affecting some of the Great Lakes (e.g., Boyer 2007), the tendency of the cells to aggregate into colonies 

can sometimes “boost” them into the > 10 μm size range during filtration processes, but the size 

measurements are based on individual cells.

There is a critical need to consider harmful representative protists (which should be expected to vary 

depending on the geographic region) from this size class in developing protective ballast water 

standards. Depending on the salinity and the region, and based on the smallest cell dimension, examples 

of candidates could include selected toxigenic cyanobacteria such as Anabaena flos-aquae, the 

haptophyte Prymnesium parvum, brown tide organisms Aureococcus anaphogefferens or Aureoumbra 

lagunensis, small toxigenic dinoflagellates such as Karlodinium veneficum, and the pathogenic 

protozoans Giardia spp. and Cryptosporidium parvum that are found across the salinity gradient. 

Accordingly, protists in this size class should be included in standards for assessing the performance of 

BWMS in land-based testing if they were naturally occurring at the test facility. For shipboard 

verification testing or compliance testing, where the source water is unknown until sampling occurs, 

appropriate organisms for evaluation can be selected accordingly.

Verification Testing

The Panel offers considerations that differ from the Protocol on some points, including specifics for 

collecting water quality and biological samples for verification testing of BWMS (Table 6-3). Some 

panel members argue that these points should be a part of verification testing; others argue that such 

approaches could be incorporated into future revisions of the Protocol if their utility, effectiveness, and 

practicability were deemed appropriate. Some Panel members have concerns that such analyses would 

(1) provide qualitative indications of viability, not the quantitative data on the density of organisms 

necessary to assess BWMS performance in accordance with a discharge standard, or (2) overestimate 

the number of viable organisms. Also, conducting new analyses, in addition to those required in the 

Protocol, might not be practicable by already busy testing teams. 

For zooplankton, phytoplankton and other protists, the Panel supports the need for collecting at least 3-6 

m3 of sample volume at each required location on a time-averaged basis over the testing period. Field 

quality control samples and field blanks should be taken under actual field conditions to provide 

information on the potential for bias from problems with sample collection, processing, shipping and 
66

analysis (Ruiz et al. 2006). Accepted scientific methods should be used for all analyses (e.g., for water 

quality parameters, U.S. EPA 1993, 1997; American Public Health Association (APHA) et al. 2008). 

Biological samples should be collected in a time-integrated manner during the tests, and sample 

collection tanks should be thoroughly mixed prior to sampling to ensure homogeneity (U.S. EPA 2010). 

Samples collected from control and treated tank discharges should be taken upstream from pumps or 

other apparatus that could cause mortality or other alterations, and if pumps and valves must be used 

upstream of sample collection, they should previously have been tested and shown not to damage 

organisms (U.S. EPA 2010). Note that analysis of some parameters is extremely time-sensitive (Table 6-

3). For example, zooplankton die-off occurs in some samples held for 6 hours or more (U.S. EPA 2010); 

the timing of die-off likely varies depending on the zooplankton community, and the upper limit should 

be determined at each test facility. The approximate maximum hold times should maintain detectable 

zooplankton mortality over time at < 5%. 
67

Table 6-3. Sample volumes, containers, and processing for core parameters and auxiliary nutrients (nitrogen, N;

phosphorus, P; silicate, Si; carbon, C). Note that HDPE ≡ high-density polyethylene, and POC information is from

Baldino (1995). Recommendations that differ from those in the ETV (U.S. EPA 2010) are indicated in bold.

1

___________________________________________________________________________________________________________

Parameter Minimum Sample Containers Processing/Preservation Maximum

Volume Holding Time

___________________________________________________________________________________________________________

TSS 100 mL HDPE or glass Process immediately or 1 week

store at 4o

C

DOC 25 mL glass Pre-combusted GF/F filters; 28 days

preserve filtrate with H3PO4

(pH < 2), hold at 4o in darkness

(APHA et al. 2008)

POC 500 mL HDPE Filter (GF/F in foil); freeze filter 28 days

until analysis

MM = TSS - POC ---- ---- ----

DO 300 mL glass BOD Fix (Oudot et al. 1988); titrate in 24 hours

or bottles 2-24 hours; or

in situ sensor Continuously recording

Chlorophyll a,

1 400 mL dark HDPE Filter (GF/F); fix with saturated 3 weeks

pheopigments MgCO3 solution; freeze filter until

analysis

Phytoplankton No.2 500 mL dark HDPE Filter (Nuclepore or Anotech); process

(viable, < 10 μm - assess autofluorescence (e.g. immediately

selected harmful taxa) MacIsaac and Stockner 1993), or

Filter, fix (e.g. 0.2% (v/v) 3-4 weeks

formalin), freeze filter; or

filter, fix, followed by selected months

molecular techniques (e.g. 

Karlson et al. 2010)

___________________________________________________________________________________________________________
68

Table 6-3 (cont.)

_____________________________________________________________________________________________________________

Parameter Minimum Sample Containers Processing/Preservation Maximum

Volume Holding Time

_____________________________________________________________________________________________________________

Phytoplankton No. 3 m3 (1,000 L) 60 mL Viable: No preservative; stain process

(viable, nano-/ → 1 L dark HDPE with FDA, CMFDA; or, immediately; or

micro-plankton, fix with acidic Lugol’s solution 28 days,

> 10 to 50 μm and (Vollenweider 1974), store at preferably

> 50 μm) 3 4oC in darkness, and quantify 1 week 

as viable when collected 

and

combine with various molecular

techniques to confirm harmful

taxa of interest (e.g. Karlson et 

al. 2010)

Other protists (#) 1 500 mL 100 mL, Techniques appropriate for the variable

(viable heterotrophs, dark HDPE selected taxa (e.g. U.S. EPA 

< 10 μm - selected 2005)

harmful taxa) 

Zooplankton # 3 m3 (3,000 L) 4 1-L flask No preservative; subsample Process

(viable, > 50 μm) → 1 L 450 1-mL wells3 and probe; immediately

fix with buffered formalin and (< 6 hr) 5

Rose Bengal’s solution to 

quantify; or

Zooplankton # fix as above and quantify as Process within

(viable) (cont’d.) formerly viable (Johnson and 1 month

Allen 2005)

Bacteria > 1000 mL sterile HDPE Plate on appropriate media Process

(active culturable, (U.S. EPA 2010)6 Immediately

aerobic heterotrophic -

selected taxa)

Nutrients1 -

 TN, TP total 60 mL varies Varies – see standard methods varies (mostly 

 Kjeldahl N (TKN) (U.S. EPA 1993, 1997; APHA et 28 days)

al. 2008; and U.S. EPA 2010, p.39)

___________________________________________________________________________________________________________
69

Table 6-3 (cont.)

_____________________________________________________________________________________________________________

Parameter Minimum Sample Containers Processing/Preservation Maximum

Volume Holding Time

_____________________________________________________________________________________________________________

NOxN, NHxN, SRP, 60 mL varies Varies – see standard methods varies (mostly

SiO2 as above 28 days)

______________________________________________________________________________________________________________

1 Methods in the ETV Protocol that differ from those and recommended above by the Panel for consideration are as follows: DOC – pass sample through a GF/F filter and freeze 

filtrate until analysis; chlorophyll a and pheopigments – listed as an auxiliary parameter rather than a core parameter; protists (phytoplankton, protozoans) in the < 10 μm size class 

are not considered; TN, TP, total Kjeldahl N, and silica are not addressed; and dissolved inorganic phosphate is referred to here as soluble reactive phosphorus (SRP). 

 In situ sensors are available for measuring chlorophyll a as relative fluorescence units, but not as chlorophyll a concentrations. Chlorophyll a may be considered as a core parameter 

or as an auxiliary parameter, used as a collective indicator for algal biomass. The Panel also recommends assessment of nutrients (TN, TP, total Kjeldahl N, and silica) if possible, 

although nutrients are not considered as core parameters by the ETV and the Panel recognizes that core parameters should have top priority. 

 The Panel also recognizes the fact that present performance standards are for living (viable) organisms. Because of widely acknowledged practical limitations in techniques to assess 

living (viable) organisms, in this table and explained in the writing below, the Panel suggests alternate techniques for quantifying the organisms that were viable in samples when 

collected.

2 This size category has not been considered for ballast water treatment standards by IMO (2008a,b), the ETV (U.S. EPA 2010), etc. Because many harmful organisms occur in the < 

10 μm grouping, this size class should be considered for inclusion in assessment of BWMS.

3 FDA, fluorescein diacetate; CMFDA, 5-chloromethylfluorescein. Delicate protists (e.g. wall-less flagellates) mostly would not be expected to survive the process of rapid 

concentration of large-volume samples. The Panel recognizes that samples collected for protists are not concentrated in the same way as samples collected for the larger size class: For 

the P-1 standard, 3-6 L (taken as whole water, isokinetically from the discharge of control or treatment tanks) are concentrated to 1 L, which can be done with a sieve. Nevertheless, 

this process can lyse delicate protists. As a more practical alternative than attempting to quantify viable algae and other protists from unpreserved samples, an option is to preserve

samples immediately upon collection and then assessing intact organisms as “viable when collected,” based on the fact that protists such as most algae in this general size class are 

known to lyse and/or decompose rapidly (minutes to several hours) after death, so that the cell contents become distorted or are lost even if the cell coverings remain (Wetzel 2001). It 

should be noted that vital (or mortal) stains address the question, “Is this alga living?” in a way that is substantially different than the presence/absence of intact chloroplasts and other 

cell contents. Thus, the two methods sometimes do not yield the same quantitative answer and require careful calibration.

4

 It should be noted that phototrophic organisms in this size class should be quantified using the protocols for phytoplankton, above.

5 Zooplankton die-off occurs in samples held for 6 hours or more (Naval Research Laboratory, unpubl. data; U.S. EPA 2010).

6 Media suggested by the U.S. ETV (2010, p.47) for brackish/marine taxa include 2216 Marine Agar and salt-modified R2A agar; media for freshwater species may include Plate 

Count Agar and Nutrient broth (plus agar (15 g L-1

). 
70

An alternative to quantifying viable organisms from unpreserved samples is preserving samples 

immediately upon collection and then assessing intact organisms as “viable when collected.” Some 

Panel members recommend this as a more practical alternative, whereas others note vigorous validation 

is needed before it can be recommended. This approach is commonly used in characterizations of 

microflora and microfauna assemblages in the peer-reviewed literature, based on the fact that protists 

and zooplankton deteriorate quickly once dead (within minutes to hours: Wetzel 2001; Johnson and 

Allen 2005; and see Section 6.2.3). Effective “fast-kill” preservatives can be used that cause death 

before distortion or cell lysis can occur. Standardized, accepted techniques are available for quantifying

“viable when collected” protists and zooplankton from preserved material (e.g., Lund et al. 1958; Wetzel 

and Likens 2000; Johnson and Allen 2005; and see Section 6.2.3). A shortcoming of this approach is 

that dying organisms which still contain apparently intact cellular contents would be included in the 

“viable” estimate. Thus, the number of viable organisms would be overestimated if a large fraction of 

the sample was dead. In addition, as for counts based on unpreserved material, it is difficult to assess 

whether some resistant structures such as thick, opaque cysts contain organisms with intact cell contents. 

Because of practical and environmental health/safety constraints, neither approach avoids the problem of 

likely major losses of viable organisms that occur during rapid concentration of large sample volumes. If 

a “formerly viable” approach were used, the Panel recognizes that it would need to be validated and 

approved by the Verification Organization.

6.2.3. Compromises Necessary Because of Practical Constraints in Sampling and Available 

Methods

Ideally, the goal of standard challenge conditions would include the full range of (a) challenging 

conditions present in the world’s ports, (b) organism density, (c) taxonomic diversity, and (d) organism 

size classes. Meeting this ideal goal is impeded by several serious practical constraints in sampling large 

ballast tanks effectively, and in the methods that presently are available for quantifying viable 

organisms. As Lee et al. (2010, p.19) pointed out, “perfect compliance and no failure is practically, if 

not theoretically, impossible, particularly for microbiological organisms unless ballast water is 

discharged into a land-based treatment facility or ships are redesigned to eliminate the need to discharge 

ballast water.” This section considers how the ideal can be modified to accommodate practical 

considerations while accomplishing a meaningful evaluation of the efficacy of BWMS.

Standardization of Choices of Standard Test Organisms 

The Protocol defines standard test organisms (STOs) as “organisms of known types and abundance that 

have been previously evaluated for their level of resistance to physical and/or chemical stressors 

representing ballast water technology” that are used in bench-scale testing (U.S. EPA 2010, p. 74). The 

Protocol (U.S. EPA 2010) requires that prior to full-scale verification testing, laboratory experiments be 

conducted to evaluate post-treatment viability of STO taxa used to assess the biological effectiveness of 

BWMS in removing zooplankton, protists (heterotrophic and phototrophic), and bacteria. 

The selection and development of STOs that are broadly resistant to treatments for use in testing BWMS 

performance is a fertile field of research because of the practical need (Hunt et al. 2005; Anderson et al. 

2008; U.S. EPA 2010). The Panel urges caution in the use of STOs, however, since results from a very 

small number of taxa are broadly applied to all of the organisms in the same general grouping (e.g.,

protozoans in a certain size class). An assumption that first must be validated is that the selected taxa are 

among the most resistant to treatment, so that most organisms are eliminated when the surrogate taxa are 
71

eliminated (Ruiz et al. 2006). The fundamental challenge is to identify the best species that are 

“representative” of a broad range of organisms within a given size class. Good candidates are considered 

to be easily and economically cultured in large numbers for future full-scale testing in experimental 

ballast water tanks; tolerant of a wide range of environmental conditions; reliable and consistent in their 

response to treatment across culture batches; and resilient in withstanding ballast water tests and 

sampling (Ruiz et al. 2006; Anderson et al. 2008). A list of suggested STOs is provided in the ETV 

Protocol. An obvious risk is spurious results from surrogate taxa that poorly represent the larger group 

of organisms in a given size class. Because testing with STOs is part of a larger testing process (landbased and shipboard verification testing) that employs a range of organisms, this risk is somewhat 

ameliorated. 

Protocols for STOs should include clear justification for use of these taxa under a defined set of 

conditions; careful consideration of potential confounding interactions between the STOs and natural 

species; and the percentage ratio of challenge organisms that are STOs versus naturally occurring taxa in 

the challenge water. Selection of a specific combination of STOs should be based upon extensive testing 

at bench and mesocosm scales, preferably by several laboratories located in different geographic 

regions, of a wide range of STO species, life histories, habitats, and source regions across environmental 

gradients (Ruiz et al. 2006). Consistent use of the same protocols is needed in order to minimize 

confounding factors and strengthen comparability. Ideally, several STOs or taxonomic subgroups, 

including several life stages, should be included in the tests since confidence in interpretations can be 

strengthened by this redundancy. It would also be best to include multiple strains (populations) of 

candidate STOs if possible, to account for significant intraspecific variability in response to 

environmental conditions that is commonly documented, particularly among protists (Ruiz et al. 2006;

Burkholder and Gilbert 2006). Nevertheless, the Panel recognizes that practical and economic 

considerations may prevent testing beyond use of one or two STOs to represent each size class. 

Standardization of Choices of Indirect Metrics (Surrogate Parameters)

There are practical and logistical limitations involved in obtaining statistically meaningful estimates of 

concentrations of specific organisms per unit volume in compliance testing, as required by the IMO or 

proposed by the USCG. Given these limitations, the Panel recommends adding to future compliance 

protocols parameters that are much more rapidly and easily assessed. Examples of candidate “surrogate 

parameters” are shown in Table 6-4. They can be calibrated with organism numbers in laboratory tests 

on microcosm “ecosystems,” but would be much more difficult, if not impractical, to calibrate for use 

with unknown types and numbers of organisms in ballast tanks. Therefore, surrogate parameters could 

be useful as bulk measurements in compliance testing. These parameters also could be used to augment 

existing measurements in land-based and shipboard verification testing. It will be critical to carefully 

calibrate all potential surrogate parameters with natural populations of ballast water flora and fauna 

before they can be used to evaluate the performance of BWMS – especially at the resolution of very low 

organism densities.

Increased Use of Tests at Multiple Spatial Scales

Instead of relying solely on full ship-scale testing, for practical reasons the Panel recommends that 

testing be conducted at a combination of scales as needed to address particular issues. Such tests would 

be done by the vendor of the BWMS prior to validation testing. For example, full-scale tests can pose 
72

Table 6-4. Examples of candidate “surrogate” parameters for quantifying viable organisms in ballast water, and an analysis

of their utility considering methods that are presently available.*

__________________________________________________________________________________________________________

Parameter(s) Description Suitability, Considering Methods Presently Available

__________________________________________________________________________________________________________

Chlorophyll a (chla) “Universal” plant pigment, Pros: Allows rapid processing of large numbers of samples;

found in all phototrophic algae1; standardized methods widely available2-5.

widely used as an indicator of Cons: Cannot discern cell numbers per unit sample volume; 

total algal biomass2,3 not sensitive enough to detect < 10 cells ml-1 of small algae6;

cellular chla content highly variable (0.1-9.7% fresh weight)

depending on the species7 and the light conditions8,9; methods, 

and results depending on the method, vary widely10-12.

Present status: Available methods do not allow reliable 

calibration with algal cell numbers in natural samples; improved 

methods are needed.

“Signature” or marker Diagnostic for cyanobacteria Pros: Potentially superior to chla as algal biomass indicators;

pigments (zeaxanthin) and major eukaryotic more specificity to algal groups (divisions or classes);

algal groups (e.g. diatoms, other standardized methods available13-16. 

heterokontophytes - fucoxanthin; Cons: Techniques must be applied carefully to avoid

dinoflagellates - peridinin; chloro- artifacts and sample bias17; low taxonomic resolution (can

phytes and euglenophytes - chl b)

3,13 sometimes be improved by screening samples using

microscopy18 to identify abundant taxa5

).

Present status: Available methods do not allow reliable 

calibration with algal cell numbers in natural samples; 

improved methods are needed

Adenylates, especially Indicator of total microbial biomass Pros: ~All microbial taxa have a ~constant ratio of ATP to total

ATP (adenosine in plankton, sediments17 cell carbon18; easily extracted from microbial assemblages; not 

triphosphate), and associated with dead cells or detritus19,20.

Total adenylates Cons: Cell ATP content varies for cells under environ-

(ATP + ADP, adenosine mental stress21,22; encysted cells with low metabolic 

di-phosphate, + AMP, activity have low ATP content (difficult to detect);

adenosine mono- total adenylates considered a better indicator of microbial

phosphate) biomass than ATP17 within a given size class, but

 extrapolation from small sample volumes would lead to

large error factors in estimating organism numbers.

Present status: Available methods do not enable accurate

assessment of small numbers of viable organisms per 

unit volume in stressed conditions within ballast tanks; 

improved methods are needed.

____________________________________________________________________________________________________________
73

Table 6-4 (cont.) 

__________________________________________________________________________________________________________

Parameter(s) Description Suitability, Considering Methods Presently Available

__________________________________________________________________________________________________________

INT (2-p-iodophenyl)- Commonly used tetrazolium Pros: INT accepts electrons from dehydrogenase enzymes

 3-(p-nitrophenyl)-5- salt used to measure microbial and is reduced to a reddish colored formazan (INTF) - can

 phenyltetrazolium activity (electron transport chain be quantified by simple colorimetric analysis after a very 

 chloride activity indicating viable organisms) short incubation time26; total cell numbers are quantified

in surface waters, biofilms, and under epifluorescence microscopy using a counter-stain (e.g.

sediments (freshwater to marine)23-25 acridine orange27) - proportion of population that is

metabolically active is then estimated; very sensitive method 

even at low microbial biomass and low temperatures27, with

resolution at the level of individual cells28.

Cons: Can miss cells with very low respiration (e.g. cysts), or

cells that do not use INT as an electron acceptor28; still requires

microscopy (tedious, time-consuming).

Present status: Shows promise for use with various size classes

of microorganisms in ballast water.

RNA, DNA Quantitative PCR and related Pros: Reliable quantification of targeted taxa from environtechniques; molecular and mental water samples if PCR inhibitors can be removed and 

genomic probes29-31 molecular material can be efficiently recovered29,30.

Cons: More research is needed to test the degree to which these 

can reliably discern between viable and non-viable cells,

or infective and non-infective cells, or toxic and nontoxic

cells, unless supplemented by other techniques31-34.

Present Status: Available methods do not allow reliable 

calibration with living algal cell numbers in natural samples;

quantitative methods are emerging35,36.

__________________________________________________________________________________________________________

* References used: 1 Graham et al. (2009); 2,3,4,5 Wetzel (2001), Jeffrey et al. (1997), US EPA (1997), Sarmento and Descy (2008);

 6 MERC (2009c); 7 Boyer et al. (2009); 8,9 U.S. EPA (2003), Buchanan et al. (2005); 10-12 Bowles et al. (1985), Hendrey et al. 

 (1987), Porra (1991); 13 Schlüter et al. (2006); 14,15,16 Mackey et al. (1996), Jeffrey and Vest (1997), Schmid et al. (1998), Schlüter

 et al. (2006); 17 Sandrin et al. (2009); 18 Karl (1980); 19,20 Holm-Hansen (1973), Takano (1983); 21,22 Inubushi et al. (1989), Rosaker 

 and Kleft (1990); 23-25 Songster-Alpin and Klotz (1995), Posch et al. (1997), Blenkinsopp and Lock (1998); 26 Mosher et al. (2003);

 27 Sandrin et al. (2009); 28 Posch et al. (1997); 29Caron et al. (2004); 30Kudela et al. (2010); 31Karlson et al. (2010); 32Guy et al. 

 (2003), 33Audemard et al. (2004), 34Burkholder et al. (2005), 35Jones et al (2008), 36Bott et al. (2010). 
74

extreme practical and logistical limitations and/or high risk in efforts to assess the effectiveness of 

treatment systems in removing maximal densities of harmful organisms, or mixes of representative 

organisms within certain density ranges. These risks support the use of sized-down mesocosm 

treatments (hundreds to thousands of liters; Ruiz et al. 2006; MERC 2009a-c) that are larger and 

therefore more realistic than bench-scale microcosms, but more manageable in volume than ballast 

tanks. 

Sized-down treatments help to reduce risks to human health safety and receiving aquatic ecosystems for 

testing treatment system effectiveness at removing toxic substances and residues that are part of the 

treatment process. As Ruiz et al. (2006, p.10) stated:

Economy of small scale and ease of manipulating environmental variables and community assemblage at 

the laboratory and intermediate scales make it possible and practical to estimate if a ballast water 

treatment process and system is likely to be effective over the full range of physical [chemical,] and 

biological conditions expected in the field;...the same regime on a ship would prove logistically and 

financially very unwieldy. Thus, smaller scale tests demonstrate the treatment’s performance and capacity 

across a wide range of relevant state variables.... 

This approach also allows more precise, controlled sampling during test trials (MERC 2009b). At larger 

scales, practical limitations restrict the number of conditions that can reasonably be tested, and testing is 

directed more toward ensuring functionality of the engineered system rather than understanding the 

treatment process under various conditions.

Small-scale (benchtop or laboratory) experiments minimize logistics and expense, and they can provide 

proof of concept in assessing whether a given treatment meets expectations (Ruiz et al. 2006). For 

example, if a BWMS is planned for use across the salinity gradient, then its efficacy should be tested 

across all three salinity ranges (Table 6-2). Logistically, however, it may be feasible to test two salinity 

ranges at full scale, but not the third. In such cases, small-scale and intermediate-scale (see below) tests 

could be completed using the third salinity range. Likewise, the Panel recommends that bench-top and 

mesocosm experiments complement full-scale testing.

Practical Limitations of Challenge Water Conditions

While it is important to evaluate BWMS under diverse and challenging biological, physical and 

chemical conditions to understand system performance and the broad applicability and reliability of 

BWMS, all biological and chemical challenge conditions may not be achievable during a series of tests 

using natural waters. As described above, artificial manipulations of biological, physical and chemical 

conditions may introduce significant artifacts. Therefore, without rigorous validation that a modification 

to challenge water is representative of natural conditions and does not cause artifacts (e.g., stressing or 

killing organisms), only natural ambient conditions should be used. The following options are available 

to address the difficulty in meeting challenge conditions using un-augmented challenge water: 

• Make the challenge conditions somewhat less stringent by allowing challenge water conditions 

in some replicate trials during testing of a given BWMS to fall outside of target values. For 

example, accept test results if all challenge water conditions for some replicate tests are within 

70 percent of target values, as long as more than half the replicate trials are above all threshold 

values;
75

• Loosen the requirement that all the biological, physical and chemical challenge water conditions 

must be met for each replicate test of a given BWMS, as long as the majority of threshold 

conditions are met for an individual replicate test; or 

• Allow certain manipulations or alterations to challenge water during testing of BWMS if 

approved by the EPA or the Verification Organization. Acceptance of the conditions would be 

based on either the test facility’s test data or experimental data from other test facilities, showing 

the manipulations do not affect the validity of the test.

6.2.4. Testing Shipboard Treatment Systems: Inherent Mismatch between Viability Standard 

and Practical Protocols

The previous section reviewed features of current procedures for testing BWMS that could be improved 

with existing knowledge and technology. In this section, the Panel reviews additional aspects of current 

procedures that may not accomplish the stated goals because of inherent limitations in current 

knowledge and technology. All of the six issues considered below stem from the difficulty—perhaps the 

impossibility, given current technology—of accurately enumerating only those organisms that are viable 

(living). Current practices result from trying to directly assess the legal standards (which focus on viable 

organisms). This section is aimed especially at organisms < 50 μm, because the challenge of 

determining viability of larger organisms may be secondary to the problem of sampling an adequate 

volume to assess the concentration aspect of the legal standard (see section 3, Statistics and 

Interpretation). The Panel recommends that new approaches be developed, including procedures that 

address the standards indirectly, but have the benefit of practicality. In general, the Panel recommends 

that the limitations of testing protocols for determining “viability” and/or “living” be assessed. Where 

they are found to be lacking, the Panel recommends development of improved standardized protocols. If 

indirect metrics can be reliably correlated with the concentration of viable organisms at land-based test 

facilities, they should also be considered for adoption (as the Panel noted in Table 6-4 above).

As Lee et al. (2010, p. 72) aptly state, “A discharge standard of ‘zero detectable organisms’ may appear 

very protective; however, the true degree of protection depends on the sampling protocol.” Here, a 

viable or living organism is defined as in U.S. EPA (1999), namely, as an organism that has the ability 

to pass genetic material on to the next generation. The percentage of non-viable cells can vary markedly, 

for example, from 5-60 percent among phytoplankton taxa, and in general, non-viable organisms are 

believed to represent a substantial component of the total plankton (Agusti and Sánchez 2002). There are 

several fundamental problems with present attempts to quantify viable organisms to evaluate ballast 

water treatment efficiency, outlined as follows.

Death of Organisms by Rapid Concentration from Large Volumes

A major issue confounding the realistic representation of viable organism concentrations is that the rapid 

concentration of organisms from large volumes into small volumes (which is a necessary prerequisite of 

enumeration) causes the death of many organisms across size classes. This concentration step must be 

accomplished quickly before organisms die, e.g., within six hours (or less) for zooplankton. Because of 

the need to evaluate relatively large volumes of water in order to be confident about the concentrations 

of sparse organisms in treated water, there is a fundamental disconnect in these requirements. It is 

difficult if not impossible to rapidly concentrate microflora and microfauna from relatively large 

volumes (hundreds of liters for zooplankton; liters for protists) by available filtration or centrifugation 
76

techniques without killing some of the organisms (e.g., Turner 1978; Cangelosi et al. 2007). Such rapid 

concentration techniques can cause the loss of a major fraction of the viable organisms, even when 

dealing with small sample volumes such as 1 liter (Darzynkiewicz et al. 1994). This problem affects 

zooplankton and protist size classes, especially delicate species such as wall-less algal flagellates. Thus, 

even if viable organisms can be distinguished from dead organisms when counted, what cannot be 

known is the proportion of the dead organisms that were actually living at the time of sampling. These 

problems illustrate the critical importance of a test facility validating all steps of any method it uses. It 

should be noted that concentration-related losses do not affect the smallest size classes, bacteria and 

viruses, because they are so abundant in most fresh, estuarine, and marine waters that it usually is not 

necessary to concentrate them from whole water samples prior to analysis by standard microbial 

techniques (U.S. EPA 2010; see below).

Organism Viability is Difficult to Determine

Organism viability is not easily detected by a single morphological, physiological, or genetic parameter, 

making it advantageous to use more than one approach (Brussaard et al. 2001). In the context of meeting 

a numeric standard, this approach is problematic because more than one ‘answer’ is generated. 

Furthermore, the procedures used to determine viability are specific to some taxonomic groups (e.g., 

vital stains) and have varying degrees of uncertainty in categorizing live versus dead. Even procedures 

recommended in the Protocol for land-based verification testing have practical limitations because of 

time constraints. For example, the Protocol defines dead zooplankton operationally as individuals that 

do not visibly move during an observation time of at least 10 seconds. Since live zooplankton may not 

move over that short period, death is verified by gently touching the organism with the point of a fine 

dissecting needle to elicit movement. However, the Protocol acknowledges that if every apparently dead 

zooplankter in a concentrated subsample was probed and monitored for at least 10 seconds, the length of 

time to complete analysis of the sample could be extended enough to increase the potential for sample 

bias due to death of some proportion of individuals that had survived the sampling and concentration 

procedures. In other words, the currently applied methods have serious limitations in some situations. 

The results are therefore most appropriately viewed as an index of the number of viable organisms. 

The Protocol is a living document, and as better methods are developed, they will be incorporated. The 

Panel recommends consideration of a wider variety of indices that have the potential to be more rapidly 

completed, if not more accurate. These include parameters that may be correlated to the abundance of 

viable organisms, as discussed in the previous section (Table 6-4), and techniques to distinguish living 

from dead individuals prior to enumeration by other methods (e.g., microscopy). The latter is elaborated 

upon here. 

Fluorescent stains have shown promise in detecting some live organisms or groups. For example, the 

fluorogenic substrate Calcein-AM (Molecular Probes Inc.) is used to stain live cells that have metabolic 

esterase activity (Kaneshiro et al. 1993; Porter et al. 1995). Once the colorless, nonfluorescent substrate 

is inside the living cell, its lipophilic blocking groups are cleaved by nonspecific esterases to a charged 

green fluorescen product that cannot pass across the plasma membrane. Dead cells cannot hydrolyze the 

Calcein-AM or retain the fluorescent product. Use of FDA, sometimes in combination with CMFDA 

(Table 6-3), is based on measuring intracellular esterases in live cells (Laabir and Gentien 1999; Hampel 

et al. 2001). FDA was described as a reliable, efficient method to quantify concentrated viable 

freshwater organisms in the > 10 to < 50 μm size class from ballast discharge (Reavie et al. 2010). 

However, various algal species differ in their uptake of FDA and CMFDA, and other particles in a given 
77

sample can also fluoresce (Garvey et al. 2007; MERC 2009c). The vital stain propidium iodide (PI), in 

combination with molecular probes, has been used to discern live from dead bacteria (Williams et al. 

1998), but the number of false positives can vary widely (Steinberg et al. 2010), and this stain cannot be 

used to assess algal viability because its emission spectrum overlaps that of chlorophyll (Veldhuis et al. 

2001). Consistent with the ETV Protocol (U.S. EPA 2010), the Panel recommends completion of on-site 

validation before selecting a viability method, including evaluation of false positives and false negatives.

As mentioned above, detection of infective viruses has received relatively little attention in ballast water 

treatment. Waterborne illnesses can involve a wide array of viruses; for example, enteric viruses that can 

be transmitted by water include poliovirus, coxsackievirus, echovirus, human caliciviruses such as 

noroviruses and sapoviruses, rotaviruses, hepatitis A virus, and adenoviruses (Howard et al. 2006). 

Considering pathogens of aquatic organisms, aquatic ecosystems are poorly understood with respect to 

the diversity of viral pathogens of beneficial aquatic life (Suttle et al. 1991; Griffin et al. 2003; Munn 

2006; Suttle 2007). Viruses also cross size classes; in environmental samples, many are in range of 

nanometers, but some can be nearly 3 μm in maximum dimension (Bratbak et al. 1992); their tendency 

to adsorb to sediment particles (> 6 μm) means they can be captured with larger particles during sample 

preparation involving filtration (Bosch et al. 2005). 

The U.S. EPA (2001) requires a 99.9 percent reduction in the total number of human enteric viruses in 

water for human consumption. In practice, this requirement is met based on treatment alone, although 

the EPA acknowledges that removal actually can only be accurately assessed by monitoring finished 

waters over time. Ultra-filtration protocols have been developed for concentrating and enumerating 

human enteric viruses (Fout et al. 1996; U.S. EPA 2001), but these techniques do not discern potentially 

infectious from non-infectious viruses. Environmental water samples also have been evaluated for 

human viral pathogens using standard techniques for in vitro cultivation, an approach that is affected by 

the same problems confronted for detection of viable bacteria—the techniques are expensive, timeconsuming, labor-intensive, and can easily miss various groups of infectious viruses (Fout et al. 1996). 

Rapid, sensitive molecular methods for viral nucleic acid detection have been recently developed but, 

again, most cannot discern potential infectivity. The intercalating dye propidium monoazide (PMA) has 

shown promise in detecting potentially infective coxsackievirus, poliovirus, echovirus, and Norwalk 

virus (Parshionikar et al. 2010). In other promising research, Cromeans et al. (2005) included additional 

processing steps such as specific capture by cell receptors for Coxsackie B viruses in vitro, followed by 

molecular detection of viral nucleic acids in the captured viruses; or selection/detection of specific RNA 

present in host cells only during virus replication. Real-time assays (30-90 minutes) were also developed 

for enterovirus, hepatitis A virus, Adenovirus, and Norovirus detection. There remains a need for new, 

commercially available technology that can discern infectious from non-infectious viruses (Cromeans et 

al. 2005; Parshionikar et al. 2010) although current and proposed standards do not distinguish the two. 

Special Challenges of Resistant or Nonculturable Stages in Attempts to Assess Viability

Resting stages (e.g., cysts) of some bacteria, phytoplankton, protists, zooplankton and metazoans are 

particularly resistant to motility, staining, and any other tests. For example, the protist size class (≥ 10 

μm to < 50 μm) includes many species (microalgae, heterotrophic protists, metazoans) that form 

dormant cells or resting stages, or cysts (Matsuoka and Fukuyo 2000; Marrett and Zonneveld 2003). 

Cysts from potentially toxic dinoflagellates are commonly found in ballast waters and sediments 

(Hallegraeff and Bolch 1992; Dobbs and Rogerson 2005; Doblin and Dobbs 2006). These cysts have 

been used as model indicator organisms to assess ballast water treatment efficiency (Anderson et al. 
78

2004; Stevens et al. 2004), based on the premise that treatments which can eliminate the cysts likely also 

eliminate other, less-resistant organisms (Bolch and Hallegraeff 1993; Hallegraeff et al. 1997).

Because resistant cells often have a low metabolic state and thick, multi-layered walls that are 

impermeable to many stains (Romano et al. 1996; Kokinos et al. 1998; Connelly et al. 2007), their 

viability can be difficult to assess without culture analyses that may require weeks to months (Montresor 

et al. 2003; U.S. EPA 2010). Improved methods have been developed for some algal groups (Binet and 

Stauber 2006; Gregg and Hallegraeff 2007) but, overall, as the ETV Protocol (U.S. EPA 2010, pp.46-

47) states, “At present, no rapid, reliable method to determine cysts’ viability is in widespread use, and 

the FDA-CMFDA method has yielded variable results with dinoflagellates and cyst-like objects.” The 

ETV Protocol recommends use of this method as a “place holder” until more effective methods become 

available. 

The effectiveness of ballast water treatment in removing viable bacteria is evaluated by using multiple 

bacterial media in combination with taxon-specific molecular techniques (MERC 2009c; U.S. EPA 2010 

and references therein). Colonies are monitored and quantified after ~1 to 5 days, depending upon the 

organism and its growth. These methods enable detection and quantification of viable, culturable cells. 

However, it has been repeatedly demonstrated that bacterial consortia across aquatic ecosystems 

commonly have a substantial proportion of cells that are active (viable) but nonculturable (Oliver 1993;

Barcina et al. 1997 and references therein). These cells obviously would be overlooked in culturing 

techniques, a problem that would result in failure to detect viable cells of bacterial pathogens in treated 

ballast water. Under some conditions, the nonculturable organisms can regain activity and virulence 

(Barcina et al. 1997 and references therein).

Biased Counts Due to Live, Motile Species Changing their Location in Counting Chambers

At the other extreme from resting stages are living organisms that are difficult to enumerate because 

they are highly mobile. Organisms are typically enumerated in counting chambers, based upon an 

underlying premise that the cells do not change their location in the chamber. However, many protists 

move rapidly by means of flagella or other structures. Because they do not maintain their position in a 

counting chamber, as live cells they could be counted multiple times. Moreover, their sudden movement 

can disrupt the locations of other cells in the chamber, mixing cells that may have been counted with 

others that have not yet been counted. For these reasons, reliance on live counts can easily yield 

unreliable data. This consideration underscores the need for vigorous validation of protocols used to 

quantify viable organisms. 

Indirect Metrics for Enumeration of Viable Cells Should be Investigated for Use in Standard 

Protocols

Consideration of the above points—death during concentration of organisms, lack of reliable procedures 

to assess viability (especially for resting stages of many taxa), movement of live organisms in counting 

chambers that can result in serious quantification errors—leads the Panel to recommend that alternative 

approaches, including enumeration of preserved organisms and indirect metrics of the concentration of 

viable organisms, be tested. Should they be validated as superior to present protocols, then the argument 

is strong to consider elevating these alternative approaches to standard protocols. These inherent 

limitations add weight to the more practical considerations in section 6.2.3 above: the practical and 

inherent limitations converge as an argument for the greater development, testing and implementation of 
79

indirect metrics of the concentration of viable organisms, including both STOs and surrogate 

parameters, particularly in compliance testing. Adding parallel testing of indirect metrics to land-based 

testing currently underway in test facilities from different geographic regions could rapidly yield 

comparisons on which decisions for future testing could be made. Possibly, a combination of approaches 

will prove to be the most advantageous in estimating the concentration of viable organisms of different 

taxonomic groups.

6.3. Approaches to Compliance/Enforcement of Ballast Water Regulations and Potential 

Application to Technology Testing

The EPA has extensive experience in effective compliance and enforcement of discharge regulations, 

and has committed to work with the USCG to develop and implement compliance and enforcement 

measures for ballast water regulations (2011 MOU between EPA and USCG6). However, given the 

nature of ship ballast water discharge, new approaches likely will be needed. Both initial testing of 

treatment systems (6.2.2 – 6.2.4) and methods currently available for potential compliance and 

enforcement monitoring are complex, slow and expensive. Statistical (see section 3, this report) and 

logistical limitations related to collection of appropriate sample volumes and detection/quantification of 

live organisms in practice, mean that it may often be impossible to directly assess whether a vessel can 

meet all the numerical standards for viable organisms (King and Tamburri 2010). No information was 

provided to the Panel on whether protocols and systems for compliance monitoring (whether voluntary 

by ship operator or legally required) and enforcement were being considered alongside the development 

and testing of treatment systems. The Panel considers it essential that these be developed so enforcement 

can commence as soon as a U.S. ballast water performance standard is finalized.

The practical and inherent limitations suffered by the full protocols for verification testing of BWMS 

(6.2.2 – 6.2.4) have even greater force in the context of routine inspections (either self-inspections or 

regulatory inspections) (King and Tamburri 2010). They are simply not practicable to use in the 

compliance and enforcement context. Unless alternative protocols that are practical for inspections are 

developed, neither self-compliance efforts nor regulatory enforcement will be possible once a system is 

installed on a ship. For example, treatment system malfunctions are inevitable. If some types of 

mechanical failure are not obvious to the operator or inspector, release of organisms may reach and 

maintain non-compliant levels for long periods of time with no detection of the malfunction, no penalty, 

and therefore no incentive to detect and fix the system. Unenforceable rules are bound to fail to meet the 

goal of reducing invasions. Therefore, the Panel recommends that the EPA develop an approach for

BWMS that includes metrics appropriate for compliance monitoring and enforcement.

A potential solution is the use of a step-wise compliance reporting, inspections, and monitoring 

approach, described below, which involves a series of steps that increase the likelihood of detecting noncompliance but also increase in cost and logistic challenges (King and Tamburri 2010). 

• Reporting. Vessel owner or ship master submits reports on the type of certified treatment 

system onboard and documentation demonstrating appropriate use and maintenance. 

 6 February 2011 Memorandum of Understanding Between the U.S. Environmental Protection Agency, Office of 

Enforcement and Compliance Assurance and the U.S. Coast Guard, Office of Marine Safety, Security and Stewardship for 

Collaboration on Compliance Assistance, Compliance Monitoring, and Enforcement of Vessel General Permit Requirements 

on Vessels (available at http://epa.gov/compliance/resources/agreements/cwa/mou-coastguard-vesselpermitrequirements.pdf)
80

• Inspections. Enforcement official boards vessel and inspects the certified treatment systems 

to verify use and appropriate operations and maintenance. 

• Measures of system performance. Indirect or indicative water quality measures are collected 

autonomously (using commercially available instruments), or by inspectors, that demonstrate 

appropriate treatment conditions have been met.

• Indirect measures of non-compliance. Indirect metrics (e.g., Table 6-5) of abundances of live 

organisms are collected autonomously, or by inspectors, for indications of clear noncompliance. 

• Measures of performance standard. Direct measures of concentration of live organisms in 

the various regulated categories are made by specially trained technicians, with statistically 

appropriate sampling and validated analyses and methodologies.

Protocols assessing indirect surrogate measures to quantify viable organisms should be further 

developed for quick, easy, and defensible shipboard compliance monitoring (see 6.2.2 - 6.2.4). 

6.4. Reception Facilities as an Alternative to Shipboard Treatment

Proposed federal regulations and the IMO Ballast Water Management Convention allow for the transfer 

of vessel ballast water to reception facilities, where the organisms in ballast water would be removed or 

inactivated. Various studies have envisioned reception facilities as either built on land or installed on 

port-based barges or ships. The discussion here refers to the use of on-land facilities, unless otherwise 

specified. 

Ballast water would be pumped off a vessel to a reception facility through main deck fittings and piping 

or hoses similar to those currently used to transfer oil or other liquid cargo, oil-contaminated ballast 

water, or fuel oil between vessels and shore. Vessels would need to be outfitted with appropriate pipes 

and pumps to move ballast water to the deck and off the ship at a fast enough rate so the vessel is not 

unduly delayed in port. The reception facility would store and treat the ballast water before discharging 

it to local waters.

Vessel architecture and operations are principal impediments to the development of shipboard BWMS. 

Challenging factors include vibration, small and busy crews, limited space and weight allowances, 

limited power, potentially increased corrosion rates and sometimes short voyages. Reception facilities, 

relieved of many or all of those constraints, show promise to achieve more stringent ballast water 

treatment standards than shipboard BWMS.

The Panel did not reach consensus on certain issues and analyses related to treatment of ballast water at 

reception facilities. Issues on which the Panel reached consensus are described in sections 6.4.1 and 

6.4.2 (although two points of view are included for one of the issues). Panel conclusions on reception 

facilities are presented in section 6.7.

6.4.1. Potential of Reception Facilities to Cost Effectively Meet Higher Standards

Though various studies, regulations and guidelines recognize the potential of reception facilities to treat 

ballast discharges, the EPA and USCG reports on ballast water treatment have not addressed reception 

facilities (EPA 2001; Albert et al. 2010; USCG 2008a,b). The literature on onshore treatment is 

reviewed in Appendix B. Some studies conclude that reception facilities are a technically feasible option 
81

for either the industry as a whole or for some part of the industry (Pollutech 1992; NRC 1996; Oemke 

1999; CAPA 2000; California SWRCB 2002; Brown & Caldwell 2007, 2008). Other studies conclude 

that cost or other factors could limit the use of reception facilities to part of the industry (Victoria ENRC 

1997; Dames & Moore 1998, 1999; Rigby and Taylor 2001a, b; California SLC 2009, 2010).

Four studies compared the effectiveness or costs of reception facilities and shipboard treatment.

Pollutech (1992) ranked reception facilities second in terms of effectiveness, feasibility, maintenance 

and operations, environmental acceptability, cost, safety and monitoring out of 24 ballast water 

management approaches for Great Lakes vessels; this study ranked shipboard filtration through a 50 μm 

wedgewire strainer higher, and 17 other shipboard treatments lower, than treatment by a reception 

facility7

. AQIS (1993a) found reception facilities (considering both on land and barge-mounted 

facilities) to be less expensive than shipboard treatment in both single-port and nation-wide scenarios in 

Australia, concluding that reception facilities “are more economic and effective than numerous shipboard plants.” Aquatic Sciences (1996) estimated the costs of using barge-mounted reception facilities in 

the Great Lakes, and concluded that it is technically feasible, “more practical and enforceable” than 

shipboard treatment, and offers “the best assurance of prevention of unwanted introductions.” California 

SWRCB (2002) found reception facilities to be the only approach to have acceptable performance in all 

three categories of effectiveness, safety, and environmental acceptability in a qualitative comparison 

with 10 shipboard treatments. Cost estimates compiled by the U.S. Coast Guard (e.g., USCG 2002) 

showed reception facilities to be generally less expensive on a per metric ton basis than shipboard 

treatment, although these estimates predate the establishment of discharge regulations and the most 

recent generation of BWMS. In fact, most of the existing studies and estimates use outdated assumptions 

or data, or are based on specific regions; therefore their conclusions may not apply to the current U.S. 

situation, nor do they address international shipping issues.

The potential advantages of reception facilities over shipboard treatment systems include: fewer 

reception facilities than shipboard systems would be needed; smaller total treatment capacity would be 

needed; and reception facilities would be subject to fewer physical restrictions, and would therefore be 

able to use more effective technologies and processes such as those commonly used in water treatment. 

A shift from shipboard treatment to reception facilities is in some ways analogous to a shift from 

household septic tanks to centralized wastewater treatment plants. These advantages are discussed in 

greater detail in the following paragraphs. 

Treatment Capacity 

The EPA estimates that approximately 40,000 cargo vessels and 29,000 other vessels will be subject to 

ballast water discharge requirements in the U.S. over the five-year VGP period (Albert and Everett 

2010); approximately 7,000 ocean-going vessels called at U.S. ports in 2009 (MARAD 2011). Using 

reception facilities would reduce the number of treatment plants and the total treatment capacity needed 

for ballast water management. In shipboard treatment, a plant is installed on each vessel, and for nearly 

all types of BWMS this must be large enough to treat the vessel’s maximum ballast uptake or discharge 

rate (Lloyd’s Register 2010). The total treatment capacity needed is thus equal to the sum of the 

maximum uptake or discharge rate of all ships. In contrast, reception facilities serve a number of vessels, 

and since all vessels do not arrive and discharge ballast water simultaneously, the treatment capacity 

needed would be less. Ballast water storage tanks at reception facilities would further lower the needed 

treatment capacity, potentially to the average ballast water discharge rate. However, existing studies do 

 7 The remaining 5 management approaches involved neither shipboard treatment nor reception facilities.
82

not appear sufficient to reliably estimate total treatment capacities required for individual BWMS versus 

a national U.S. network of reception facilities. If undertaken, such studies would benefit from explicit 

statements of assumptions about what drives treatment capacity needs and from comparisons of capacity 

estimates derived from a range of assumptions.

Constraints on Treatment

Constraints on onboard treatment include limited space, power and treatment time, and ship stability 

challenges (Pollutech 1992; AQIS 1993a; Aquatic Sciences 1996; NRC 1996; Cohen 1998; Oemke 

1999; Reeves 1999; California SLC 2010; Albert and Everett 2010). These constraints are largely absent 

in reception facilities, 

Efficacy of Treatment Methods 

Any treatment used on vessels could be used in reception facilities; alternatively, there are methods 

available for reception facilities that cannot be used on vessels because of the space and other constraints 

listed above. Such technologies include common water or wastewater treatment processes, such as 

settling tanks and granular filtration, and less common processes including membrane filtration (AQIS 

1993a; Gauthier and Steel 1996; NRC 1996; Victoria ENRC 1997; Reeves 1999; Cohen and Foster

2000; California SWRCB 2002; California SLC 2010).

The following information illustrates what could be achieved by using available water/wastewater 

technologies in reception facilities; it describes what can be achieved in drinking water treatment 

systems, recognizing that reception facilities would have to deal with a much greater taxonomic

diversity of organisms (from large zooplankton to microbes) and be able to effectively treat all possible 

salinities (not just freshwater). For example, testing protocols for shipboard BWMS require at least a 

four-log reduction in the ≥ 50 um size class, and at least a two-log reduction in the ≥ 10 to < 50 μm size 

class when compared to ballast water uptake conditions. These metrics, however, do not account for 

organism mortality in ballast water that occurs even with untreated ballast water. As this mortality varies 

significantly (in some cases resulting in one-log reductions), it is difficult to quantify efficacy in terms 

of log reductions. As such, Table 6-6 below compares the level of treatment that would be required for 

two discharge standards relative to mean organism counts taken from vessels after a voyage. The Panel

recognizes that there may be valid ways of assessing efficacy other than basing it on mean 

concentrations. 

Table 6-6. Log reductions required by different discharge standards. Reductions are from mean values reported

by IMO (2003) for unexchanged and untreated ballast water sampled from vessels at the ends of voyages, for 

zooplankton (n=429, collected with 55-80 μm mesh nets, corresponding approximately to organisms in the ≥50 μm 

size class), phytoplankton (n=273, collected with <10 μm mesh sieves or counted in unconcentrated samples, 

corresponding approximately to organisms in the 10-50 μm class), bacteria (n=11) and virus-like particles (n=7).

≥ 50 μm

Organism/size class:

≥ 10 - < 50 μm Bacteria Viruses

Discharge standard per m3 per ml per ml per ml

IMO D-2 and USCG Phase 1 2.7 1.5 no reduction no reduction

USCG Phase 2 5.7 4.5 4.9 4.9
83

EPA requires that drinking water treatment systems be capable of at least 3-5 log reductions in Giardia8

, 

3-5.5 log reductions in Cryptosporidium9

, and 4-6 log reductions in viruses, depending on the source 

water (US EPA 1991, 2006). Several common drinking water filtration technologies are capable of 3-4 

log reductions in protozoans and bacteria and 2-4 log reductions in viruses, and membrane filtration can 

achieve >4-7 log reductions (U.S. EPA 1991, 1997b; NESC 2000a; LeChevallier and Au 2004; Wang et 

al. 2006; WHO 2008). UV disinfection can achieve 2-3 log reductions in protozoans and 3-4 log 

reductions in bacteria and viruses; biocides can achieve at least three-log reductions in Giardia, 3-6 log 

reductions in bacteria, and 3-4 log reductions in viruses depending on dose and contact time (U.S. EPA 

1997b; Sugita et al. 1992; NESC 2000b; LeChevallier and Au 2004). Filtration and disinfection are 

generally considered additive processes: that is, a filtration process can produce a 3 log reduction, and a 

disinfection process can produce a two-log reduction, and in sequential combination could potentially 

produce a five-log reduction (U.S. EPA 1991). 

Thus, even without a disinfection step, it appears that several common drinking water filtration 

technologies available for reception facility use could achieve the 1.5-2.7 log reductions from mean 

ballast water concentrations needed to meet the IMO D-2 and USCG Phase 1 standards, although this 

has not been tested with ballast water. It has not been demonstrated that these technologies could 

address the extremely high numbers of organism found in the ballast water of vessels after some 

voyages. Several combinations of filtration plus a single disinfection process appear to be able to 

achieve the 4.5-4.9 log reductions needed to meet the USCG Phase 2 requirements for viruses, bacteria 

and organisms in the ≥ 10 to < 50 μm size class, and perhaps also the 5.7 log reduction needed to meet 

the USCG Phase 2 standard for organisms ≥ 50 μm Treating with one or more additional disinfection 

processes could produce greater log reductions.10

Some membrane filtration technologies that could be used in reception facilities have produced results 

of no detectable organisms in different organism classes. For example, the microfiltration unit used in 

the conceptual design for a reception facility at the Port of Milwaukee (Brown & Caldwell 2008) would 

likely result in no detectable organisms in both the ≥ 50 μm and ≥ 10 to < 50 μm size classes (based on 

microfiltration results cited in U.S. EPA 1997b and LeChevallier and Au 2004). On the other hand, 

ultrafiltration or nanofiltration might be needed to leave no detectable bacteria or viruses in the effluent, 

although the time required to filter water to this level and its effect on vessel operations has not been 

evaluated.

Plant Operation by Trained Water/Wastewater Treatment Personnel

Shipboard BWMS likely would be operated and maintained by regular crew members as added duties 

(NRC 1996; California SLC 2010). Studies have noted that many of these crews are already 

overburdened. Operation by trained, dedicated personnel in reception facilities would likely result in 

more reliable performance (Cohen 1998; California SWRCB 2002; Brown & Caldwell 2007; California 

SLC 2010). Maintenance and repair work are more likely to be done reliably, and replacement parts 

obtained more quickly, in reception facilities (AQIS 1993a; Aquatic Sciences 1996; Cohen 1998). 

 8 A protozoan pathogen with an active form measuring approximately 3 x 9 x 15 μm and an ellipsoid cyst averaging 10-14 

μm long. 

9 A protozoan pathogen with round cysts 4-6 μm in diameter. 10 Sequential combinations of some disinfectants produce reductions even greater than the sum of the disinfectants’ 

reductions when examined separately (LeChevallier and Au 2004).
84

Safety

Restricted working spaces and difficult or hazardous working conditions at sea (AQIS 1993a; Cohen 

1998; Cohen and Foster 2000) increase the risk of accidents with shipboard treatment. The storage and 

use of biocides or other hazardous chemicals pose greater risks to personnel on vessels than in reception 

facilities (AQIS 1993a; Carlton et al. 1995; Reeves 1998; Cohen 1998) and greater risk of accidental 

discharge to the environment (Pollutech 1992; AQIS 1993a; Carlton et al. 1995). Because some physical 

treatment processes cannot be used onboard, shipboard systems might rely on biocides more than would 

reception facilities.

On the other hand, increased safety risk and a risk of spills or leaks of untreated ballast water may 

accompany transfers of ballast water to reception facilities. Although liquid transfer is common practice 

for tank ships, many other ships do not have crews experienced in these operations, and safety training 

would be needed.

Reliability

Operation and maintenance by dedicated wastewater treatment staff should make the reliability of 

reception facilities greater than that of shipboard BWMS. Extensive, long-term experience with water 

and wastewater treatment technologies provides a basis for estimating the expected long-term 

performance of these technologies if employed in reception facilities, while the brief and limited 

experience with shipboard BWMS provides little basis for assessing whether they are likely to perform 

adequately over a 20-to-30-year vessel lifetime. Since many BWMS treat ballast water on uptake 

(Lloyd’s Register 2010), which many vessels hold in dedicated ballast tanks where cysts or other resting 

stages may be retained in sediments for long periods (Cohen 1998), failure to operate a BWMS or to 

operate it effectively at any time could contaminate treated ballast water on later voyages (AQIS 1993a; 

Reeves 1998). In addition, reception facilities would have more flexibility to build redundancy into the 

system design than would shipboard systems. 

Adaptability

Because of space restrictions on vessels and structural cost factors that make treatment components a 

smaller part of the total cost of reception facilities, it is likely to be both physically and financially easier 

to retrofit, replace or upgrade reception facilities than shipboard systems. Reception facilities “provide 

treatment flexibility, allowing additional treatment processes to be added or modified as regulations and 

treatment targets change” (Brown & Caldwell 2008). 

Compliance Monitoring and Regulation

Although the requirements for demonstrating compliance with ballast water discharge regulations have 

yet to be established, the effort and cost of monitoring and enforcement needed to meet a given standard 

could be much less for a small number of reception facilities compared to a larger number of mobile, 

transient, shipboard plants, most of which are foreign-owned or foreign-flagged, which are accessible 

only when in U.S. ports, usually for brief periods (AQIS 1993a; Ogilvie 1995; Aquatic Sciences 1996; 

Cohen 1998; Dames & Moore 1999; Oemke 1999; California SWRCB 2002; Brown & Caldwell 2007; 

California SLC 2010). Some studies noted that only reception facilities put the responsibility for 

monitoring, control and effectiveness entirely in the hands of the authorities responsible for protecting 
85

the receiving waters, without reliance on marine vessel logs or on authorities in originating ports (AQIS 

1993b; Dames & Moore 1999; California SWRCB 2002).

6.4.2. Challenges to Widespread Adoption of Reception Facilities in the U.S.

Although reception facilities offer advantages as just discussed, the Panel recognizes that there are 

challenges to their adoption. The Panel reached consensus on all but one of the challenges presented in 

this section, and opposing views are presented for that one. 

Ballast Discharge Before Arrival to Reduce Time Spent at Berth

Some vessels may discharge part of their ballast water before arriving at berth so they can complete 

discharge by the time the cargo is loaded (AQIS 1993a; Oemke 1999; Cohen and Foster 2000; CAPA 

2000; Rigby and Taylor 2001a). Alternatively, a ship’s ballast water system can be outfitted with pipes 

and pumps that are large enough to allow the ship to unload ballast water as quickly as it loads cargo 

(AQIS 1993b). Glosten (2002) and Brown & Caldwell (2007, 2008) identified technical solutions for 

retrofitting a variety of vessels (but not all types) to allow them to deballast at berth during the time they 

load cargo. However, this issue has not been studied with respect to costs or feasibility for handling as 

yet uncertain estimates of the numbers of vessels expected to require treatment at different ports. 

Ballast Discharge to Reduce Draft Before Arriving at Berth

Several studies noted that some vessels discharge ballast water before arriving at berth to reduce draft to 

cross shallows (Cohen 1998; Dames & Moore 1998, 1999; Oemke 1999; CAPA 2000, Rigby and Taylor 

2001a; California SWRCB 2002; California SLC 2010). The frequency of these occurrences has not 

been quantified (one authority the Panel consulted stated that they are rare whereas another indicated 

that some Great Lakes operators may perform such discharges routinely). Possible solutions include 

offloading ballast water to barges as is done for some liquid cargos (AQIS 1993a; Carlton et al. 1995; 

Dames & Moore 1999; CAPA 2000; Rigby and Taylor 2001a; Glosten 2002; California SWRCB 2002), 

or importing cargo in shallower-draft ships. Dames & Moore (1998) suggested that a barge- or shipmounted reception facility could service deep-drafted arrivals that need to deballast during approach. 

Some panel members point out that this issue has not been studied with respect to costs or feasibility for 

handling as yet uncertain estimates of the numbers of vessels expected to require treatment at different 

ports.

Ballast Discharge by Lightering Vessels

Large tankers that arrive on the U.S. coast carrying crude oil or other liquid cargo may transfer part of it 

to lightering vessels (smaller tankers or barges) in designated anchorages or lightering zones. These 

lightering vessels often discharge ballast as they load cargo. In many cases, the discharged ballast water 

is from nearby sites (CDR Gary Croot, U.S. Coast Guard, pers. comm.; National Ballast Information 

Clearinghouse data), and depending on how the regulations are written may not require treatment.11

 11 EPA’s current Vessel General Permit requires vessels on nearshore Pacific Coast voyages to conduct ballast water 

exchanges only if they cross international boundaries or cross from one Captain of the Port Zone to another (VGP §2.2.3.6). 

Similarly the U.S. Coast Guard’s proposed discharge standards would not apply to vessels operating within a Captain of the 

Port Zone (USCG 2008c).

In 

cases where the ballast water is from more distant sites, solutions might include offloading ballast water 
86

to lightering vessels that have been ballasted with local water, or importing cargo in smaller tankers. The 

frequency, volumes, and uptake and discharge locations associated with lightering have not been 

quantified, so the significance of this issue with respect to invasions or feasibility of technical solutions 

is not known.

Implementation Schedule

It typically takes up to 30 months to design, permit and construct a sewage treatment plant larger than 10 

mgd, and potentially much longer if sites are scarce, or if there are issues related to permit approvals 

(Robert Bastian, U.S. EPA Office of Water, pers. comm.). Most ballast water reception facilities needed 

in the U.S. would be smaller. Vessel modifications are needed for either shipboard or reception facility 

approaches, either to install a BWMS or to allow rapid discharge to a reception facility. This process is 

almost exclusively undertaken while the vessel is out of service, which occurs infrequently; dry 

dockings, by marine vessel classification society requirement, must be no less than once every five years 

(ABS SVR 7/2/1-11). To accommodate vessel modifications, proposed standards include phase-in 

periods (8 years for IMO D-2, 9 years for USCG Phase 1). The critical path for both reception facility 

and shipboard treatment is the vessel modification work, where the governing factor is the frequency 

with which the vessel is taken out of service. This is the same for either approach. 

A more comprehensive comparison of potential implementation schedules for both shipboard BWMS 

and reception facilities is needed.

The Current Regulatory Framework

Challenges associated with the regulatory framework are included in this section even though the Panel 

did not reach consensus on this issue, because many Panel members thought that this is the major 

challenge to reception facilities; therefore leaving it out would result in an unbalanced portrayal of 

advantages and challenges. Two views of the issue are presented here. 

View 1: Although reception facilities are allowed in policy and rules and have identified 

advantages relative to BWMS, there are no reception facilities currently available in the U.S. to 

remove organisms from ballast water. At the same time, there are 10 internationally Type 

Approved BWMS of which many have been sold. This appears to be a result of the framework of 

the 2004 IMO Convention that phases in performance standards by marine vessel ballast water 

capacity and construction date of marine vessels rather than on a port-by-port basis. To avoid the 

risk of arriving in a port without an operational reception facility, operators are opting to install 

shipboard BWMS. The U.S. proposed Phase 1 timetable would require all new vessels 

constructed starting in 2012 to meet performance standards upon delivery. To be in compliance 

using only reception facilities, the marine vessel operator must be assured that there will be an 

operational reception facility at all anticipated ports-of-call where ballast water discharge might 

be expected for the lifetime of the vessel. On the other hand, vessels engaged solely in regional 

trade may benefit from the reception facility approach if reception facilities are operational in the 

region and will not need to invest in a shipboard BWMS.

• View 2: The alternative view holds that current federal regulations governing ballast discharges 

under NISA and CWA are based on mid-ocean exchange (Albert et al. 2010), and thus favor 

neither BWMS nor reception facility treatment. Various states have adopted discharge standards, 
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of which some might be met by BWMS, while others would require reception facility treatment 

because their requirements are more stringent. Regulatory agency dismissal of or opposition to 

reception facilities, and encouragement of BWMS (including the sponsorship and funding of 

research), has contributed to the focus on BWMS. Equipment manufacturers have invested in the 

development of BWMS because they expect that discharge standards that can be met by BWMS 

will be implemented and enforced, thereby creating a large enough market to allow them to 

recoup their investments and turn a profit. Ports have not promoted the development of reception 

facilities because they are not convinced that discharge standards requiring treatment in reception 

facilities will be implemented and enforced effectively. If equipment manufacturers and ports 

come to believe that standards will be implemented that will need to be met by treatment in 

reception facilities—then the current focus on BWMS will shift. It is the decisions, actions and 

communications of regulatory agencies that will mold these expectations about the future 

direction and implementation of discharge standards.

Issues regarding treatment in reception facilities for which the Panel did not reach consensus

There were several additional issues regarding treatment in reception facilities for which the Panel did 

not reach consensus. Included below is a brief summary of discussions that may be helpful to the ballastwater community in the future. 

• Need for further study. The Panel discussed the need for further study of BWMS treatment 

options. Some Panelists, noting the scarcity of reliable test data, discussed the need for further 

study of long-term performance of shipboard BWMS under the challenging conditions of actual 

shipboard use. Some Panelists discussed the need for pilot studies of reception facilities to assess 

their cost, operations, and safety issues in order to assess systemic challenges and to support 

operational solutions for creation of networks of onshore reception facilities.

• Cost comparison. The Panel did not reach agreement on issues relating to estimating and 

comparing the cost of treating ballast water in shipboard BWMS and the cost for treating in 

onshore reception facilities. There were differing opinions on the assumptions needed to develop 

screening estimates for either option. These included assumptions about capacity requirements, 

applicability of existing cost data, extrapolation methods, inclusion of operational costs that 

could be incurred by vessel owners if they were delayed due to unavailability of reception 

facilities or from inoperable BWMS, and costs for some vessel owners that might be required to 

install a shipboard BWMS as well as pay for use of a reception facility, depending on the port of 

call.

• Implementation issues. The Panel discussed issues that could affect the time needed to 

implement treatment of ballast water by individual shipboard BWMS or for developing a 

network of reception facilities, but did not come to agreement on their implications for

implementation timelines. Some panel members said that reliance on shipboard BWMS would 

require a potential lag of several years for large-scale production of BWMS and time needed to 

develop effective monitoring and enforcement. Some members said that timelines for developing 

reception facilities would need to consider implications of land availability adjacent to port 

terminals, and time to acquire and permit newly designed treatment facilities and required 

support services. 
88

International issues. The Panel briefly discussed international issues related to potential new 

U.S. standards for ballast water discharge. These issues included the complexities of 

implementing standards for vessels engaged in international maritime trade. The Panel also 

briefly discussed whether setting U.S. standards based on the likely higher performance of 

reception facilities would introduce potentially varying levels of protection against introduction 

of invasive species among the U. S. and other countries. 

6.5. Approaches Other than Ballast Water Treatment

Several approaches other than the treatment of ballast water could help to reduce the risk of biological 

invasions from ballast water discharges, and contribute to the achievability of performance standards 

and permit requirements. While these approaches are often recommended, including by IMO, they are 

not often required or incentivized in practice. These approaches include ballasting practices to reduce 

the uptake of organisms, ballast water exchange to reduce the concentration of exotic organisms, 

reductions in the volume of ballast water discharged in U.S. waters, and management of the rate, pattern 

or location of ballast water discharge to reduce the risk of establishment. Although the charge questions 

to the Panel focused on shipboard treatment, the Panel considered these other approaches because, when 

used in combination with shipboard treatment, they appear to be capable of achieving a greater level of 

risk reduction than shipboard treatment alone.

6.5.1. Managing Ballast Uptake

Several studies have recommended various ballasting practices—sometimes referred to as ballast micromanagement (Carlton et al. 1995; Oemke 1999; Dames & Moore 1998, 1999; Cohen and Foster 2000), 

shipboard management measures (Gauthier and Steel 1996), or precautionary management measures 

(Rigby and Taylor 2001a,b)—to reduce the number of organisms, or the number of harmful or 

potentially harmful organisms (such as bloom-forming algae and human pathogens found in sewage), 

that are taken up with ballast water It is suggested that this can be accomplished by managing the time, 

place and depth of ballasting. Some of these measures have been included in laws, regulations or 

guidelines, including IMO guidelines and the USCG rules implementing the National Invasive Species 

Act. Although some of these regulations or guidelines have been in effect for nearly 20 years, there 

appear to be no data on levels of compliance and no studies of the effectiveness of any of these measures 

in reducing the uptake of organisms. 

While there may be reasons for skepticism regarding the effectiveness or feasibility of several of these 

measures (AQIS 1993b; Cohen 1998; Dames & Moore 1998, 1999; Cohen and Foster 2000; Rigby and 

Taylor 2001b), some could be helpful in meeting stringent standards if vessels had sufficient incentive to 

implement them. The effectiveness of alternative ballasting (e.g., at locations low in harmful organisms) 

and deballasting practices (e.g., locations and practices to reduce concentrating propagules) should be 

quantified. As an example of the former, researchhas shown that taking up ballast water in areas affected 

by toxic dinoflagellate blooms, followed by deballasting in another location, can result in distribution of 

those blooms to previously unaffected areas (Hallegraeff and Bolch 1991). Clearly, such action should 

be avoided as routine practice, and can also help to meet BWMS standards.

The value of such practices could be evaluated with models using currently available data on organism 

distributions or by experimental approaches. To the extent these practices would reduce the uptake of 

organisms, they could be used by vessels to help them meet any performance standards that might be 
89

adopted. From the perspective of overcoming technical limitations on the feasibility of meeting different 

performance standards, such practices might allow the adoption of -- and vessel compliance with -- 

more stringent standards than would otherwise be achievable. Thus, there are valid reasons for the EPA 

to consider the potential for employing these practices in combination with ballast water treatment to 

further reduce the risk of releasing exotic organisms in U.S. waters.

6.5.2. Mid-ocean Exchange

Mid-ocean ballast water exchange has the potential, in combination with the other approaches discussed 

here, to further reduce the concentration of exotic organisms (though not necessarily reduce the 

concentration of all organisms) in ballast discharges. There is general agreement that when properly 

done, ballast water exchange can reduce the concentration of initially loaded organisms by about an 

order of magnitude on average (Minton et al. 2005). It is not however, always possible, especially for 

short coastal voyages. Additionally, conducting exchange represents an additional cost to the vessel.

6.5.3. Reducing or Eliminating Ballast Water Discharge Volumes

Invasion risk is positively related to the total number of propagules released in a given time and place. 

Thus, risk is positively related to the concentration of propagules times the volume of the discharge. 

Even if the concentration of propagules is unmanaged, reducing discharge volumes will reduce invasion 

risk in ways that are predictable across taxa (Drake et al. 2005). Given this, various alternatives to the 

use of “conventional” ballast water management systems have been proposed and studied since the 2004 

IMO Ballast Water Management Convention. These emerging alternatives to shipboard BWMS include 

concepts and designs for “ballastless” or “ballast-free” ships, “ballast-through” or “flow-through” ships, 

the use of “solid-ballast”, and the use of “freshwater ballast”. In fact, Regulation B-3, of the IMO 

Convention predicts and allows for the development and future use of such approaches to prevent the 

transport of invasive species by ships. These approaches are summarized below. 

Ballastless ship designs constitute a fundamental paradigm shift in surface vessel design. Rather than 

increasing the weight of vessels by adding water to ballast tanks, these new designs use reduced 

buoyancy to get the ship down to safe operating drafts in the no-cargo condition. For example, the 

Variable Buoyancy Ship design (Parsons 1998; Kotinis et al. 2004; Parsons 2010) achieves this end by 

having structural trunks of sufficient volume that extend most of the length of the ship below the “ballast 

waterline” and then opening these trunks to the sea in the no-cargo condition. When the ship is at speed, 

the natural pressure difference between the bow and the stern induces flow through the open trunks, 

resulting in only local water (and associated organisms) within trunks at any point during a voyage. 

While showing promise, and worthy of further considerations, ballastless ship designs appear feasible 

only for new vessels being built in the future and may result in an overall increase in vessel biofouling 

(another significant source of invasive species), if surfaces in open flow-through spaces are more 

accessible and hospitable than traditional ballast tank surfaces (which are rarely fouled by higher 

organisms). Similarly, a return to a historic approach of using solid ballast (commonly iron, cement, 

gravel or sand) has been discussed recently but may not be feasible or cost effective for most vessels in 

the modern merchant fleet. 

Marine vessels that carry cargo in bulk, such as oil tankers or dry bulk carriers, cannot generally avoid 

discharging ballast water in a cargo loading port. Part of the weight of the discharged bulk cargo, 

typically 50 percent, must be replaced with ballast water to maintain stability. However, there are other 
90

vessel types, such as passenger ships and container ships, which do not experience the same bulk shift in 

cargo that demands immediate ballast water replacement. These vessels provide opportunities for 

innovative designs and operational practices that can significantly reduce or even eliminate ballast water 

discharges in port.

Innovations to reduce ballast have also occurred in other types of vessels. Some vessels only require 

ballast water to replace fuel oil consumption. A recent research vessel design was able to use the 

processed effluent from the marine sanitation devices as ballast water. The mass balance between the 

crew’s gray and black water waste was similar to the amount of ballast water required to account for 

consumed fuel oil. This approach eliminated traditional sea water ballast from the vessel design. The use 

of freshwater as ballast has also been proposed, either the onboard production of potable water as ballast 

for smaller vessels to replace fuel consumption or the transportation of freshwater from one port to 

another that might have limited supplies of drinking or agricultural water (e.g., Suban et al. 2010). Using 

a similar principle of only local water being onboard a vessel at any one time, other sorts of flowthrough ballast systems have also been proposed. These approaches would likely require modifications 

to the existing ballast systems to actively and continuously pump water in and out of the ballast tanks 

throughout voyages, resulting in complete tank turnover in an hour or two. 

Container ships can sometimes balance operations between loaded cargo and discharged cargo. Even 

when not balanced, the weight differential may often be within the margins of the vessel trim and 

stability requirements. One company has built and is operating two trailer-ships, similar to container 

ships that used design trades to eliminate the use of seawater ballast in all cases except emergencies. The 

ships are a bit wider, and potentially burn some additional fuel to account for their increased size. 

However, they have eliminated ballast water movements, as well as maintenance efforts associated with 

salt water piping systems and ballast tanks. Trim corrections are accounted for by shifting ballast water 

between tanks.

Given increased scrutiny and demands for ballast water exchange, it appears that many operators have 

been able to reduce or eliminate their discharges through careful operational practices, e.g., members of 

the Pacific Merchant Shipping Agency (PMSA) “all practice ballast water management protocols to 

reduce or eliminate the risk of introduction of aquatic invasive species in state waters . . . Over 80 

percent of vessels hold all ballast water in port to eliminate this risk. Those vessels that must discharge 

ballast ensure that it is exchanged with mid-ocean water prior to entering coastal waters, dramatically 

reducing the risk of carrying invasive species” (Pacific Merchant Shipping Agency, National 

Environmental Coalition on Invasive Species, NECIS) . Similarly, an industry led initiative, Marine 

Vessel Environmental Performance (MVeP), provides a numerical score to rate the environmental 

soundness of ballast water management. This score accounts for both the volume and the concentration 

of the ballast water discharged. 

While many of these alternatives are conceptual at this point and may be limited to only specific vessels 

and/or routes, future ballast water management approaches to minimize the risk of invasive species may 

involve a variety of options and combination approaches. Regulatory frameworks for ballast water 

management that address both the volume and concentration of organisms in ballast discharges could 

further facilitate these alternative management approaches. 
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6.5.4. Temporal and Spatial Patterns

Independent of practices of ballast water uptake and total volume of a given discharge (previous 

sections), operational adjustments that modify the temporal and spatial patterns of ballast water 

discharge also may reduce the probability that discharged propagules will found a self-sustaining 

population (Drake et al. 2005). At least for sexually reproducing populations of planktonic species, for a 

given concentration of a given species in ballast discharge, the greater the volume discharged in a given 

time at a given location, the greater the probability of population establishment. If a total discharge 

volume for a given port of call can be broken up in space or time, invasion risk will be lowered. Thus, if 

a given discharge volume can be spread over space (e.g., as a vessel approaches harbor), be 

discontinuous in time (with scheduled breaks in discharge), or be discharged in a mixing environment 

(to dilute the concentration of propagules), the risk of invasion will be lowered (Drake et al. 2005).

For the same reasons, infrastructure modifications within ports that increase the rate and/or magnitude of 

dilution of discharged propagules also would decrease the risk of population establishment by 

discharged propagules. If discharges could be made in or piped to locations of greatest mixing within the 

harbor (e.g., closer to the tidal channels instead of in partially enclosed ship slips), then the rate of 

diffusion would be more likely to overcome the rate of reproduction. For example, low-velocity lowenergy propellers, oloid mixers, or other mixing methods are routinely used in sewage treatment plants, 

industrial applications, and lakes. Such devices could be used in ports to increase the severity of Allee 

effects and other population hurdles faced by newly discharged propagules to minimize the probability 

of population establishment.

6.5.5. Combined Approaches

It may be possible to meet more stringent performance standards, or otherwise reduce the risk of 

invasions from ballast water discharges, by combining the approaches discussed in previous sections 

with either shipboard or onshore treatment. For example, a study by Fisheries and Oceans Canada 

suggests that conducting a mid-ocean exchange combined with BWMS for Great Lakes bound carriers 

may result in at least a 10x reduction in density of high risk taxa (Examining a combination treatment 

strategy: ballast water exchange PLUS treatment, Sarah Bailey, Fisheries and Oceans Canada). After 

considering the best science and technology now available, the state of Wisconsin is proposing to 

continue requiring ships to flush their ballast tanks at sea and require oceangoing ships to use BWMS to 

reduce remaining organisms to a level that meets the international numerical standard. This approach of 

combining ballast water exchange with shipboard ballast water treatment is targeting an enhanced level 

of protection for freshwater environments, similar to what has been proposed by Canada.

Each step from ballasting to deballasting, including the choice of procedures and the choice of 

technologies, contributes to the probability of an invasion occurring (see below). Recognizing and better 

quantifying the probability associated with each step could better target management efforts and achieve 

reductions in the overall probability of invasion at lower cost than relying only on BWMS.
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6.6. Risk Management Approaches to Reduce Invasion Risk: Hazard Analysis and Critical 

Control Points (HAACP)

The Panel provides the following analysis as an example of one potential risk management approach 

that could be applied to ballast water management.

What is HACCP?

Risk assessment for decision-making can be implemented using the Hazard Analysis and Critical 

Control Points (HACCP) approach. HACCP was developed in the late 1950s to assure adequate food 

quality for the nascent NASA program, further developed by the Pillsbury Corporation, and ultimately 

codified by the National Advisory Committee on Microbiological Criteria for Foods in 1997. The 

framework consists of a seven-step sequence:

1) Conduct a hazard analysis.

2) Determine the critical control points (CCPs).

3) Establish critical limit(s).

4) Establish a system to monitor control of the CCPs.

5) Establish the corrective action to be taken when monitoring indicates that a particular CCP is 

not under control.

6) Establish procedures for verification to confirm that the HACCP system is working 

effectively.

7) Establish documentation concerning all procedures and records appropriate to these 

principles and their application.

In international trade, these principles are important parts of the international food safety protection 

system. The development of HACCP ended reliance on the use of testing of the final product as the key 

determinant of quality, and instead emphasized the importance of understanding and control of each step 

in a processing system (Sperber and Stier 2009). HAACP principles also appear applicable to 

operationalize risk management for ballast water.

Basic Definitions

Hazard: The hazard under HACCP is the constituent whose risk one is attempting to control.

Critical control point: A critical control point (defined in the food sector) is "any point in the 

chain of food production from raw materials to finished product where the loss of control could 

result in unacceptable food safety risk"(Unnevehr and Jensen 1996).

Performance criteria: An important task in the HACCP process is to set performance criteria 

(critical limits) at each of the critical control points (CCP). The minimum performance criteria 

for each of the CCPs is set based on the final desired quality These criteria are determined using 

experimentation, computational models or a combination of such methods (Notermans et al. 

1994). Then, readily measurable characteristics for each process needed to assure the desired 

quality are established and coupled to the control points. 
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Application in Food and Water

HACCP has been applied in the food safety area for 50 years, and in the past decade guidelines and 

regulations in the U.S. have been written that require an approved HACCP process in a number of 

applications. For example, the U.S. Food and Drug Administration has developed a HACCP process 

applicable to the fish and shellfish industries (21 CFR 123). HACCP has also been widely adopted in the 

EU, Canada and a number of other developed and developing nations for food safety (Ropkins and Beck

2000).

Havelaar (1994) was one of the first to note that the drinking water supply/treatment and distribution 

chain has a formal analogy to the food supply/processing/transport/sale chain, and therefore that 

HACCP would be applicable. However, in effect, the development of the U.S. surface water treatment 

rule under the Safe Drinking Water Act (40 CFR 141-142) and subsequent amendments incorporate a 

HACCP-like process. Under this framework, an implicitly acceptable level of viruses and protozoa in 

treated water was defined. Based on this, specific processes operated under certain conditions (e.g., filter 

effluent turbidity for granular filters) were “credited” with certain removal efficiencies, and a sufficient 

number of removal credits needed to be in place depending on an initial program of monitoring of the 

microbial quality of the supply itself. This approach (of a regulation by treatment technique) is chosen 

when it is not “economically or technically feasible to set an MCL [maximum contaminant level]” (Safe 

Drinking Water Act section 1412(b)(7)(A)).

How HACCP Might be Applied to Ballast Water Management

Shipboard BWMS and onshore treatment of ballast water differ in a number of characteristics that 

would affect their respective HACCP processes. Implementation of a HACCP program would need to 

account for different regulatory agencies and their scope of enforcement, the training of personnel, and 

the operational factors of each type of treatment. Figure 6-2 illustrates the control points for managing 

ballast water to reduce invasion risk; these are elaborated in the following examples of steps in applying 

the HAACP process: 

• Identify the critical control points (which might include each particular treatment process as 

well as the method and type of intake water used)

• Determine the needed total reduction of organisms needed for the totality of the treatment 

system given the nature of the intake water (to achieve D-2, 10x D-2, etc.), and allocate these 

reductions amongst individual treatment processes.

• Given criteria in the discharged treated ballast water (D-2, 10x D-2, etc.), determine the 

minimum performance criteria for each treatment process, as well as criteria that determine 

whether or not particular intake water might be suitable. Note that these performance criteria 

should be based on easily measurable parameters that can be used for operational control. 

Research may be needed to determine relationships for each process between such surrogate 

parameters and removal of each of the size classes of organisms.

• A given ship having a set of processes with designated removal credits would only be 

allowed to take in ballast water that does not exceed the capacity of the controlled process 

train to meet the discharge criteria under the controlled operation.

• A QA process would be established for periodic validation and auditing (possibly by a thirdparty organization). Operational procedures would need to be developed to indicate the

corrective actions needed for a particular process in the event that surrogate parameters fall 
94

outside acceptable limits, e.g., for additional holding time, recirculating for additional 

treatment, or some other measure.

• A blind testing procedure for the treatment products could be added to ensure that testing 

laboratory is not biased.

• Control points could also be identified for the various steps associated with transfer of an 

invasive species to a new habitat. 

Figure 6-2. Some control points for the control of invasive species. Each of the processes may have imbedded control

points.

The overall context for applying HACCP methods varies depending upon the treatment envisioned. One 

criterion for deciding which option is more straightforward to implement may be the ease with which a 

risk management scheme can be applied and control ensured. In the consideration of shipboard and 

reception facilities, the Panel notes there are uncertainties in both approaches. The Panel has 

recommended that such uncertainties for ballast water treatment be assessed using a risk management 

framework such as HACCP. For this report, none of the BWMS or alternative ballast water approaches 

have been evaluated with respect to the risk of species invasions nor have critical control points been 

identified within the full sequence of ballast water management activities. Given the similarities among 

onshore treatment in reception facilities and water treatment facilities, some preliminary and partial 

extrapolations may be possible. However, the lack of information precludes further analysis of this issue

by the Panel.

Figure 6-2 can be used as a heurist for identifying potential control points. For example, the 

characteristics of the port of origin could be included in the consideration of the types of propagules 

likely to be included in the ballast water. Known hazards from particular ports could be identified and 

the protocol for the control process modified for those ports. Open-ocean (or water) exchange is a way 

to reduce the number of propagules from the original port. Sea conditions or other factors may preclude

an exchange. The control process may require modification to allow for this contingency. Next, there is 

transfer from the ballast tanks to the treatment system, which could be shipboard or on-shore. For either 

treatment, multiple control points could be identified. The role of sea chests, filter systems, oxidizing 

systems and plumbing could be identified. The HACCP approach would also take into account that 

onboard and on-shore treatment facilities will differ in the number and location of discharge points.
95

Likely outside of an engineering-based HACCP, but part of an overall strategy, is the consideration of 

the receiving waters for the ballast water and the types of habitat. Receiving habitats that are similar to 

those of the original port are likely to provide more opportunity for the establishment of an invasive 

species or pathogen. This information may be useful in establishing a site-specific treatment 

recommendation. These habitats could also be monitored as part of an overall plan for reducing the 

likelihood of successful invasion.

HACCP can also be used to set priorities for the implementation of alternative means for managing 

ballast water. Most current BWMS are built with a one-size-fits-all approach and designed to be adopted 

by thousands of ships at some future time. There are defensible reasons for this one-size-fits-all 

approach, but as considered above, additional reasons exist to consider more flexible and combination 

approaches. This is especially true in the face of tight budgets and the constant need to prioritize 

spending on the most cost-effective strategies to reduce invasion risk. Setting priorities using HACCP 

principles could provide a basis for guiding the deployment of combinations of technologies and 

practices now and in the future (Keller et al. 2010). For example, to minimize invasion risk most costeffectively while BWMS are being phased in, the highest risk ships that conduct the highest risk 

voyages could be retrofitted first. Likewise, ship-voyage specific risk assessments could guide the 

schedules for compliance monitoring of the operation and condition of installed water treatment 

systems.

6.7. Summary and Recommendations

6.7.1. Principal Limitations of Available Data and Protocols

• Data are not sufficiently compatible to compare rigorously across ballast water treatment 

systems because accepted standard protocols for testing ballast water treatment systems have 

been lacking, although they have been under development at multiple testing sites. The EPA

ETV Protocol (U.S. EPA 2010) will improve this situation.

• No international requirement exists to report failures in type approval testing. On the basis of 

typically reported results, therefore, it is impossible to draw reliable conclusions about the 

consistency or reliability of some BWMS. 

• The important size class of protists < 10 μm previously has been ignored in developing 

guidelines and standards.

• Clear definitions and direct methods to enumerate viable organisms in the specified size 

classes at low concentrations are missing for some size classes and indicator organisms, and 

logistically problematic for all size classes, especially nonculturable bacteria, viruses, and 

resting stages of many other taxa.

6.7.2. Alternatives to Shipboard Treatment of Ballast Water

• Data on the effectiveness of practices and technologies other than shipboard ballast water 

treatment systems are inadequate because insufficient attention has been given to integrated 

sets of practices and technologies, including: (1) managing ballast uptake to reduce presence 

of invasives, (2) reducing invasion risk from ballast discharge through operational 

adjustments and changes in ship design to reduce or eliminate the need for ballast water, (3) 
96

development of voyage-based risk assessments and/or HACCP principles, and (4) options for 

treatment in reception facilities.

• Use of reception facilities for the treatment of ballast water appears to be technically feasible 

(given generations of successful water treatment and sewage treatment technologies), and is 

likely to be more reliable and more readily adaptable than shipboard treatment. Existing 

regional economic studies suggest that treating ballast water in reception facilities would be 

at least as economically feasible as shipboard treatment. However, these studies consider 

only vessels calling at those regional facilities; if vessels also call at ports outside the region

without reception facilities, they would need a shipboard BWMS12. The effort and cost of 

monitoring and enforcement needed to achieve a given level of compliance is likely to be 

less for a smaller number of reception facilities compared to a larger number of BWMS.

6.7.3. Recommendations to Overcome Present Limitations 

• Testing of BWMS in a research and development mode should be distinct from testing for 

certification, and certification testing should be conducted by a party independent from the 

manufacturer with appropriate established credentials, approved by EPA/USCG.

• Reported results from type approval testing of BWMS should include failures as well as 

successes during testing (as per the Protocol) so that the reliability of systems can be judged. 

This would be aided by the adoption of a transparent international standard format for reporting, 

including specification of QA/QC protocols. 

• Consideration should be given to including protist-sized organisms < 10 μm in dimension in 

ballast water standards, and therefore in protocols to assess the performance of ballast water 

treatment systems.

• Consideration should be given to expanding test protocols recommended by the ETV to 

include components highlighted in Table 6-4. 

• Suitable standard test organisms should be identified for bench-scale testing, and surrogate 

parameters should be investigated to complement or replace metrics that are logistically 

difficult or infeasible for estimating directly the concentration of living organisms. 

• Use of representative “indicator” taxa (toxic strains of Vibrio cholerae; Escherichia coli; 

intestinal Enterococci) should continue as a sound approach to assess BWMS for effective 

removal of harmful bacteria. These estimates will be improved when reliable techniques 

become available to account for active nonculturable cells as well as culturable cells.

• U.S. EPA is urged to develop metrics and methods appropriate for compliance monitoring 

and enforcement as soon as possible.

 12 Dr. Cohen, who read these studies, objected to this sentence as being untrue and misleading and felt that there had not been 

adequate opportunity for Panel discussion of the issue.
97

• Combinations of practices and technologies should be considered as potentially more 

effective approaches than reliance on one ballast water treatment technology. For example, 

ship-specific risk assessments (based on the environment and organisms present in previous 

ports of call) could be used to help prioritize the use of risk management practices and 

technologies, as well to target compliance and enforcement efforts.

• EPA should conduct a comprehensive analysis comparing biological effectiveness, cost, 

logistics, operations, and safety associated with both shipboard BWMS and reception 

facilities. If the analysis indicates that treatment at reception facilities is both economically 

and logistically feasible and is more effective than shipboard treatment systems, then it 

should be used as the basis for assessing the ability of available technologies to remove, kill, 

or inactivate living organisms to meet a given discharge standard. In other words, use of 

reception facilities may enable ballast water discharges to meet a stricter standard.

• Risk management is critical to ensure the efficacy of the entire spectrum of ballast water

management; that is, not just the specific treatment process but also management practices, 

logistics and testing. Hazard Analysis and Critical Control Points (HACCP) has been 

demonstrated to be an effective risk management tool in a variety of situations and could be 

applied to ballast water management. HACCP methods are well understood and flexible. 

HACCP can be used to set priorities for ballast water management and can be applied to 

shipboard or shore-based systems or alternative management measures.

 
R-1

REFERENCES

Agusti, S. and M.C. Sánchez. 2002. Cell viability in natural phytoplankton communities quantified by a 

membrane permeability probe. Limnology and Oceanography 47: 818-828.

Albert, R. and R. Everett. 2010. Capabilities of shipboard ballast water treatment technology. 

Presentation to EPA’s Science Advisory Board, July 29, 2010, Washington, DC.

Albert, R., R. Everett, J. Lishman, and D. Smith. 2010. Availability and Efficacy of Ballast Water 

Treatment Technology: Background and Issue Paper. U.S. EPA and US Coast Guard, Washington, DC.

Available on the SAB website, at 

http://yosemite.epa.gov/sab/sabproduct.nsf/02ad90b136fc21ef85256eba00436459/9E6C799DF254393A

8525762C004E60FF/$File/OW_Paper_Ballast_water_technology_issues_and_background_June_2010.

pdf.

American Bureau of Shipping (ABS). 2010. Ballast Water Treatment Advisory. American Bureau of 

Shipping, Houston, TX. 

American Public Health Association (APHA), American Water Works Association and Water 

Environment Federation. 2008. Standard Methods for the Examination of Water and Wastewater, 21st

edition. APHA, Washington, DC.

Anderson, A.B., B.O. Johannessen, and E. Dragsund. 2004. Ballast water treatment verification protocol 

– DNV. In: Proceedings of the 2nd International Ballast Water Treatment R&D Symposium, by J.T. 

Matheickal and S. Raaymakers (eds.). IMO, London, UK.

Anderson, A., J. Cordell, F. Dobbs, R. Herwig, and A. Rogerson. 2008. Screening of Surrogate Species 

for Ballast Water Treatment. Final Report to NSF International, Ann Arbor, MI.

Aquatic Sciences. 1996. Examination of Aquatic Nuisance Species Introductions to the Great Lakes 

through Commercial Shipping Ballast Water and Assessment of Control Options Phase II. Final Report. 

A Report for the Canadian Coast Guard. Aquatic Sciences Inc., St. Catharines, Ontario, Canada, 60 pp.

Audemard, C., K.C. Rease and E.M. Burreson. 2004. Real-time PCR for detection and quantification of 

the protistan parasite Perkinsus marinus in environmental waters. Applied and Environmental 

Microbiology 70:6611-6618.

Australian Quarantine and Inspection Service (AQIS). 1993a. Ballast Water Treatment for the Removal 

of Marine Organisms. Prepared by Gutheridge, Haskins and Davey Pty Ltd. Ballast Water Research 

Series Report No. 1, AQIS, Canberra, Australia, 106 pp.

Australian Quarantine and Inspection Service (AQIS). 1993b. Ballast Water Management 

Study. Prepared by Thompson Clarke Shipping Pty Ltd. Ballast Water Research Series Report No. 4, 

AQIS, Canberra, Australia, 254 pp.

Avnimelech, Y., B.W. Troeger and L.W. Reed. 1982. Mutual flocculation of algae and clay evidence 

and implications. Science 216:63-65.
R-2

Baldino, R. 1995. Outline of Standard Protocols for Particulate Organic Carbon (POC) Analyses. 

University of Wisconsin - Madison, Madison, WI.

Barcina, I., P. Lebaron, and J. Vives-Rego. 1997. Survival of allochthonous bacteria in aquatic systems: 

a biological approach. FEMS Microbiology Ecology 23:1-9.

Behrens, Y.S. and C. Hunt. 2000. The arrival and spread of the European green crab, Carcinus maenas, 

in the Pacific Northwest. Dreissena: The Digest of National Aquatic Nuisance Species Clearinghouse 

11:1–7.

Binet, M.T. and J.L. Stauber. 2006. Rapid flow cytometric method for the assessment of toxic 

dinoflagellate cyst viability. Marine Environmental Research 62:247-260.

Blenkinsopp, S.A. and M.A. Lock. 1990. The measurement of electron transport system activity in river 

biofilms. Water Research 24:441-445.

Bolch, C.J. and G.M. Hallegraeff. 1993. Chemical and physical treatment options to kill toxic 

dinoflagellate cysts in ships’ ballast water. Journal of Marine and Environmental Engineering 1:23-29.

Bosch, A., F.X. Abad and R.M. Pintó. 2005. Human pathogenic viruses in the marine environment, 

pp.109-131. In: Oceans and Health: Pathogens in the Marine Environment, by S. Belkin and R.R. 

Colwell (eds.). Springer, New York, NY.

Bott, N.J., K.M. Ophel-Keller, M.T. Sierp, Herdina, K.P. Rowling, A.C. McKay, M.G.K. Loo, J.E. 

Tanner, and M.R. Deveney. 2010. Toward routine, DNA-based detection methods for marine pests. 

Biotechnology Advances 28:706-714.

Bowles, N.D., H.W. Pearl, and J. Tucker. 1985. Effective solvents and extraction periods employed in 

phytoplankton carotenoid and chlorophyll determination. Canadian Journal of Fisheries and Aquatic 

Science 42:1127-1131.

Boyer, G.L. 2007. The occurrence of cyanobacterial toxins in New York lakes: Lessons from the 

MERHAB-Lower Great Lakes Program. Lake and Reservoir Management 23:153-60

Boyer, J.N., C.R. Kelbe, P.B. Ortner, and D.T. Rudnick. 2009. Phytoplankton bloom status: Chlorophyll 

a biomass as an indicator of water quality condition in the southern estuaries of Florida, USA. 

Ecological Indicators 9s: s56-s67. 

Bratbak, G., O.H. Haslund, M. Heldal, A. Naess and T. Roeggen. 1992. Giant marine viruses? Marine 

Ecology Progress Series 85:201-202.

Brown & Caldwell. 2007. Port of Milwaukee Onshore Ballast Water Treatment – Feasibility Study 

Report. Prepared for the Wisconsin Department of Natural Resources. Brown & Caldwell, Milwaukee,

WI, 114 pp.

Brown & Caldwell, and Bay Engineering. Inc. 2008. Port of Milwaukee Onshore Ballast Water 

Treatment – Feasibility Study Report. Phase 2. Prepared for the Wisconsin Department of Natural 

Resources. Brown & Caldwell, Milwaukee, WI, 98 pp.
R-3

Brussaard, C.P.D., D. Marie, R. Thyrhaug, and G. Bratbak. 2001. Flow cytometric analysis of 

phytoplankton viability following viral infection. Aquatic Microbial Ecology 26:157-166.

Buchanan, C., R. Lacouture, H.G. Marshall, M. Olson, and J. Johnson. 2005. Phytoplankton reference 

communities for Chesapeake Bay and its tidal tributaries. Estuaries 28:138-159.

Burkholder, J.M. 1992. Phytoplankton and episodic suspended sediment loading: Phosphate partitioning 

and mechanisms for survival. Limnology and Oceanography 37:974-988.

Burkholder, J.M. 1998. Implications of harmful marine microalgae and heterotrophic dinoflagellates in 

management of sustainable marine fisheries. Ecological Applications 8: S37-S62.

Burkholder, J.M. 2009. Harmful algal blooms, pp. 264-285. In: Encyclopedia of Inland Waters, Volume 

1, by G.E. Likens (ed.). Elsevier, Oxford, UK.

Burkholder, J.M. and P.M. Gilbert. 2006. Intraspecific variability: An important consideration in 

forming generalizations about toxigenic algal species. South African Journal of Marine Science 28:177-

180.

Burkholder, J.M., A.S. Gordon, P.D. Moeller, J.M. Law, K.J. Coyne, A.J. Lewitus, J.S. Ramsdell H.G. 

Marshall, N.J. Deamer, S.C. Cary, J.W. Kempton, S.L. Morton, and P.A. Rublee. 2005. Demonstration 

of toxicity to fish and to mammalian cells by Pfiesteria species: Comparison of assay methods and 

multiple strains. Proceedings of the National Academy of Sciences (U.S.A) 102: 3471-3476.

Burkholder, J.M., G.M. Hallegraeff, G. Melia, A. Cohen, H.A. Bowers, D.W. Oldach, M.W. Parrow, 

M.J. Sullivan, P.V. Zimba, E.H. Allen, and M.A. Mallin. 2007. Phytoplankton and bacterial assemblages 

in ballast water of U.S. military ships as a function of port of origin, voyage time and ocean exchange 

practices. Harmful Algae 6: 486-518.

California Association of Port Authorities (CAPA). 2000. Feasibility of Onshore Ballast Water 

Treatment at California Ports. Prepared by URS Corporation/Dames & Moore. CAPA, Sacramento, 

CA. 

California State Lands Commission (SLC). 2009. Assessment of the Efficacy, Availability and 

Environmental Impacts of Ballast Water Treatment Systems for Use in California Waters. California 

SLC, Sacramento, CA, 180 pp.

California State Lands Commission (SLC). 2010. 2010 Assessment of the Efficacy, Availability and 

Environmental Impacts of Ballast Water Treatment Systems for Use in California Waters. CSLC, 

Sacramento, CA, 141 pp.

California State Water Resources Control Board (SWRCB). 2002. Evaluation of Ballast Water 

Treatment Technology for Control of Nonindigenous Aquatic Organisms. SWRCB, California 

Environmental Protection Agency, Sacramento, CA, 70 pp.

Cangelosi, A.A., N.L. Mays, M.D. Balcer, E.D. Reavie, D.M. Reid, R. Sturtevant, and X. Gao. 2007. 

The response of zooplankton and phytoplankton from the North American Great Lakes to filtration. 

Harmful Algae 6: 547-566.
R-4

Carlton, J.T., D.M. Reid and H. van Leeuwen. 1995. Shipping Study. The Role of Shipping in the 

Introduction of Nonindigenous Aquatic Organisms to the Coastal Waters of the United States (other 

than the Great Lakes) and an Analysis of Control Options. Report No. CG-D-11-95, U. S. Coast Guard, 

Groton CT and U. S. Dept. of Transportation, Washington DC.

Caron, D.A., P.D. Countway and M.V. Brown. 2004. The growing contributions of molecular biology 

and immunology to protistan ecology: Molecular signatures as ecological tools. Journal of Eukaryotic 

Microbiology 51:38-48.

Cohen, A.N. 1998. Ships' Ballast Water and the Introduction of Exotic Organisms into the San 

Francisco Estuary: Current Status of the Problem and Options for Management. A report for the 

Collaboration Among State and Federal Agencies to Improve California’s Water Supply (CALFED) and 

the California Urban Water Agencies. San Francisco Estuary Institute, Richmond, CA.

Cohen, A.N. and B. Foster. 2000. The regulation of biological pollution: Preventing exotic species 

invasions from ballast water discharged into California coastal waters. Golden Gate University Law 

Review30: 787-883.

Colnar, A.M. and W.G. Landis. 2007. Conceptual model development for invasive species and a 

regional risk assessment case study: the European Green Crab, Carcinus maenas, at Cherry Point, 

Washington USA. Human and Ecological Risk Assessment 13:120-155.

Connelly, S.J., E.A. Wolyniak, K.L. Dieter, C.E. Williamson, and K.L. Jellison. 2007. Impact of 

zooplankton grazing on the excystation, viability, and infectivity of the protozoan pathogens 

Cryptosporidium parvum and Giardia lamblia. Applied and Environmental Microbiology 73:7277-7282.

Cromeans, T., J. Narayanan, K. Jung, G. Ko, D. Wait, and M. Sobsey. 2005. Development of Molecular 

Methods to Detect Infections Viruses in Water. American Water Works Association Research 

Foundation Report 90995F. ISBN 9781843398912, 128 pp.

Cuker, B.E. and L. Hudson Jr. 1992. Type of suspended clay influences zooplankton response to 

phosphorus loading. Limnology and Oceanography 37:566-576.

Dames & Moore. 1998. Ballast water management technical memorandum for the Port of Oakland. Job 

No. 02801-028-086, November 6, 1998. Dames & Moore, San Francisco, CA.

Dames & Moore. 1999. Phase I Final Report Ballast Water Exchange and Treatment. A Report for the 

California Association of Port Authorities, Pacific Merchant Shipping Association, Steamship 

Association of Southern California, and Western States Petroleum Association. Dames & Moore, San 

Francisco, CA.

Darzynkiewicz, Z., X. Li and J. Gong. 1994. Assays of cell viability: Discrimination of cells dying by 

apoptosis. In: Methods in Cell Biology, by Z. Darzynkiewicz, J.P. Robinson, and H.A. Crissman (eds.). 

Academic Press, New York.

Deines, A.M., V. Chen and W.G. Landis. 2005. Modeling the risks of non-indigenous species 

introductions using a patch-dynamics approach incorporating contaminant effects as a disturbance. Risk 

Analysis 6:1637-1651.
R-5

Drake, J.M. 2004. Allee Effects and the Risk of Biological Invasion. Risk Analysis 24:795-802.

Drake, J.M. 2005. Risk Analysis For Invasive Species And Emerging Infectious Diseases: Concepts 

And Applications. Am. Midl. Nat. 153:4–19.

Dobbs, F.C. and A. Rogerson. 2005. Ridding ships’ ballast water of microorganisms. Environmental 

Science and Technology 39: 259A-264A.

Doblin, M.A. and F.C. Dobbs (2006) Setting a size-exclusion limit to remove toxic dinoflagellate cysts 

in ships’ ballast water. Marine Pollution Bulletin 52:259-263.

Dobroski, N., C. Scianni, D. Gehringer, and M. Falkner. 2009. 2009 Assessment of the Efficacy, 

Availability and Environmental Impacts of Ballast Water Treatment Systems for Use in California 

Waters. Produced for the California State Legislature. Available at: 

http://www.slc.ca.gov/spec_pub/mfd/ballast_water/documents/2009cslctechreportfinal.pdf.

Dobroski, N., Scianni, C., Takata, L., & Falkner, M. 2009. October 2009 update: Ballast water treatment 

technologies for use in California waters. California State Lands Commission, Marine Invasive Species 

Program. Produced for the California State Legislature. Final Report available at: 

http://www.slc.ca.gov/Spec_Pub/MFD/Ballast_Water/Reports_Presentations.html.

Drake, J.M. and D.M. Lodge. 2006. Allee effects, propagule pressure and the probability of 

establishment: risk analysis for biological invasions. Biological Invasions 8:365–375.

Drake, J.M., D.M. Lodge and M. Lewis. 2005. Theory and preliminary analysis of species invasions 

from ballast water: controlling discharge volume and location. American Midland Naturalist 154: 459-

470.

Elliot, J.M. 1971. Some Methods for the Statistical Analysis of Samples of Benthic Invertebrates. 

Scientific Publication No. 25, Freshwater Biological Association, Windermere, UK.

Fout, G.S., F.W. Schaefer III, J. W. Messer, D.R. Dahling and R.E. Stetler. 1996. ICR Microbial 

Laboratory Manual. U.S. Environmental Protection Agency, Washington, DC.

Garvey, M., B. Moriceau and U. Passow. 2007. Applicability of the FDA assay to determine the 

viability of marine phytoplankton under different environmental conditions. Marine Ecology Progress 

Series 352: 17-26.

Gauthier, D. and D.A. Steel. 1996. A Synopsis of the Situation Regarding the Introduction of 

Nonindigenous Species by Ship-Transporting Ballast Water in Canada and Selected Countries. 

Canadian Manuscript Report of Fisheries and Aquatic Sciences No. 2380. Marine Environmental 

Sciences Division, Department of Fisheries and Oceans, Maurice Lamontagne Institute, Mont-Joli 

(Quebec), Canada.

Glosten Associates.2002. Pacific Ballast Water Treatment Pilot Project: Ballast Water Transfer Study: 

Technical Feasibility with Associated Capital Costs. Report prepared for the Port of Seattle, Seattle, 

WA. File No. 01080. Glosten Associates, Seattle, WA, 36 pp.
R-6

Great Ships Initiative. 2010. Report of the Land-Based Freshwater Testing by the Great Ships Initiative 

of the Siemens SiCURETM Ballast Water Management System for Type Approval According to 

Regulation D-2 and the Relevant IMO Guidelines. Great Ships Initiative. 

http://www.nemw.org/GSI/GSI-LB-F-A-1.pdf.

Gregg, M.D. and G.M. Hallegraeff. 2007. Efficacy of three commercially available ballast water 

biocides against vegetative microalgae, dinoflagellate cysts and bacteria. Harmful Algae 6:567-584.

Griffin, D.W., K.A. Donaldson, J.H. Paul and J.B. Rose. 2003. Pathogenic human viruses in coastal 

waters. Clinical Microbiology Reviews 16:129–143.

Guy, R.A., P. Payment, U.J. Krull and P.A. Horgen. 2003. Real-time PCR for quantification of Giardia

and Cryptosporidium in environmental water samples and sewage. Applied and Environmental 

Microbiology 69:5178-5185.

Hallegraeff, G.M. and C.J. Bolch. 1991. Transport of toxic dinoflagellate cysts via ships’ ballast water. 

Marine Pollution Bulletin 22: 27-30.

Hallegraeff, G.M. and C.J. Bolch. 1992. Transport of dinoflagellate cysts in ship’s ballast water: 

Implications for plankton biogeography and aquaculture. Journal of Plankton Research 14:1067-1084.

Hallegraeff, G.M., J.P. Valentine, J.-A. Marshall and C.J. Bolch. 1997. Temperature tolerances of toxic 

dinoflagellate cysts: application to the treatment of ships’ ballast water. Aquatic Ecology 31:47-52.

Hampel, M., I. Moreno-Garrido, C. Sobrino, H.L.M. Lubia and J. Blasco. 2001. Acute toxicity of LAS 

homologues in marine microalgae: Esterase activity and inhibition growth as endpoints of toxicity. 

Ecotoxicology and Environmental Safety 48:287-292.

Havelaar, A.H. 1994. Application of HACCP to Drinking Water Supply. Food Control 5(3):145-152.

Hendry, G.A.F., J.D. Houghton and S.B. Brown. 1987. The degradation of chlorophyll - a biological 

enigma. New Phytologist 107: 255-302.

Hoff, R.M., W.M.J. Strachan, C.W. Sweet, C.H. Chan, M. Shackleton, T.F. Bidleman, K.A. Brice, D.A. 

Burniston, S. Cussion, D.F. Gatz, K. Harlin, and W.H. Schroeder (1996) Atmospheric deposition of 

toxic chemicals to the Great Lakes: A review of data through 1994. Atmospheric Environment 30:3505-

3527.

Holm-Hansen, O. 1973. The use of ATP determinations in ecological studies. Bulletin of the Ecological 

Research Commission (Stockholm) 17:215-222.

Howard, G., J. Bartram, S. Pedley, O. Schmoll, I. Chorus and P. Berger. 2006. Groundwater and public 

health, pp. 3-19. In: Protecting Groundwater for Health: Managing the Quality of Drinking-Water 

Sources, byO. Schmoll, G. Howard, J. Chilton, and I. Chorus (eds.). IWA Publishing, London, U.K.

Hunt, C.D., D.C. Tanis, T.G. Stevens, R.M. Frederick and R.A. Everett. 2005 (August 1). Verifying 

ballast water treatment performance. Environmental Science and Technology 321A-328A.
R-7

International Maritime Organization (IMO). 2004. International Convention for the Control and 

Management of Ships' Ballast Water and Sediments, 2004. IMO, International Conference on Ballast 

Water Management for Ships.

International Maritime Organization (IMO). 2005a. Guidelines tor Ballast Water Management 

Equivalent Compliance (G3). IMO, Marine Environment Protection Committee, Resolution MEPC 

123(53), adopted 22 July 2005.

International Maritime Organization (IMO). 2005b. Guidelines for Ballast Water Management and 

Development of Ballast Water Management Plans (G4). IMO, Marine Environment Protection 

Committee (MEPC), Resolution MEPC 127(53), adopted 22 July 2005.

International Maritime Organization (IMO). 2008a. Guidelines for Approval of Ballast Water 

Management Systems (G8). Marine Environment Protection Committee (MEPC), Annex 4 Resolution 

MEPC.174(58). Available at: 

http://www.regulations.gov/search/Regs/home.html#documentDetail?R=09000064807e8904. 

International Maritime Organization (IMO). 2008b. Procedure for Approval of Ballast Water 

Management Systems that Make Use of Active Substances (G9). Marine Environment Protection 

Committee (MEPC), Annex 1 Resolution MEPC.169(57). Available at: 

http://www.regulations.gov/search/Regs/home.html#documentDetail?R=09000064807e890e. 

Inubushi, K., P.C. Brookes and D.S. Jenkinson. 1989. Adenosine 5’-triphosphate and adenylates energy 

charge in waterlogged soil. Soil Biology and Biochemistry 21:733-739.

Jeffrey, S.W. and M. Vest. 1997. Introduction to marine phytoplankton and their pigment signatures, pp. 

37-87. In: Phytoplankton Pigments in Oceanography, by S.W. Jeffrey, R.F.C. Mantoura, and S.W. 

Wright (eds.). The United Nations Educational, Scientific, and Cultural Organization (UNESCO), Paris, 

France.

Jeffrey, S., R. Mantoura and S. Wright (eds.). 1997. Phytoplankton Pigments in Oceanography: 

Guidelines to Modern Methods. UN Educational, Scientific & Cultural Organization, Paris, France.

Johnson, W.S. and D.M. Allen. 2005. Zooplankton of the Atlantic and Gulf Coasts – A Guide to Their 

Identification and Ecology. John Hopkins University Press, Baltimore, MD.

Jones, W.J., C.M. Preston, R. Marin III, C.A. Scholin and R.C. Vrijenhoek. 2008. A robotic molecular 

method for in situ detection of marine invertebrate larvae. Molecular Ecology Resources 8:540-550.

Kaneshiro, E.S., M.A. Wyder, Y.-P. Wu, and M.T. Cushion. 1993. Reliability of calceinacetoxy methyl 

ester and ethidiumhomodimer or propidium iodide for viability assessment of microbes. Journal of 

Microbiological Methods 17:1-16.

Karl, D.M. 1980. Cellular nucleotide measurements and applications in microbial ecology. 

Microbiological Reviews 44:739-796.
R-8

Karlson, B., C. Cusack and E. Bresnan. 2010. Microscopic and Molecular Methods for Quantitative 

Phytoplankton Analysis. Intergovernmental Oceanographic Commission (IOC) Manuals and Guides 

#55. IOC, United Nations Educational, Scientific and Cultural Organization, Paris, France, 114 pp.

Kay, S.H. 1985. Cadmium in aquatic food webs. Residue Reviews 96:13-43.

Keller, R.P., J.M. Drake, M.B. Drew and D.M. Lodge. 2010. Linking environmental conditions and ship 

movements to estimate invasive species transport across the global shipping network. Diversity and 

Distributions DOI: 10.1111/j.1472-4642/2010/00696x

Kieft, T.L. and L.L. Rosaker. 1991. Application of respiration and adenylates-based soil microbiological 

assays to deep subsurface terrestrial sediments. Soil Biology and Biochemistry 23:563-568.

King, D.M. and M.N. Tamburri. 2010. Verifying compliance with ballast water discharge regulations. 

Ocean Development & International Law 41:152-165.

Kokinos, J.K., T.I. Eglington, M.A. Goni, J.J. Boon, P.A. Martoglio and D.M. Anderson. 1998. 

Characterization of a highly resistant biomacromolecular material in the cell wall of a marine 

dinoflagellate resting cyst. Organic Geochemistry 28:265-288.

Kolar, C.S. 2004. Risk assessment and screening for potentially invasive species. New Zeal J Mar Fresh

38:391–7.

Kolar, C.S. and D.M. Lodge. 2001. Progress in invasion biology: predicting invaders. Trends Ecol Evol

16:199–204.

Kolar, C.S. and D.M. Lodge. 2002. Ecological predictions and risk assessment for alien species. Science

298:1233–6.

Kotinis, M., M. G. Parsons, T. Lamb and A. Sirviente. 2004. Development and investigation of the 

ballast-free ship concept. Transactions Society of Naval Architects and Marine Engineers 112.

Kudela, R.M., M.D.A. Howard, B.D. Jenkins, P.E. Miller and G.J. Smith. 2010. Using the molecular 

toolbox to compare harmful algal blooms in upwelling systems. Progress in Oceanography 85:108-121.

Laabir, M. and P. Gentien. 1999. Survival of toxic dinoflagellates after gut passage in the Pacific oyster 

CrassostreagigasThunberg. Journal of Shellfish Research 18: 217-222.

Landis, W.G. 2004. Ecological risk assessment conceptual model formulation for nonindigenous 

species. Risk Analysis 24:847-858.

LeChevallier, M.W. and K.K. Au. 2004. Water Treatment and Pathogen Control; Process Efficiency in 

Achieving Safe Drinking Water. World Health Organization, Geneva. IWA Pubishing, London.

Lee II, H., D.A. Reusser, M. Frazier and G. Ruiz. 2010. Density matters: Review of approaches to 

setting organism-based discharge standards. U.S. EPA, Office of Research and Development, National 

Health and Environmental Effects Research Laboratory, Western Ecology Division, Washington, DC.

EPA/600/R-10/031.
R-9

Lemieux, E.J., S. Robbins, K. Burns, S. Ratcliff, and P. Herring. 2008. Evaluation of Representative 

Sampling for Rare Populations using Microbeads. Report No. CG-D-03-09, United States Coast Guard 

Research and Development Center, Groton, CT. 

Lemieux, E.J., L.A. Drake, S.C. Riley, E.C. Schrack, W.B. Hyland, J.F. Grant and C.S. Moser. 2010. 

Design and Preliminary Use of a Commercial Filter Skid to Capture Organisms ≥ 50 μm in Minimum 

Dimension (Nominally Zooplankton) for Evaluating Ships’ Ballast Water Management Systems at LandBased Test Facilities. Report 6130/1029. Center for Corrosion Science and Engineering, Naval Research 

Laboratory, Washington, DC, 41 pp.

Lloyd’s Register. 2010. Ballast Water Treatment Technology: Current Status. Lloyd’s Register, London.

Loganathan, B.G. and K. Kannan. 1994. Global organochlorine contamination trends: an overview. 

Ambio 23:187-191.

Lund, J.W.G., C. Kipling and E.D. LeCren. 1958. The inverted microscope method for estimating algal 

numbers and the statistical basis of estimations by counting. Hydrobiologia 11:143-170.

MacIsaac, E.A. and J.G. Stockner. 1993. Enumeration of phototrophic picoplankton by autofluorescence 

microscopy, pp. 187-198. In: Handbook of Methods in Aquatic Microbial Ecology, by P.F. Kemp, B.F. 

Sherr, E.B. Sherr, and J.J. Cole (eds.). Lewis Publishers, CRC Press, Inc., Boca Raton, FL.

Mackey, M.D., D.J. Mackey, H.W. Higgins and S.W. Wright. 1996. CHEMTAX – A program for 

estimating class abundances from chemical markers: Application to HPLC measurements of 

phytoplankton. Marine Ecology Progress Series 144:265-283.

Madigan, M.T. and J.M. Martinko. 2006. Biology of Microorganisms, 11th ed. Pearson Prentice Hall, 

Upper Saddle River, NJ, p. G-14.

Maier, R.M., I.L. Pepper, and C.P. Gerba (eds.). Environmental Microbiology. Elsevier, New York, NY.

MARAD. Feb. 2011. U.S. Water Transport Statistical Snapshot. US DOT Maritime Administration. 

http://www.marad.dot.gov/library_landing_page/data_and_statistics/Data_and_Statistics.htm

Marine Environment Protection Committee (MEPC). 2006a (21 April). Harmful Aquatic Organisms in 

Ballast Water - Basic Approval of Active Substances Used by Pure Ballast Management System. 

International Maritime Organization, 55th session, Agenda Item 2, MEPC 55/2/5, International Maritime 

Organization.

Marine Environment Protection Committee (MEPC). 2006b (28 Feb.). 54th Session, Agenda item 2 –

Harmful Aquatic Organisms in Ballast Water – Report of the first meeting of the Group of Experts on 

the Scientific Aspects of Marine Environmental Protection Border-Wide Workgroup (GESAMPBWWG). MEPC 54/2/12, International Maritime Organization.

Maritime Environmental Resource Center (MERC). 2009c. Test Plan for the Performance Evaluation of 

the Severn Trent De NoraBalPureTM BP-2000 Ballast Water Management System. Chesapeake 

Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD.
R-10

Maritime Environmental Resource Center (MERC). 2009a. Land-Based Evaluations of the Maritime 

Solutions, Inc. Ballast Water Treatment System. MERC ER02-09, [UMCES] CBL 09-138.

Maritime Environmental Resource Center (MERC). 2009b. M/V Cape Washington Ballast Water 

Treatment Test Facility Validation. Chesapeake Biological Laboratory, University of Maryland Center 

for Environmental Science, Solomons, MD.

Maritime Environmental Resource Center (MERC). 2010a. Land-Based Evaluations of the Siemens 

Water Technologies SiCURE Ballast Water Management System. MERC ER02-10, [UMCES] CBL 10-

038.

Maritime Environmental Resource Center (MERC). 2010b. Land-Based Evaluations of the Severn Trent 

De Nora BalPure BP-1000 Ballast Water Management System. MERC ER01-10, [UMCES] CBL 10-

015.

Marret, F. and K.A.F. Zonneveld. 2003. Atlas of modern organic-walled dinoflagellate cyst distribution. 

Review of Palaeobotany and Palynology 125:1-200.

Matsuoka, K. and Y. Fukuyo. 2000. Technical Guide for Modern Dinoflagellate Cyst Study. Available 

at: http://dinos.anesc.u-tokyo.ac.jp/technical_guide/main.pdf.

Miller, A.W., M. Frazier, G.E. Smith, E.S. Perry, G.M. Ruiz and M.N. Tamburri. 2011. Enumerating 

Sparse Organisms in Ships’ Ballast Water: Why Counting to 10 is Difficult? Environmental Science and 

Technology 45:3539–3546.

Minton, M.S., E. Verling, A.W. Miller and G.M. Ruiz. 2005. Reducing propagule supply and coastal 

invasions via ships: effects of emerging strategies. Frontiers in Ecology and the Environment 3: 304-

308.

Moeller, P.D.R., S.L. Morton, B.A. Mitchell, S.K. Sivertsen, E.R. Fairey, T.M. Mikulski, H.B. Glasgow, 

N.J. Deamer-Melia, J.M. Burkholder and J.S. Ramsdell. 2001. Current progress in isolation and 

characterization of toxins isolated from Pfiesteria spp. Environmental Health Perspectives 109:739-743.

Montresor, M., L. Nuzzo and M.G. Mazzocchi. 2003. Viability of dinoflagellate cysts after the passage 

through the copepod gut. Journal of Experimental Marine Biology and Ecology 287:209-221.

Mosher, J.J., B.S. Levison, and C.G. Johnston. 2003. A simplified dehydrogenase enzyme assay in 

contaminated sediment using 2-(p-iodophenyl)-3(p-nitrophenyl)-5-phenyl tetrazolium chloride. Journal 

of Microbiological Methods 53:411-415.

Munn, C.B. 2006. Viruses as pathogens of marine organisms – from bacteria to whales. Journal of the 

Marine Biological Association of the UK 86:453–467.

Murphy, K.R., D. Ritz, and C.L. Hewitt. 2002. Heterogeneous zooplankton distribution in a ship’s 

ballast tanks. Journal of Plankton Research 24:729-734.

Myers, G.J. 1979. The Art of Software Testing. John Wiley & Sons, New York, NY, pp. 12-13,128.
R-11

National Environmental Coalition on Invasive Species (NECIS). July 2008. New Ballast Tank 

Legislation. http://www.pollutionengineering.com/Articles/Feature_Article/BNP_GUID_9-5-

2006_A_10000000000000380477

National Environmental Services Center (NESC). 2000a. Slow Sand Filtration. Tech Brief: A National 

Drinking Water Clearinghouse Fact Sheet. National Environmental Services Center, West Virginia 

University. Morgantown, WV.

National Environmental Services Center (NESC). 2000b. Ultraviolet Disinfection. Tech Brief: A 

National Drinking Water Clearinghouse Fact Sheet. National Environmental Services Center, West 

Virginia University. Morgantown, WV.

National Research Council (NRC) Marine Board. 1996. Stemming the Tide: Controlling Introductions 

of Nonindigenous Species by Ships' Ballast Water. Committee on Ships' Ballast Operations, Marine 

Board, Commission on Engineering and Technical Systems, NRC. National Academy Press, 

Washington, D.C.

Nelson, B.N., E.J. Lemieux, L. Drake, D. Anderson, D. Kulis, K. Burns, D. Anderson, N. Welschmeyer, 

S. Smith, C. Scianni C, T. Weir, S. Riley and P. Herring. 2009. Phytoplankton Enumeration and 

Evaluation Experiments. Report No. CG-D-06-09, United States Coast Guard Research & Development 

Center, Groton, CT.

Notermans, S., G. Gallhoff, M.H. Zweitering and G.C. Mead. 1994. The HACCP concept: 

Identification of potentially hazardous micro-organisms. Food Microbiology II:203-214. 

Oemke, D. 1999. The Treatment of Ships' Ballast Water. EcoPorts Monograph Series No. 18, Ports 

Corporation of Queensland, Brisbane, Australia, 102 pp.

Ogilvie, D.J. 1995. Land-based treatment options. Pages 113-123 in: Ballast Water. A Marine Cocktail 

on the Move. Proceedings of the National Symposium, 27-29 June 1995, Wellington, New Zealand. The 

Royal Society of New Zealand. Miscellaneous Series 30.

Oliver, J.D. 1993. Formation of viable but nonculturable cells, pp. 239-272. In: Starvation in Bacteria, 

by S. Kjelleberg (ed.). Plenum Press, New York, NY.

Oudot C., R. Gerard, P. Morin and I. Gningue. 1988. Precise shipboard determination of dissolved 

oxygen (Winkler procedure) for productivity studies with a commercial system. Limnology and 

Oceanography 33:146-150.

Parshionikar, S., I. Laseke and G.S. Fout. 2010. Use of propidiummonoazide in reverse transcriptase 

PCR to distinguish between infectious and noninfectious enteric viruses in water samples. Applied and 

Environmental Microbiology 76:4318-4326.

Parsons, M. G. 2010. The Variable Buoyancy Ship: A Road to the Elimination of Ballast. Proceedings 

from IMO and World Maritime University Research and Development Forum: Emerging Ballast Water 

Management Systems, January 26-29, Malmo, Sweden.
R-12

Parsons, M.G. 1998. Flow-through ballast water exchange. Society of Naval Architects and Marine 

Engineers (NAME) Transactions 106:485-493. 

Pate, A.S., A.E. De Souza and D.R.G. Farrow. 1992. Agricultural Pesticide Use in Coastal Areas: A 

National Summary. NOAA, Rockville, MD.

Peal, D.B. 1975. Phthalate Esters: Occurrence and Biological Effects. Springer-Verlag, New York, NY, 

1-41.

Phillips, S. 2006. Ballast Water Issue Paper. Report for the Pacific States Marine Fisheries Commission. 

Portland, OR. 34 pp. (http://www.aquaticnuisance.org/wordpress/wpcontent/uploads/2009/01/ballast_water_issue_paper.pdf).

Pollutech. 1992. A Review and Evaluation of Ballast Water Management and Treatment Options to 

Reduce the Potential for the Introduction of Non-native Species to the Great Lakes. 

Pollutech Environmental, Ltd., Sarnia, Ontario, prepared for the Canadian Coast Guard, Ship Safety 

Branch, Ottawa, Canada.

Porra, R.J. 1991. Recent advances and re-assessments in chlorophyll extraction and assay procedures for 

terrestrial, aquatic, and marine organisms, including recalcitrant algae, pp. 31-57. In: Chlorophylls, by 

H. Scheer (ed.). CRC Press, Boca Raton, FL.

Porter, J., J. Diaper, C. Edwards, and R. Pickup. 1995. Direct measurements of natural planktonic 

bacterial community viability by flow cytometry. Applied and Environmental Microbiology 61: 2783-

2786.

Posch, T., J. Pernthaler, A. Alfreider and R. Psenner. 1997. Cell-specific respiratory activity of aquatic 

bacteria studied with the tetrazolium reduction method, cyto-clear slides, and image analysis. Applied 

and Environmental Microbiology 63:867-873.

Reavie, E.D., A.A. Cangelosi and L.E. Allinger. 2010. Assessing ballast water treatments: Evaluation of 

viability methods for ambient freshwater microplankton assemblages. Journal of Great Lakes Research

36: 540-547.

Reeves, E. 1998. Protection of the Great Lakes from Infection by Exotic Organisms in Ballast Water. 

Report for Ninth US Coast Guard District, Cleveland OH.

Reeves, E. 1999. Exotic Policy: An IJC White Paper On Policies for the Prevention of the Invasion of 

the Great Lakes by Exotic Organisms. Documents on Water Law, College of Law, University of 

Nebraska - Lincoln. 132 pages.

Rigby, G. and A.H. Taylor. 2001a. Ballast Water Treatment to Minimize the Risks of Introducing 

Nonindigenous Marine Organisms into Australian Ports. Ballast Water Research Series Report No. 13, 

Australian Government Department of Agriculture, Fisheries, and Forestry, Canberra, Australia, 93 pp.

Rigby, G. and A. Taylor. 2001b. Ballast water management and treatment options. Transactions of the 

Institute of Marine Engineers 113: 79-99.
R-13

Romano, G., A. Ianora, L. Santella, and A. Miralto. 1996. Respiratory metabolism during embryonic 

subitaneous and diapause development in Pontellamediterranea (Crustacea, Copepoda). Journal of 

Comparative Physiology 166: 157-163.

Ropkins, K. and A. J. Beck. 2000. Evaluation of worldwide approaches to the use of HACCP to control 

food safety. Trends in Food Science & Technology 11(1):10-21.

Rosacker, L.L. and T. L. Kieft. 1990. Biomass and adenylate energy charge of a grassland soil during 

drying. Soil Biology and Biochemistry 22:1121-1127.

Ruiz, G.M., G.E. Smith, and M. Sytsma. 2006. Workshop Report on Testing of Ballast Water Treatment 

Systems: General Guidelines and Step-wise Strategy Toward Shipboard Testing. Aquatic Bioinvasion 

Research and Policy Institute, a joint program of the Smithsonian Environmental Research Center 

(SERC) and Portland State University (PSU). Submitted to the Pacific States Marine Fisheries 

Commission, Alaska Department of Fish and Game, and Prince William Sound Regional Citizens 

Advisory Council, Anchorage, AK.

Sandrin, T.R., D.C. Herman, and R.M. Maier. 2009. Physiological methods, pp. 191-223. In: 

Environmental Microbiology, by R.M. Maier, I.L. Pepper, and C.P. Gerba (eds.). Elsevier, New York, 

NY.

Sarmento, H. and J.-P. Descy. 2008. Use of marker pigments and functional groups for assessing the 

status of phytoplankton assemblages in lakes. Journal of Applied Phycology 20:1001-1011.

Schlüter, L., T.L. Lauridsen, G. Krogh and T. Jørgense. 2006. Identification and quantification of 

phytoplankton groups in lakes using new pigment ratios - a comparison between pigment analysis by 

HPLC and microscopy. Freshwater Biology 51:1474-1485.

Schmid, H., F. Bauer and H.B. Stich. 1998. Determination of algal biomass with HPLC pigment 

analysis from lakes of different trophic state in comparison to microscopically measured biomass. 

Journal of Plankton Research 20:1651-1661.

Shaw, S. and K. Kurunthachalam. 2009. Polybrominateddiphenyl ethers in marine ecosystems of the 

American continents: Foresight from current knowledge. Reviews on Environmental Health 24:157-229. 

Songster-Alpin, M.S. and R.L. Klotz. 1995. A comparison of electron transport system activity in stream 

and beaver pond sediments. Canadian Journal of Fisheries and Aquatic Sciences 52:1318-1326.

Sperber, W. H. and R. F. Stier. 2009. Happy 50th Birthday to HACCP: Retrospective and Prospective. 

foodsafetymagazine.com (December 2009).

Steinberg, M.K., M.R. First, E.J. Lemieux, L.A. Drake, B.N. Nelson, D. Kulis, D. Anderson, N. 

Welschmeyer, and P. Herring (accepted with revisions) Comparison of techniques used to count singlecelled viable phytoplankton. Journal of Applied Phycology.
R-14

Steinberg, M.K., S.C. Riley, S.H. Robbins, B.N. Nelson, E.J. Lemieux and L.A. Drake. 2010. Multi-site 

validation of a method to determine the viability of organisms ≥ 10 μm and < 50 μm (nominally protists) 

in ships’ ballast water using two vital, fluorescent stains. NRL Letter Report 6130/1016, Washington, 

DC.

Stevens, T.G., R.M. Frederick, R.A. Everett, J.T. Hurley, C.D. Hunt and D.C. Tanis. 2004. Performance 

verification of ballast water treatment technologies by USEPA/NSF Environmental Technology 

Verification Program. In: Proceedings of the 2nd International Ballast Water Treatment R&D 

Symposium, by J.T. Matheickal and S. Raaymakers (eds.). IMO, London, UK.

Suban, V., P. Vidmar and M. Perkovic, 2010. Ballast Water Replacement with Fresh Water – Why Not? 

Proceedings from IMO and World Maritime University Research and Development Forum: Emerging 

Ballast Water Management Systems, January 26-29, Malmo, Sweden.

Sugita, H., T. Mitsaya, K. Amanuma, K. Hayashi, T. Asai, C. Maruyama and Y. Degechi. 1992. 

Ultraviolet susceptibility of three marine fish pathogens. Bulletin of the College of Agriculture and 

Veterinary Medicine 49:117-121.

Suttle, C.A. 2007. Marine viruses - major players in the global ecosystem. Nature Reviews -

Microbiology 5:801-812.

Suttle, C.A., A.M. Chan and M.T. Cottrell. 1991. Use of ultrafiltration to isolate viruses from seawater 

which are pathogens of marine phytoplankton. Applied and Environmental Microbiology 57:721-726.

Takano, C.T., C.E. Folsome, and D.M. Karl. 1983. ATP as a biomass indicator for closed ecosystems. 

BioSystems 44:739-796.

Taylor, L.R. 1961. Aggregation, variance and the mean. Nature 189:732-735.

Turner, R.E. 1978. Variability of the reverse-flow concentration technique of measuring plankton 

respiration. Estuaries 1:65-68.

United States Coast Guard. 1999. Implementation of the National Invasive Species Act of 1996 (NISA). 

Interim rule. U.S. Federal Register 64(94): 26672-26690 (May 17, 1999).

United States Coast Guard. 2001a. Implementation of the National Invasive Species Act of 1996 

(NISA). Final rule. U.S. Federal Register 66(225): 58381-58393 (November 21, 2001).

United States Coast Guard. 2001b. Report to Congress on the Voluntary National Guidelines for Ballast 

Water Management. Washington D.C.

United States Coast Guard. 2002. Standards for Living Organisms in Ship's Ballast Water Discharged in 

U.S. Waters: A Proposed Rule by the Transportation Department and the Coast Guard. 67 FR 9632, 

March 4, 2002.

United States Coast Guard. 2004. Mandatory Ballast Water Management Program for U.S. Waters. U.S. 

Federal Register 69(144): 44952-44961 (July 28, 2004).
R-15

United States Coast Guard. 2008. Ballast Water Discharge Standard - Draft Programmatic 

Environmental Impact Statement. U.S. Coast Guard, Washington, DC, 218 pp.

United States Congress. 1990. Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990. 

U.S. Congress, Public Law 101-6461, enacted on November 29, 1990.

United States Congress. 1996. National Invasive Species Act of 1996. U.S. Congress, Public Law 104-

332, enacted on October 26, 1996.

United States Environmental Protection Agency (U.S. EPA). 1993. Methods for the Determination of 

Inorganic Substances in Environmental Samples. Report 600/R-93-100. Office of Research and 

Development, U.S. EPA, Washington, DC.

United States Environmental Protection Agency (U.S. EPA). 1997. Method 445.0: In vitro

Determination of Chlorophyll a and Pheophytina in Marine and Freshwater Algae by Fluorescence. 

U.S. EPA, Cincinnati, OH.

United States Environmental Protection Agency (U.S. EPA). 1999. Criteria for Evaluation of Proposed 

Protozoan Detection Methods. Report #EPA 815-K-99-02. Office of Research and Development, U.S. 

EPA, Cincinnati, OH. Available at: http://www.epa.gov/microbes/critprot.pdf.

United States Environmental Protection Agency (U.S. EPA). 2000. Deposition of Air Pollutants to the 

Great Waters. Third Report to Congress. U.S. EPA, Washington, DC.

United States Environmental Protection Agency (U.S. EPA). 2001. Aquatic Nuisance Species In Ballast 

Water Discharges: Issues and Options. Draft Report for Public Comment – September 10, 2001. Office 

of Water, Office of Wetlands, Oceans and Watersheds, and Office of Wastewater Management, U.S. 

EPA, Washington, D.C.

United States Environmental Protection Agency (U.S. EPA). 2002a. Methods for Measuring the Acute 

Toxicity of Effluents to Freshwater and Marine Organisms, 5th Edition. Report # EPA 821-R-02-012. 

Office of Water, U.S. EPA, Washington, DC.

United States Environmental Protection Agency (U.S. EPA). 2002b. Short-Term Methods for Estimating 

the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms, 4th Edition. Report # 

EPA 821-R-02-013. Office of Water, U.S. EPA, Washington, DC.

United States Environmental Protection Agency (U.S. EPA). 2002c. Short-Term Methods for 

Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms, 

3rd edition. Report # EPA 821-R-02-014. Office of Water, U.S. EPA, Washington, DC.

United States Environmental Protection Agency (U.S. EPA). 2003. Ambient Water Quality Criteria for 

Dissolved Oxygen, Water Clarity and Chlorophyllafor the Chesapeake Bay and Its Tidal Tributaries. 

Report EPA 903-R-03-002. Office of Water, U.S. EPA, Washington, DC.

United States Environmental Protection Agency (U.S. EPA). 2010 (July). Environmental Technology 

Verification Program (ETV) Draft Generic Protocol for the Verification of Ballast Water Treatment 

Technologies, Version 5.1.U.S. EPA ETV in cooperation with the U.S. Coast Guard Environmental 
R-16

Standards Division (CG-5224) and the U.S. Naval Research Laboratory. National Sanitation Foundation 

International, Ann Arbor, MI, 62 pp.+ appendices.

Unnevehr, L. J. and H.H. Jensen. 1996. HACCP as a Regulatory Innovation to Improve Food Safety in 

the Meat Industry. American Journal of Agricultural Economics 78(3):764-769.

Vaquer-Sunyer, R. and C.M. Duarte. 2008. Thresholds of hypoxia for marine biodiversity. Proceedings 

of the National Academy of Sciences of the United States of America 105:15452–15457.

Veldhuis, M.J.W., G.W. Kraaij, and K.R. Timmermans. 2001. Cell death in phytoplankton: correlation 

between changes in membrane permeability, photosynthetic activity, pigmentation and growth. 

European Journal of Phycology 36:1-13.

Vézie, C., J. Rapala, J. Vaitomaa, J. Seitsonen, and K. Sivonen. 2007. Effect of nitrogen and phosphorus 

on growth of toxic and nontoxic Microcystis strains and on intracellular microcystin concentrations. 

Microbial Ecology 43:443-454.

Victoria Environmental and Natural Resources Committee (ENRC). 1997.Report on Ballast Water and 

Hull Fouling in Victoria. Parliament of Victoria, ENRC, Victorian Government Printer, Melbourne, 

Australia.

Vollenweider, R.A. (ed.). 1974. A Manual on Methods for Measuring Primary Production in Aquatic 

Environments, 2nd edition. International Biological Program Handbook No. 12, Blackwell Scientific, 

Oxford, U.K.

Wang, X.C., F.G. Qiu and P.K. Jin. 2006. Safety of treated water for re-use purposes—comparison of 

filtration and disinfection processes. Water Science & Technology 53(9):213-220.

Wetzel, R.G. 2001. Limnology, 3rd edition. Academic Press, New York, NY.

Wetzel, R.G. and G.E. Likens. 2000. Limnological Analyses, 3rd edition. Springer-Verlag, New York, 

NY.

Williams, S.C., Y. Hong, D.C.A. Danavall, M.H. Howard-Jones, D. Gibson, M.E. Frischer and P.G. 

Verity. 1998. Distinguishing between living and nonliving bacteria: Evaluation of the vital stain 

propidium iodide and its combined use with molecular probes in aquatic samples. Journal of 

Microbiological Methods 32:225-236.

World Health Organization (WHO). 2008. Guidelines for Drinking-water Quality. Third Edition. 

Incorporating the First and Second Addenda. Volume 1: Recommendations. World Health Organization, 

Geneva.
A-1

APPENDIX A: DOCUMENTS ON BALLAST WATER TECHNOLOGIES PROVIDED TO THE PANEL 

This Appendix lists the documents available to the Panel for its assessment of ballast water technologies. These documents are 

available in the EPA Docket: Science Advisory Board Review of the Availability and Efficacy of Ballast Water Treatment Technology for 

EPA’s Office of Water and the United States Coast Guard (at www.regulations.gov under docket number EPA-HQ-OW-2010-0582). Shaded 

rows indicate those documents that the Panel used as reliable sources of credible data for their assessment. 

Table A-1. Documents Available to the Panel for its Assessment of Ballast Water Technologies

System Document Title Date

Group 1: Third-Party Reviews

General Ballast Water Treatment Technology: Current Status 2/1/2010

General

2009 Assessment of the Efficacy, Availability and Environmental Impacts of 

Ballast Water Treatment Systems for Use in California Waters 1/1/2009

General

October 2010 Update: Ballast Water Treatment Technologies for Use in 

California Waters 10/15/2009

General

Density Matters: Review of Approaches to Setting Organism-Based Ballast 

Water Discharge Standards 7/2/2005

General

International Convention for the Control and Management of Ships’ Ballast 

Water and Sediments, 2004 - List of ballast water management systems that 

make use of Active Substances which received Basic and Final Approvals 9/24/2009

General Ballast Water Treatment Advisory 6/8/2010

Group 2: Direct Data Reports and Supporting Information

Ecochlor® Ballast Water Treatment System

STEP 2006 Application Form - Section 4.0: Proof of Ballast Water Treatment 

Performance 6/28/2005

Ecochlor® Ballast Water Treatment System

Final Environmental Assessment Review of the Application by Atlantic 

Container Lines for Acceptance of the Vessel M/V Atlantic Compass and the 

EcochlorTM Inc. Technology into the USCG Shipboard Technology Evaluation 

(STEP) Program 8/1/2008

Ecochlor® Ballast Water Treatment System 

(Filtration+chlorine dioxide)

Final report of the land-based testing of the Ecochlor®-system, for Type 

Approval according to regulation-D2 and the relevant IMO guideline (April –

July 2008) 2/1/2009
A-2

System Document Title Date

Electro-Clean Ballast Water Management 

System

Development of technologies on test facility and procedures for the land-based 

test as a type approval test at ballast water treatment system 6/30/2005

Electro-CleenTM System

Information on the Type Approval Certificate of the Electro-CleenTM System 

(ECS) 2/20/2009

GloEn-PatrolTM Ballast Water Management 

System Type Approval Certificate of Ballast Water Management System 12/4/2009

Greenship's Ballast Water Management System Landbased Test Report - Test Cycle Summary 6/29/2005

Hyde GUARDIAN Ballast Water Treatment 

System

Environmental Acceptability Evaluation of the Hyde GUARDIAN Ballast Water 

Treatment System as Part of the Type Approval Process 4/20/2009

Hyde GUARDIAN Ballast Water Treatment 

System (Filtration+UV)

Final report of the land-based testing of the Hyde-GuardianTM -System, for Type 

Approval according to the Regulation D-2 and the relevant IMO Guideline 

(April - July 2008) 1/1/2009

Hyde GUARDIAN Ballast Water Treatment 

System Type Approval Certificate of Ballast Management System 4/29/2009

Hyde GUARDIAN Ballast Water Treatment 

System (Filtration+UV)

Shipboard Trials of Hyde "Guardian" System in Caribbean Sea and Western 

Pacific Ocean, April 5th - October 7th, 2008 4/1/2009

Hyde GUARDIAN Ballast Water Treatment 

System Type Approval of the Hyde GUARDIANTM Ballast Water Management System 5/7/2009

MSI (Filtration+UV)

MERC Land-Based Evaluations of the Maritime Solutions, Inc. Ballast Water 

Treatment System 11/1/2009

MH Systems (Deoxygenation)

Ballast water treatment by De-oxygenation with elevated CO2 for a shipboard 

installation 7/23/2003

NEI Venturi Oxygen Stripping (VOS)

Short-term Toxicity Testing of a De-oxygenation Ballast Water Treatment to 

Receiving Water Organisms. Final Report. 8/29/2008

NEI Venturi Oxygen Stripping (VOS)

Short-term Chronic Toxicity Testing of a De-oxygenation Ballast Water 

Treatment to Receiving Water Organisms. Final Report. 3/27/2009

NEI Venturi Oxygen Stripping (VOS) STEP 2006 Application Form. 3/1/2006

NEI Venturi Oxygen Stripping (VOS)

Type Approval Certificate of Ballast Water Management System; Ballast Water 

Management System Type Approval Compliance Certificate

7/6/2009; 

7/8/2007; 

1/19/2010
A-3

System Document Title Date

NEI Venturi Oxygen Stripping (VOS) 

(deoxygenation & decavitation)

Application for Type Approval Certification: NEI Treatment Systems' Venturi 

Oxygen Stripping Ballast Water Management System. 3/1/2007

NEI Venturi Oxygen Stripping (VOS) 

(deoxygenation & decavitation)

Evaluations of a Ballast Water Treatment to Stop Invasive Species and Tank 

Corrosion. 6/27/2005

OceanSaver® Ballast Water Management 

System Det Norske Veritas Type Approval Certificate 4/8/2009

OceanSaver® Ballast Water Management 

System Type Approval Certificate of the OceanSaver ® BWMS 4/17/2009

OceanSaver® Ballast Water Management 

System

Information on the Type Approval Certificate of the OceanSaver® Ballast Water 

Management System 5/6/2009

OptiMarin Ballast System Det Norske Veritas Type Approval Certificate 11/12/2009

Optimarin (Filtration+UV)

Land based testing of the OptiMarin ballast water management system of 

OptiMarin AS - Treatment Effect Studies 8/1/2008

Peraclean Toxic Shock as New Ballast Water Treatment Fails Test 2/9/2010

PureBallast 250-2500 Det Norske Veritas Type Approval Certificate 6/27/2008

PureBallast (Filtration+UV+TiO2) Land-based testing of the PureBallast Treatment System of AlfaWall AB 9/1/2008

PureBallast (Filtration+UV+TiO2) Shipboard testing of the PureBallast Treatment System of AlfaWall AB 5/1/2008

SEDNA ® 250 Type Approval Certificate of Ballast Water Management System 8/16/2008

SEDNA® ballast water treatment system using 

PERACLEAN® Ocean

Effective Protection Against “Stowaways”: Ballast Water Management System 

of Hamann and Evonik Receives Final Approval 6/11/2008

SEDNA®-System Final report of the land-based and shipboard testing of the SEDNA®-system 3/1/2008

SEDNA®-System

Summary of Additional Provisions of the Type Approval Certificate of Ballast 

Water Management System SEDNA 250 of Hamann AG 8/1/2008

Severn Trent De Nora (BalPure)

Washington State Dept. of Fish and Wildlife Application Package Ballast Water 

Treatment System 8/8/2005

Severn Trent De Nora (BalPure) Marrowstone Sodium Hypochlorite Mesocosm September 2004 9/1/2004

Severn Trent De Nora (BalPure)

Environmental Assessment Review of the Application for Acceptance of the 

SeaRiver Maritime Inc. S/R American Progress and Severn Trent de Nora 

BalPureTM System into the Shipboard Technology Evaluation Program (STEP) 2/1/2009
A-4

System Document Title Date

Severn Trent (Filtration+electrochlorination) Final report of the land-based testing of the BalPure®-BWT-System 1/1/2010

Severn Trent (Filtration+electrochlorination)

MERC Land-Based Evaluations of the Severn Trent De Nora BalPureTM BP1000 Ballast Water Management System 7/1/2009

Siemens SICURE Ballast Water Management 

System

A Great Lake Relevancy Preamble to the GSI Report on Land-Based Testing 

Outcomes for the Siemens SICURE Ballast Water Management System 4/28/2010

Siemens (Filtration+electrochlorination

MERC Land-Based Evaluations of the Siemens Water Technologies SiCURE 

Ballast Water Management System 11/1/2009

Siemens SICURE Ballast Water Management 

System (Filtration+electrochlorination)

Report of the Land-Based Freshwater Testing of the Siemens SiCURE Ballast 

Water Management System 5/15/2010

Group 3: G9 Files

"ARA Ballast" Ballast Water Management 

System (formerly Blue Ocean Guardian 

BWMS)

Application for Final Approval of "ARA Ballast" Ballast Water Management 

System 3/23/2010

Alfa Laval Ballast Water Management System 

(PureBallast) Basic Approval of Active Substances used by PureBallast management system 4/21/2006

Alfa Laval Ballast Water Management System 

(PureBallast)

Application for Final Approval of a ballast water management

system using Active Substances 12/15/2006

AquaStar Ballast Water Management System Application for Basic Approval of AquaStar Ballast Water Management System 3/18/2010

AquaTriComb BallastTM Water Treatment 

System

Application for Basic Approval of the AquaTriComb Ballast Water Treatment 

System 12/16/2008

AquaTriComb BallastTM Water Treatment 

System

Application for Basic Approval of the AquaTriCombTM Ballast Water Treatment 

System Corrigendum 6/29/2009

ATLAS-DANMARK, TG Ballastcleaner and 

TG Environmentalguard, 

Sunrui Ballast Water Management System, 

DESMI Ocean Guard, 

Blue Ocean Guard (BOG)

Report of the eleventh meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 12/1/2009

BalClor TM ballast water management system 

(formerly Sunrui BWMS) Application for Final Approval of BalClor TM ballast water management system 3/22/2010
A-5

System Document Title Date

BalPure®

Application for Basic Approval of the Severn Trent DeNora BalPure® Ballast 

Water Management System 8/28/2009

BalPure®

Application for Final Approval of the Severn Trent DeNora BalPure® Ballast 

Water Management System 3/28/2010

Blue Ocean Guardian (BOG) Ballast Water 

Management System

Application for Basic Approval of Blue Ocean Guardian (BOG) Ballast Water 

Management System 8/24/2009

Blue Ocean Shield Ballast Water Management 

System

Application for Basic Approval of the Blue Ocean Shield Ballast Water 

Management System 12/5/2008

BlueSeas Ballast Water Management System

Application for Basic Approval of the BlueSeas Ballast Water Management 

System 3/31/2010

CleanBallast! Comments on the report of the fourth meeting of the GESAMP-BWWG 2/4/2008

CleanBallast!

Application for Final Approval of a ballast water management system using 

Active Substances 9/7/2007

CleanBallast!

Application for Final Approval of the RWO Ballast Water Management System 

(CleanBallast) 11/28/2008

ClearBallast, 

Greenship Sedinox, 

AquaTriComb

Report of the ninth meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 5/5/2009

DESMI Ocean Guard Ballast Water 

Management System

Application for Basic Approval of the DESMI Ocean Guard Ballast Water 

Management System 8/19/2009

EcoBallast

Application for Basic Approval of the HHI Ballast Water Management System 

(EcoBallast) 12/9/2008

EcoBallast

Application for Final Approval of HHI Ballast Water Management System 

"EcoBallast" 8/20/2009

Ecochlor® Ballast Water Treatment System

Application for Basic Approval of the Ecochlor® Ballast Water Treatment 

System 3/20/2008

Ecochlor® Ballast Water Treatment System

Application for Final Approval of the Ecochlor® Ballast Water Management 

System 12/16/2008

Ecochlor® Ballast Water Treatment System

Application for Final Approval of the Ecochlor® Ballast Water Management 

System 3/28/2010

EctoSysTM A Swedish Disinfection System 1/13/2006
A-6

System Document Title Date

EctoSysTM Basic Approval of Active Substances used by EctoSysTM electrochemical system 4/21/2006

Electo Clean System, Clear ballast System, 

CleanBallast! System

Report of the fourth meeting of the GESAMP-Ballast Water Working Group 

(GESAMP-BWWG) 12/19/2007

Electro-Clean Ballast Water Management 

System

Application for Basic Approval of Active Substances used by Electro-Clean 

(Electrolytic Disinfection) Ballast Water Management System 12/16/2005

Electro-Clean Ballast Water Management 

System

Application for Final Approval of a ballast water management system using 

Active Substances (Electro-Clean Electrolytic Disinfection) 9/7/2007

Electro-Clean Ballast Water Management 

System

Application for Final Approval of a ballast water management system using 

Active Substances (Electro-Clean Electrolytic Disinfection). Corrigendum 3/12/2008

Electro-Clean Ballast Water Management 

System Application for Final Approval of the Electro-Clean System (ECS) 3/20/2008

En-Ballast

Application for Basic Approval of Kwang San Co., Ltd. (KS) Ballast Water 

Management System "En-Ballast" 8/25/2009

ERMA FIRST

Application for Basic Approval of the ERMA FIRST Ballast Water 

Management System 3/29/2010

General Guidelines on the Installation of Ballast Water Treatment Systems 3/1/2010

GloEn-Patrol, Ecochlor, 

SiCURE, Resource Ballast Technologies 

System

Report of the tenth meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 10/30/2009

GloEn-PatrolTM Ballast Water Management 

System Basic Approval of Active Substance used by GloEn-PatrolTM 9/7/2007

GloEn-PatrolTM Ballast Water Management 

System

Application for Final Approval of the GloEn-PatrolTM Ballast Water Treatment 

System 12/16/2008

Greenship Sedinox Ballast Water Management 

System

Application for Final Approval of the Greenship Sedinox Ballast Water 

Management System 12/12/2008

Greenship's Ballast Water Management System

Application for Basic Approval of a combined ballast water management system 

consisting of sediment removal and an electrolytic process using seawater to 

produce Active Substances (Greenship Ltd) 12/20/2007

HiBallast

Application for Basic Approval of Hyundai Heavy Industries Co., Ltd. (HHI) 

Ballast Water Management System (HiBallast) 8/24/2009
A-7

System Document Title Date

HiBallast, En-Ballast, 

OceanGuard, Severn Trent DeNora

Report of the twelfth meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 2/8/2010

Hitachi Ballast Water Purification System 

(ClearBallast)

Application for Basic Approval of Active Substances used by Hitachi Ballast 

Water Purification System (ClearBallast) 9/7/2007

Hitachi Ballast Water Purification System 

(ClearBallast)

Application for Final Approval of the Hitachi Ballast Water Purification System 

(ClearBallast) 12/11/2008

Hybrid Ballast Water Treatment System using 

Seawater Electrolytic Process

Basic Approval of Active Substances used by the Hybrid Ballast Water 

Treatment System using Seawater Electrolytic Process 12/14/2006

Hybrid Ballast Water Treatment System using 

Seawater Electrolytic Process, NKO3 BWTS, 

PureBallast, PureBallast

Report of the third meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 4/13/2007

Kuraray Ballast Water Management System Application for Basic Approval of Kuraray Ballast Water Management System 3/25/2010

MES Ballast Water Management System 

(FineBallast MF)

Application for Basic Approval of the MES Ballast Water Management System 

(FineBallast MF) 3/17/2010

NK Ballast Water Treatment System Request for re-evaluation of the proposal for the approval of Active Substances 8/18/2006

NK Ballast Water Treatment System

Basic Approval of Active Substances used by NK Ballast Water Treatment 

System 4/20/2006

NK-O3 BlueBallast System Application for Final Approval of the NK-O3 BlueBallast System (Ozone) 3/21/2008

NK-O3 BlueBallast System Application for Final Approval of the NK-O3 BlueBallast System (Ozone) 12/8/2008

OceanGuardTM Ballast Water Management 

System

Application for Basic Approval of the OceanGuardTM Ballast Water 

ManagementSystem 8/26/2009

OceanGuardTM Ballast Water Management 

System

Application for Final Approval of the OceanGuardTM Ballast Water 

ManagementSystem 3/25/2010

OceanSaver, Ecochlor,

NK-O3 BlueBallast System Report of the seventh meeting of the GESAMP-Ballast Water Working Group 7/28/2008

OceanSaver® Ballast Water Management 

System

Application for Basic Approval of a ballast water management system using 

Active Substances 9/7/2007

OceanSaver® Ballast Water Management 

System

Application for Final Approval of the OceanSaver® Ballast Water Management 

System (OS BWMS) 3/19/2008
A-8

System Document Title Date

Peraclean Ocean, ElectroClean

Report of the first meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 2/28/2006

Peraclean® Ocean Application for approval of an Active Substance for Ballast Water Management 4/15/2005

Peraclean® Ocean

Application for approval of an Active Substance for Ballast Water Management. 

Corrigendum 5/27/2005

Peraclean® Ocean & Sedna system

Application for Final Approval of a ballast water management system using 

Active Substances 9/7/2007

PurimarTM Ballast Water Management System

Application for Basic Approval of Techwin Eco Co., Ltd. (TWECO) Ballast 

Water Management System (PurimarTM) 3/9/2010

Resource Ballast Technologies System 

(cavitation combined with Ozone and Sodium 

Hypochlorite treatment)

Basic Approval of Active Substances used by Resource Ballast Technologies 

System (Cavitation combined with Ozone and Sodium Hypochlorite treatment) 4/6/2007

Resource Ballast Technologies System 

(cavitation combined with Ozone and Sodium 

Hypochlorite treatment)

Application for Final Approval of the Resource Ballast Technologies System 

(Cavitation combined with Ozone and Sodium Hypochlorite treatment) 12/19/2008

Resource Ballast Technologies System, GloEn 

Patrol, SEDNA using Percaclean Ocean, 

OceanSaver

Report of the fifth meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 1/25/2008

Siemens SiCURE

Application for Basic Approval of the Siemens SiCURE Ballast Water 

Management System 12/19/2008

Special Pipe Ballast Water Management 

System (combined with Ozone treatment), NK 

Ballast Water Treatment System, EctoSys

Report of the second meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 7/7/2006
A-9

System Document Title Date

Special Pipe Hybrid Ballast Water 

Management System (with Ozone), 

CleanBallast, 

NK-O3 BlueBallast System, Blue Ocean 

Shield, EcoBallast

Report of the eighth meeting of the GESAMP-Ballast Water Working Group 

(GESMP-BWWG) 4/8/2009

Special Pipe Hybrid Ballast Water 

Management System combined with Ozone 

treatment version

Basic Approval of Active Substances used by Special Pipe Ballast Water 

Management System (combined with Ozone treatment) 4/12/2006

Special Pipe Hybrid Ballast Water 

Management System combined with Ozone 

treatment version

Application for Final Approval of the Special Pipe Hybrid Ballast Water 

Management System (combined with Ozone treatment) 12/4/2008

Special Pipe Hybrid Ballast Water 

Management System combined with Ozone 

treatment version

Application for Final Approval of the Special Pipe Hybrid Ballast Water 

Management System combined with Ozone treatment version (SP-Hybrid 

BWMS Ozone version) 3/17/2010

Special Pipe Hybrid Ballast Water 

Management System combined with 

PERACLEAN ® Ocean (SPO-SYSTEM)

Application for Final Approval of the Special Pipe Hybrid Ballast Water 

Management System combined with PERACLEAN ® Ocean (SPO-SYSTEM) 3/29/2010

Sunrui ballast water management system Application for Basic Approval of Sunrui ballast water management system 8/24/2009

TG Ballastcleaner and TG Environmentalguard

Application for Basic Approval of the ballast water management system using 

“TG Ballastcleaner and TG Environmentalguard” as Active Substances 

(Toagosei Group) 12/26/2007

TG Ballastcleaner and TG Environmentalguard

Application for Final Approval of the JFE Ballast Water Management System 

(JFE-BWMS) that makes use of "TG Ballastcleaner® and TG 

Environmentalguard®" 8/20/2009

TG Ballastcleaner and TG 

Environmentalguard, Greenship's Ballast 

Water Management System, Electro-Clean 

System (ECS) Report of the sixth meeting of the GESAMP-Ballast Water Working Group 7/14/2008
B-1

APPENDIX B: LITERATURE REVIEW OF RECEPTION FACILITY STUDIES

The Panel identified and evaluated a number of studies in the published and gray literature that discuss 

reception facilities (RF) (Table B-1). 

Five studies have compared the effectiveness or costs of RF and shipboard treatment. In a study for the 

Canadian Coast Guard, Pollutech (1992) scored and ranked a variety of ballast water management 

approaches for vessels entering the Great Lakes, including ballast water exchange and several shipboard 

and land-based treatments, in terms of effectiveness, feasibility, maintenance and operations, 

environmental acceptability, cost, safety and monitoring. RF with discharge to a sanitary sewer (the only 

RF treatment scenario analyzed) ranked second out of 24 treatment and management approaches 

analyzed in the report.

In a second study for the Canadian Coast Guard, Aquatic Sciences (1996) considered RF alternatives 

(referred to as “pump off options”) for Great Lakes shipping and found them to be “technically feasible” 

and to “undoubtedly offer the best assurance of prevention of unwanted introductions.” The report 

further found that when installed onshore, “treatment options could have a more practical and 

enforceable application” than in shipboard installations, and concluded that “ship board treatment of 

ballast water appears to be logistically, economically, and particularly from the aspect of control, the 

least attractive method of ballast water treatment.” The report estimated that treatment ships could be 

provided at key ports throughout the Great Lakes to receive discharged ballast water and heat it to 

>65°C at an annualized cost of around $17 to $51 million, or alternatively a single treatment ship could 

operate at a site en route to the Great Lakes to treat all incoming ballast water at an annualized cost of

$2.7-2.8 million. Retrofitting costs to enable ships to discharge their ballast water to treatment ships 

were estimated at approximately $40,000 to over $200,000 per ship.

AQIS (1993a) developed designs and cost estimates to compare shipboard, land-based and treatment 

ship-based treatment at a port serving 140,000-ton bulk carriers. The shipboard design consisted of a 50-

μm strainer, with high-level ballast tank off-take pipes to reduce the discharge of ballast sediments and 

settled cysts or spore stages. The land-based designs included either 4,000 or 52,000 MT of storage, with 

coagulation, flocculation, granular filtration, UV disinfection, and thickening, dewatering and disposal 

of solids. The treatment ship design included 4,000 MT of storage, pressurized granular filters, UV, and 

solids management and disposal. Annualized costs were reported as $0.69/MT for shipboard treatment, 

$0.55/MT for treatment in a treatment ship, and $0.35-$0.62 for treatment in a land-based facility 

(depending on the type and size of storage used).

13

 13 Unless stated otherwise, the cost estimates cited in this appendix were converted from foreign currencies in the original 

publications into US dollars at the daily average interbank transfer rates reported at 

http://www.oanda.com/currency/historical-rates on the date of publication or presentation, or on the first day of the month 

where only the month of publication was given, and adjusted for inflation from the date of original publication to June 1, 

2010 using the calculator at http://inflationdata.com/inflation/Inflation_Calculators/InflationCalculator.asp, which is based on 

the U.S. Bureau of Labor Statistics' Consumer Price Index for all Urban Consumers (CPI-U).

Some costs (pipelines to transport ballast water from 

berths to treatment plants, and land costs) were not included in the RF alternatives, which reduced their 

estimated cost relative to the shipboard alternative. On the other hand, the Panel notes that the RF 

treatment analyzed here (granular filtration with coagulation and flocculation, followed by UV 

disinfection) would treat ballast water to a substantially higher standard than the shipboard alternative (a 

50 μm strainer with no disinfection); and that basing the analysis on large bulk carriers, which typically 

discharge the largest volumes of ballast water of the vessels using Australia’s ports (Table 4.1 in AQIS 

1993a), favored shipboard treatment.
B-2

Table B-1. Reports that discuss reception facilities (RFs) for onshore treatment of ballast water.

Report Discussion Conclusions

Pollutech 1992 Compares and ranks various shipboard and RF 

treatment approaches.

RF ranks 2nd out of 24 options.

AQIS 1993a Compares shipboard, land-based and treatment ship 

approaches in Australia.

Land-based and treatment ship are cheaper and more 

effective than shipboard.

AQIS 1993b Briefly discusses treatment ship and land-based

treatment in Australia.

RF is unlikely except in special circumstances.

Ogilvie 1995 Reviews possible treatment methods and estimates 

some costs for RFs.

Several methods show promise for RF.

Aquatic Sciences 1996 Compares shipboard, treatment ship, land-based and 

external source treatment.

RF is technically feasible and the most effective and 

cheapest approach.

NRC 1996 Briefly discusses advantages and disadvantages of RF. RF remains an option.

Gauthier & Steel 1996 Mentions shipboard, treatment ship and land-based

approaches.

RF is considered a poor option.

Victoria ENRC 1997 Briefly discusses RFs. RF is probably too costly at a large scale; may be 

viable at a smaller scale.

Greenman et al. 1997 Student report commissioned by the U.S. Coast Guard. RF is feasible at all sites considered.

Cohen 1998 Briefly discusses advantages and disadvantages of 

RFs.

Reeves 1998, 1999 Briefly discusses RFs. Lists RF as an alternative.

Oemke 1999 Briefly discusses advantages and disadvantages of RF. RF is feasible for some parts of the industry, such as 

VLCCs.

Dames & Moore 1998, 

1999

Briefly discusses RF. RF may be good option at oil export terminals with oil 

stripping plants.

Cohen & Foster 2000 Briefly discusses advantages and disadvantages of RF.

CAPA 2000 EPA-funded study estimates the cost of RF for 

California.

RF is technically feasible.

Rigby & Taylor 

2001a,b

Briefly discusses RF. Cost, availability, quality control may prevent RF 

development, but it might work for tankers that 

discharge oily ballast to RFs.

US EPA 2001 Briefly mentions RF.

California SWRCB 

2002

Briefly discusses RF. RF is an attractive option, at least for some parts of the 

industry.

Glosten 2002 Estimates upper-bound retrofit costs to discharge 

ballast to RFs.

NSF 2003 Mentions shipboard, RF and operational options for 

the longer term.

Shipboard seems the most challenging approach.

Hilliard 2006; Hilliard 

& Matheickal 2010

Compares and ranks various shipboard and RF 

treatment approaches for the Black Sea-Caspian Sea 

Waterway.

RF ranks 1st out of 16 options.

Brown & Caldwell

2007, 2008

Develops designs and estimates costs for RF at the 

Port of Milwaukee.

RF is feasible; treatment ship is cheaper than landbased.

California SLC 2009, 

2010

Briefly discusses advantages and disadvantages of RF. RF might be suitable for terminals with regular vessel 

calls such as cruise ships, or for the Port of Milwaukee.

Pereira et al. 2010 Uses simulation model to assess RF operation at a 

Brazilian port.

RF treatment would not affect port operations 

negatively.

Donner 2010a,b,c Compares RF and shipboard treatment. RF is more efficient, cheaper and safer.
B-3

AQIS (1993a) also developed a scenario for RF treatment of all the ballast water discharged in 

Australia, using both treatment ships and land-based treatment plants. Total capital costs for RF 

treatment were estimated at $330 million and annual operating costs at $6.7 million. The capital cost for 

outfitting one-year’s worth of visiting ships for shipboard treatment was estimated at $1 billion 

“ignoring the fit out of new ships in future years,” with estimated annual operating costs working out to 

$5.4 million. The study concluded that “land-based or port-based [=treatment ship] facilities are more 

economic and effective than numerous ship-board plants.” 

California’s State Water Resources Control Board (California SWRCB 2002) qualitatively evaluated

RFs and ten shipboard treatment alternatives for effectiveness, safety, and environmental acceptability. 

RF was the only approach rated acceptable in all three categories. There were reservations or unresolved 

questions about the effectiveness of all shipboard alternatives, about the safety of 80 percent of the 

shipboard alternatives, and about the environmental acceptability of 90 percent of the shipboard 

alternatives.

Hilliard (2006) (also reported in Hilliard and Matheickal 2010) compared an RF using conventional 

water treatment methods (such as granular filtration with disinfection) to 15 shipboard treatment 

approaches for vessels transiting the Black Sea-Caspian Sea Waterway. Based on scores for 13 technical

factors, RF treatment was ranked first. The study concluded that an RF, using standard water industry 

methods, would provide a cost effective solution if based at an appropriate port, but cautioned that this 

might be a less useful approach for some vessels. 

In each of these comparative studies, RF was judged to be as effective or more effective, and generally 

cheaper, than shipboard treatment. As noted, there are limitations to these studies and grounds for 

criticism; in particular, some were done over a decade ago and do not reflect current BWMS costs. 

However, these studies comprise the most detailed published comparisons of RF and shipboard 

treatment approaches available. In addition, the U.S. Coast Guard compiled a table of cost estimates 

from different studies (U.S. Coast Guard 2002). Figure B-1 shows all the estimates that were expressed 

as costs per metric ton or cubic meter of ballast water, and thus in a form that can be compared. In these 

estimates, RF treatment is generally more expensive than ballast water exchange and less expensive than 

shipboard treatment, though there is considerable overlap. These cost estimates also do not reflect 

current BWMS costs.
B-4

Figure B-1. Cost estimates listed in U.S. Coast Guard (2002). The Coast Guard converted Australian estimates to U.S. 

dollars at the Oct. 16, 2001 exchange rate, but did not adjust estimates for inflation. One m3 of ballast water is assumed to 

weigh 1 MT. Cost estimates (note log scale) for ballast water exchange are in blue, for RF treatment in green, and for 

shipboard treatment in red.

In three recent papers, Donner (2010a,b,c) argued that RF treatment is more efficient, less expensive, 

safer for the crew and the environment, and easier to monitor and verify than shipboard treatment, but 

that shipboard treatment has been pursued because it is “the solution of least resistance” politically. 

Other comparisons of RF and shipboard treatment in the literature consist of lists or brief discussions of 

their relative merits. These reports variously concluded that RF treatment is probably a superior or 

probably an inferior option compared to shipboard treatment, or that RF treatment is suitable for a 

particular part of the cargo fleet (Table B-1), but none provided analysis or data to support these 

conclusions. 

Two studies (in addition to AQIS (1993a) and Aquatic Sciences (1996), discussed above) provided

conceptual designs and cost estimates for RF treatment for specific regions. CAPA (2000), an EPAfunded study conducted for the California Association of Port Authorities, developed conceptual designs 

and cost estimates for constructing and operating ballast water treatment plants at cargo ports in 

California (Table B-2). These plans and estimates included pipelines from berths to plants; storage 

tanks; coagulation, flocculation, filtration and UV disinfection; thickening, dewatering and landfill 

disposal of residual solids; and discharge of effluent through an outfall pipeline. They did not estimate 

costs for land, permits, seismic evaluation, or retrofitting vessels to enable them to discharge ballast 

0.01

0.1

1

10

100

1000 $/MT
B-5

water to an RF. The study concluded that onshore treatment would be technically and operationally 

feasible, though there could be delays to vessels in some circumstances.

Table B-2. Cost estimates for onshore treatment in California (Source: CAPA 2000).

System Component Capital Costs Annual O&M 

Pipelines 146,950,000 –

Storage Tanks 76,235,000 –

Treatment Plants 22,510,000 2,018,000

Outfalls 1,380,000 –

Total 247,075,000 2,018,000

Brown & Caldwell (2007, 2008) developed designs and cost estimates for land-based and treatment ship 

approaches to treat ballast discharges from oceangoing ships arriving at the Port of Milwaukee. The first 

report assessed four land-based treatment systems: 

• 100-μm screening followed by UV treatment;

• Coarse screening followed by ozonation;

• 500-μm screening followed by membrane filtration to remove particles > 0.1 μm;

• 500-μm screening followed by hydrodynamic cavitation.

These were analyzed along with two systems for transferring and storing the discharged ballast water: 

discharge at berths into pipelines to land-based RF with storage tanks; and discharge to a barge that 

would store and carry the water to a land-based RF. Design criteria required a system capable of 

receiving ballast water at 680 MT/h, storage capacity of 1,900 MT, and treatment at 80 MT/h. The 

report concluded that all four treatment systems and both transport/storage systems are feasible, with 

UV treatment and hydrodynamic cavitation having the most promise for treating viruses (Brown & 

Caldwell 2007). The second report (Brown & Caldwell 2008) developed a design and cost estimate for 

retrofitting a barge to serve as a treatment ship, which would collect, store and treat ballast water. 

Treatment included a cloth media disk filter with a nominal pore size of 10 μm, and UV disinfection at 

an estimated minimum dose of 30 mJ/cm2

. The design criteria for this analysis included the capacity to 

receive ballast discharges at 2,300 MT/h, storage of 10,000 MT, and treatment at 230 MT/h, which is

around three times the flow rates and five times the storage required in the first report. Estimated costs 

from both studies are shown in Table B-3.
B-6

Table B-3. Cost estimates for onshore treatment for oceangoing ships at the Port of Milwaukee 

(Source: Brown & Caldwell 2007, 2008).

Treatment [1] Transport

— — — Capital Costs — — — Annual 

Pipelines [4] Storage Treatment Total O&M

100-μm screening & UV [1] Pipelines 2,973,000 1,252,000 615,000 4,840,000 11,500

Ozone [1] Pipelines 2,973,000 1,252,000 835,000 5,060,000 9,800

0.1-μm membrane filter [1] Pipelines 2,973,000 1,252,000 1,096,000 5,321,000 15,600

Hydrodynamic cavitation [1] Pipelines 2,973,000 1,252,000 2,608,000 6,833,000 20,900

100-μm screening & UV [1,2] Barge 261,000 522,000 615,000 1,398,000 367,000

Ozone [1,2] Barge 261,000 522,000 835,000 1,617,000 365,000

0.1-μm membrane filter [1,2] Barge 261,000 522,000 1,096,000 1,879,000 371

,000

Hydrodynamic cavitation [1,2] Barge 261,000 522,000 2,608,000 3,390,000 376,000

10-μm filter & UV [3] Treatment ship 0 2,695,000 866,000 3,561,000 514,000

[1] Design criteria are maximum ballast discharge of 680 MT/h,1,900 MT storage, and treatment rate of 80 MT/h.

[2] "Storage" refers to barge purchase and modification to use for ballast water transfer and storage, exclusive of the 

treatment system.

[3] Design criteria are maximum ballast discharge of 2,300 MT/h, 10,000 MT storage, and treatment rate of 230 

MT/h.

[4] Includes collection pumps, pipelines, a lift station and coarse screening.

Besides the need for facilities to receive, store and treat ballast water from ships, ships must be modified 

so they can safely and rapidly discharge ballast water to RFs. This requires modification of a ship’s pipe 

system and possibly larger ballast pumps, to raise the water to deck level and/or to discharge it quickly 

enough. Cost estimates have ranged from around $15,000 to $540,000 for container ships (Pollutech 

1992; Glosten 2002), $15,000 to $500,000 for bulkers (Pollutech 1992; CAPA 2000), and less than 

$140,000 to around $2.3 million for tankers (Victoria ENRC 1997; Glosten 2002) (Table B-4). Most of 

these estimates explicitly included the replacement of existing pumps with more powerful pumps where 

needed (AQIS 1993a; Aquatic Sciences 1996; Dames & Moore 1998; CAPA 2000; Glosten 2002; 

Brown & Caldwell 200814). The cost to outfit a new ship was estimated to be less than the cost to

retrofit an existing ship (AQIS 1993b), perhaps by an order of magnitude (CAPA 2000). Some reports 

provided little or no explanation of their retrofit/modification estimates (Pollutech 1992; AQIS 1993a; 

Aquatic Sciences 1996; Dames & Moore 1998). Victoria ENRC (1997) provided a materials list for a 

bulk carrier, and noted that a tanker “with its ballast lines running on deck would have a considerable 

lower installation cost.” CAPA (2000) provided a cost breakdown for modifying a bulker, and stated

that modifying a tanker would generally cost more. 

 14 Glosten (2002) designed the pumps and pipes to be large enough to enable ships to deballast completely at berth during a 

typical cargo loading period. Brown & Caldwell (2008) found, based on dynamic head vs. flow curves, that Great Lakes 

bulkers would not need larger ballast pumps—that is, with their existing pumps the ships could fully deballast while at berth 

during the time it takes to load cargo.
B-7

Table B-4. Cost estimates for retrofitting ships to discharge ballast water to a treatment facility. Where the 

data are available, length is given in feet, size in deadweight tons (DWT), ballast water capacity in metric tons (MT), 

and maximum ballast discharge rate in metric tons per hour (MT/h), in parentheses following the ship type.

Ship Type Capital Cost Report

Great Lakes bulker, break-bulk or container $13,200–26,500 Pollutech 1992

Small container $20,400 AQIS 1993a

Large bulker (140,000 DWT; 45,000 MT; 4,000 MT/h) $204,000 AQIS 1993a

Great Lakes bulker $40,400–202,00 Aquatic Sciences 1996

Handysize bulker (520'; 22,000 DWT) $142,000 Victoria ENRC 1997

Container $53,200-173,000 Dames & Moore 1998 [1]

Container or bulker (1,000 MT/h) $502,000 CAPA 2000

Tanker (869'; 123,000 DWT; 75,850 MT; 6,400 MT/h) $2,3230,000 Glosten 2002

Bulker (735’; 67,550 DWT; 35,000 MT; 2,600 MT/h) $131,000 Glosten 2002

Break-bulk (644'; 40,300 DWT; 26,850 MT; 3,000 MT/h) $373,000 Glosten 2002

Container (906'; 65,480 DWT; 19,670 MT; 2,000 MT/h) $540,000 Glosten 2002

Car carrier (570'; 13,847 DWT; 6,600 MT; 550 MT/h) $198,000 Glosten 2002

Bulker (469’; 5,700 MT; 570 MT/h) $60,000 Brown & Caldwell 2008

Bulker (722’; 18,000 MT; 2,300 MT/h) $203,000 Brown & Caldwell 2008

[1] Estimate developed by the Pacific Merchant Shipping Association.

Glosten (2002) and Brown & Caldwell (2008) provided the most detailed estimates. Glosten (2002) 

estimated ship retrofit/modification costs for five ships representing common vessel types in Puget 

Sound (Table B-4). The modifications were designed to “allow ballast transfer with minimal disruption 

to current operations” including sizing them for deballasting completely at berth during the time needed 

to load cargo, eliminating any need to start deballasting before arriving at berth. For each vessel type, 

the authors selected ships that “had ballast systems with capacities on the upper end of vessels that call 

on Puget Sound to attempt to establish an upper-bound on retrofitting costs.” In selecting pipe sizes and 

other elements “every attempt was made to capture an upper bound on the modification costs associated 

with each vessel type surveyed,” including the installation of “a completely new piping system to 

provide the ability to fill and empty each ballast tank separately.” Notably, this new piping system was 

included in the tanker estimate even though it is not needed on crude oil tankers, the type of tanker 

analyzed, where “a simpler, lower-cost solution” exists. It was included because it could be needed on 

some other ships (i.e. product tankers) in the same general category, and this produced by far the highest 

cost estimate in the study.15 The modifications were also designed to allow ballast water transfer in 

either direction between a ship and a RF (either onto or off a ship),16 which in some cases may raise the 

cost over what is needed to only discharge ballast water to RFs.

Brown & Caldwell (2008) provided analyses, conceptual designs, drawings and cost estimates for 

modifying two sizes of ocean-going bulkers serving the Great Lakes, based on a smaller actual ship and 

a larger hypothetical ship (Table B-4). These designs were also sized to allow the ship to initiate and 

complete deballasting at berth during cargo loading.

 15 Consistent with the study’s aim of quantifying “the capital cost required to provide the maximum capability in a ballast 

transfer system, to represent a maximum capital investment” for each vessel category (Glosten 2002).

16 This ability was included to accommodate the possibility of loading “clean” ballast, an approach that is not considered to 

be onshore treatment in this report.
B-8

The potential for treating ballast discharges with RFs has also been recognized in laws, regulations, 

guidelines and treaty conventions. The U.S. Nonindigenous Aquatic Nuisance Prevention and Control 

Act (NANPCA) of 1990 and the National Invasive Species Act (NISA) of 1996 directed the U.S. Coast 

Guard to fund research on ballast water management, specifically noting that technologies in “landbased ballast water treatment facilities” could be included, and to investigate the feasibility of using or 

modifying onshore ballast water treatment facilities used by Alaskan oil tankers to reduce the 

introduction of exotic organisms (§§1101(k)(3), 1104(a)(1)(B), 1104(a)(2) and 1104(b)(3)(A)(ii) in U.S. 

Congress 1990, 1996). In the interim and final rules implementing NISA, the U.S. Coast Guard 

specifically included discharge to a RF as a means of meeting NISA’s ballast discharge requirements, 

and required ships to keep records of ballast water discharged to RFs (US Coast Guard 1999, 2001), 

although the Coast Guard eliminated these provisions when it concluded that it did not have the 

authority to regulate or approve RFs (US Coast Guard 2004). The U.N. International Maritime 

Organization’s 1991 Guidelines stated that “Where adequate shore reception facilities exist, discharge of 

ship’s ballast water in port into such facilities may provide an acceptable means of control” (IMO 1991 

and IMO 1993, §7.5 Shore Reception Facilities). The IMO’s 1997 Guidelines stated that “Discharge of 

ship's ballast water into port reception and/or treatment facilities may provide an acceptable means of 

control. Port State authorities wishing to utilize this strategy should ensure that the facilities are 

adequate...If reception facilities for ballast water and/or sediments are provided by a port State, they 

should, where appropriate, be utilized” (IMO 1997, §7.2.2, §9.2.3). The IMO’s 2004 Convention stated

that “The requirements of this regulation do not apply to ships that discharge ballast water to a reception 

facility designed taking into account the Guidelines developed by the Organization for such facilities” 

(IMO 2004, Regulation B-3.6). The IMO adopted specific guidelines for RFs (IMO 2006), and 

recognized RFs as an alternative in IMO 2005b (§1.2.3), as have Australia, New Zealand and Canada in 

their ballast water regulations (AQIS 1992; New Zealand 1998, 2005; Canada 2000, 2007).

Additional Literature Cited

Australian Quarantine and Inspection Service (AQIS). 1992. Controls on the Discharge of Ballast Water 

and Sediment from Ships Entering Australia from Overseas. AQIS Notice (Barrier Co-ordination) 92/2. 

AQIS, Canberra, Australia.

Canadian Marine Advisory Council (CMAC). 2000. Guidelines for the Control of Ballast Water 

Discharge from Ships in Waters under Canadian Jurisdiction. TP 13617, CMAC, Ottawa, Canada.

Canadian Marine Advisory Council (CMAC). 2007. A Guide to Canada’s Ballast Water Control and 

Management Regulations. TP 13617E, Transports Canada, Ottawa, Canada.

Donner, P. 2010a. Ballast Water Treatment Ashore Brings More Benefits. Pages 97-105 in: Emerging 

Ballast Water Management Systems. Proceedings of the IMO-WMU Research and Development Forum, 

26-29 January 2010, Malmö, Sweden. A GloBallast-Global Industry Alliance and World Maritime 

University Initiative. Bellefontaine, N., F. Haag, O. Lindén and J. Matheickal (eds.). WMU Publication, 

Malmö, Sweden.

Donner, P. 2010b. Ballast water treatment ashore—better for the environment and for seafarers. WMU 

Journal of Maritime Affairs 9(2): 191-199.
B-9

Donner, P. 2010c. Is there a case for shore-based ballast water treatment facilities? 5th International 

Conference on Ballast Water Management 2010. Singapore, Nov. 1-4, 2010. Session 1: Ballast Water 

Management Plans by Ports and Flag States.

Greenman, D., K. Mullen and S. Parmar. 1997. Ballast Water Treatment Systems: A Feasibility Study. 

Produced in cooperation with ENS Chris Freise, U.S. Coast Guard Office of Response. Commissioned 

by the U.S. Coast Guard and Worcester Polytechnic Institute. Submitted to Professor Matthew Ward, 

Project Center, Worcester Polytechnic Institute, Washington, DC, 59 pp.

Hilliard, R.W. 2006. Assessment of Shipping Traffic and Ballast Water Movements to and from Caspian 

Sea, and Preliminary Appraisal of Possible Ballast Water Management Options. Draft Report. Prepared 

for the International Maritime Organization. URS Corporation. Accessed at: 

http://www.caspianenvironment.org/Newsite/Activities-Ballast%20Waters.htm

Hilliard R.W. and J.T. Matheickal. 2010. Alternative Ballast Water Management Options for Caspian 

Region Shipping: Outcomes of a Recent CEP/IMO/UNOPS Project. Pages 119-138 in: Emerging 

Ballast Water Management Systems. Proceedings of the IMO-WMU Research and Development Forum, 

26-29 January 2010, Malmö, Sweden. A GloBallast-Global Industry Alliance and World Maritime 

University Initiative. Bellefontaine, N., F. Haag, O. Lindén and J. Matheickal (eds.). WMU Publication, 

Malmö, Sweden.

International Maritime Organization (IMO). 1991. International Guidelines for Preventing the 

Introduction of Unwanted Aquatic Organisms and Pathogens from Ships' Ballast Water and Sediment 

Discharges. IMO, Marine Environment Protection Committee, Resolution MEPC 50(31), adopted 4 July 

1991.

International Maritime Organization (IMO). 1993. Guidelines for Preventing the Introduction of 

Unwanted Aquatic Organisms and Pathogens from Ships' Ballast Water and Sediment Discharges. IMO, 

Resolution A.774(18), adopted 4 November 1993.

International Maritime Organization (IMO). 1997. Guidelines for the Control and Management of Ships' 

Ballast Water to Minimize the Transfer of Harmful Aquatic Organisms and Pathogens. IMO, 20th 

Assembly, Resolution A.868(20), adopted 27 November 1997.

International Maritime Organization (IMO). 2006. Guidelines for Ballast Water Reception Facilities 

(G5). IMO, Marine Environment Protection Committee, Marine Environment Protection Committee 

(MEPC), Resolution MEPC 153(55), adopted 13 October 2006.

National Science Foundation (NSF) (2003) Engineering Controls for Ballast Water Discharge: 

Developing Research Needs. Report of a workshop held on April 28-30, Seattle, WA. Bioengineering 

and Environmental Systems Division of the Engineering Directorate, NSF, Arlington, VA.

New Zealand Ministry of Agriculture and Forestry (NZMAF). 1998. Import Health Standard For Ships' 

Ballast Water From All Countries (Biosecurity Act 1993). NZ MAF, Wellington, New Zealand.

New Zealand Ministry of Agriculture and Forestry (NZMAF). 2005. Import Health Standard For Ships' 

Ballast Water From All Countries. Issued pursuant to Section 22 of the Biosecurity Act 1993. NZ MAF, 

Wellington, New Zealand.
B-10

Ogilvie, D.J. 1995. Land-based treatment options. Pages 113-123 in: Ballast Water. A Marine Cocktail 

on the Move. Proceedings of the National Symposium, 27-29 June 1995, Wellington, New Zealand. The 

Royal Society of New Zealand. Miscellaneous Series 30.

Pereira, N.N., R.C Botter, H.L. Brinati and E.F. Trevis. 2010. A Study of Ballast Water Treatment 

Applied on Iron Ore Ports in Brazil Using Discrete Simulation. Pages 77-91 in: Emerging Ballast Water 

Management Systems. Proceedings of the IMO-WMU Research and Development Forum, 26-29 

January 2010, Malmö, Sweden. A GloBallast-Global Industry Alliance and World Maritime University 

Initiative. Bellefontaine, N., F. Haag, O. Lindén and J. Matheickal (eds.). WMU Publication, Malmö, 

Sweden.
C-1

APPENDIX C: FURTHER INFORMATION ON STATISTICS AND 

INTERPRETATION 

A major challenge of sampling at low organism concentrations is that many samples will have zero live 

organisms because the few live organisms present are missed. Therefore to improve the probability of 

detecting them, large volumes must be sampled and excellent techniques must be used to enable 

detection (Figure C-1).

Consider the following examples from Lee et al. (2010): from the Poisson distribution, if 1 m3 of ballast 

water was sampled from a ballast water discharge that had a known average concentration of 10 

zooplankton-sized organisms m-3 over the entire ballast water volume, about 95 percent of the samples 

would contain 4-17 organisms m-3. As the concentration of organisms decreases, the frequency 

distribution becomes increasingly skewed, and there is a high probability of obtaining a sample with 

zero organisms. Thus, if the sample concentration is 1 organism m-3, the probability of a 1 m3 sample 

containing zero organisms is 36.8 percent. If the sample concentration is only 0.01 organism m-3, or 1 

organism in 100 cubic meters of ballast water, the probability of obtaining a sample with zero organisms 

is ~99 percent. Moreover, 

If a small volume is used to evaluate whether the discharge meets a standard, the sample 

may contain zero detectable organisms, but the true concentration of organisms may be 

quite high....For example, even with a relatively high concentration of 100 organisms m3

, only about 10% of 1-L samples will contain one or more organisms. Furthermore, even 

if zero organisms are detected in a 1-L sample, the upper possible concentration, based on 

a 95% confidence interval, is about 3,000 organisms m-3

....The general point is that more 

organisms may be released in ballast discharge using a stringent standard paired with a 

poor sampling protocol than a more lenient standard paired with a stringent sampling 

protocol. (Lee et al. 2010, p.72).

The available methodologies for testing compliance with the IMO standards for zooplankton-sized 

organisms are at or near the analytic detection limits. The following example from the ETV Protocol 

(U.S. EPA 2010) illustrates the problem: For the desired minimum precision in quantifying 

zooplankton-sized organisms, consider an example where the upper bound of the Chi-square statistic 

should not exceed twice the observed mean (corresponding to a coefficient of variation of 40 percent, 

which is relatively high). Then, if 6 or fewer live organisms are counted, the upper bound of the 95% CI 

for the volume sampled does not exceed the IMO/Phase-1 performance standard for zooplankton-sized 

organisms (< 10 viable individuals per m3

):

• Coefficient of variation (CV) = standard deviation (SD) divided by the mean (M).

• For the Poisson distribution, the variance (V) = SD2 = M.

• Substituting the critical value of the mean, 6: CV = 61/2/6 ≈ 40%.

The volume needed to find and quantify 6 live organisms per m3 depends on the whole-water 

sample volume, the concentration factor, and the number of subsamples examined. Very large 

sample volumes (tens of m3

) are required to quantify viable zooplankton-sized organisms 

(assuming 20 mL of the concentrated sample is analyzed), and each sample must be concentrated 

down to a manageable volume (concentrating 3 m3 to 1 L would yield a concentration factor of 

3,000). Based on the Poisson distribution for a 95% CI from the Chi-square distribution, 30 m3
C-2

(30,000 L) must be sampled in order to find and count < 10 organisms m-3 with the desired level 

of precision. The total sample volume can be reduced if the concentration factor is increased (and 

the same subsample volume analyzed), if the CI is also lowered (e.g., from 95% to 90%) or the 

subsample volume analyzed is increased (e.g., from 20 mL to 40 mL). Notably, as the 

concentration factor increases, the likelihood of losing organisms or inadvertently killing them in 

the sample processing steps increases, thus creating an artifact that overstates the effectiveness of 

the treatment (see Section 6.2.4 (A)).

The ETV Protocol provides examples of the sample size needed to provide the level of precision needed 

to achieve a 95% upper confidence limit that is no more than twice the observed mean and does not 

exceed the targeted concentration. If the volume of subsample that is analyzed is increased, then 

validation experiments should be conducted to ensure that counting accuracy is acceptably high. The 

problem is exacerbated for zooplankton-sized organisms because they are sparse compared to organisms 

in the next smaller class (here, referred to as “protist-sized” organisms, or organisms ≥10 μm and < 50 

μm in minimum dimension). The Poisson distribution assumption still applies to this smaller size class, 

and the ETV Protocol provides examples with a more stringent level of precision than is used for the 

larger size class (Table C-2; U.S. EPA 2010). At present, confirmation of the Phase 1 standard (< 10 

protist-sized organisms mL-1

) represents the practical limit that can currently be achieved by testing 

facilities in the U.S. (e.g., MERC 2009, 2010a, 2010b; Great Ships Initiative 2010).

Table C-1. Sample volume of treated ballast water required relative to performance standards for 

organisms ≥10 μm and <50 μm (nominally protists), assuming that the desired level of precision is set at a 

CV of < 10%. These are the required whole-water sample volumes that must be concentrated to 1 L as a 

function of N, the number of 1-mL subsamples analyzed. (Source: U.S. EPA 2010).

N= 2 3 4

Concentration (i.e. performance 

standard) (individuals mL-1)

Sample Volume Required (L)

0.01 6,000 4,000 3,000

0.1 600 400 300

1 60 40 30

10 6 4 3

Laboratory experiments with protist cultures support use of the Poisson distribution

A workshop was held to evaluate four methods for enumerating living protists in treated ballast water 

(Nelson et al. 2009, Steinberg et al., accepted with revisions). Live and dead cells were counted using 

flow cytometry, an enhanced flow-through system with imaging capacity (FlowCAM®, Fluid Imaging 

Technologies, Yarmouth, ME), direct counts of samples collected on membrane filters, and direct counts 

using a Sedgewick Rafter counting chamber. All techniques used fluorescent stains to differentiate 

between live and dead cells. Counting methods were tested with several ratios and densities of live and 

dead Tetraselmis sp., a small phytoflagellate. In these trials, comparisons were conducted under ideal 

conditions with no debris (except for one sample) or particulate matter and with a single target species. 

Data were evaluated to determine whether they conformed to a Poisson distribution by determining if 

the variance was equal to the mean. At low concentrations of living cells (approximately 10 mL-1 to 100 

mL-1), there was no evidence to reject the Poisson hypothesis (Nelson et al. 2009).
C-3

Accuracy and precision in sparse samples following a Poisson distribution

A series of laboratory experiments was conducted to assess the accuracy and precision of enumerating 

zooplankton- and protist-sized organisms at a variety of densities (Lemieux et al. 2008). Inert 10-μm 

standardized microbeads at densities of 1, 5, 10, 50, 100, 500, and 1,000 microbeads per mL of artificial 

seawater represented protist-sized organisms, and 150-μm microbeads at 10, 30, and 60 microbeads per 

500 mL represented zooplankton-sized organisms. Such inert, standardized polymer microbeads were 

used rather than organisms to eliminate any potential bias, and artificial (rather than natural) seawater 

was used to avoid inclusion of various organic particles (e.g., detritus) that could interact with the 

microbeads and confound interpretations. Here, microbeads served as proxies, and it is acknowledged 

they are an imperfect representation of living organisms (e.g., microbeads do not exhibit the swimming 

behavior of many planktonic organisms; living organisms can cling to nets or filters and can also be 

squeezed through a net more readily than microbeads). Nonetheless, if the items of interest in a sparse 

concentration – be they microbeads or living organisms in treated ballast water – are well mixed, the 

Poisson distribution should be applicable. In addition, as stated previously, a continuously isokinetically 

taken sample whose contents are completely counted avoids problems associated with the spatial 

distribution of the organisms. 

At each microbead density, the percent difference of the observed mean from the expected mean 

indicated counting accuracy, and the CV indicated the level of precision. In this study, benchmarks for 

acceptable accuracy and precision were established at a percent difference of 10 percent and a CV of 0.2 

(20 percent), respectively. For the “protist” microbeads, the 50 - 1,000 mL-1 concentrations were not 

significantly different, with acceptable accuracy and precision below the 10 percent and 20 percent

benchmarks, respectively. Unfortunately, however, analysis of the “zooplankton” microbead populations 

at all densities showed poor precision, with CVs well above 20 percent, and only counts at the highest 

density showed a CV < 100 percent. All densities of “zooplankton” microbeads showed acceptable 

accuracy (i.e., a percent difference < 10%) after sufficient aliquots were examined to result in a stable 

mean. 

From this work, Lemieux et al. (2008) recommended that samples for analysis of protist-sized organisms 

should be concentrated by at least a factor of five, and that at least four replicate counting chambers 

(e.g., four Sedgewick Rafter slides) should be analyzed for acceptable accuracy and precision, including

evaluation of at least 10 random rows (from a total of 20) of each counting chamber. Importantly, for 

zooplankton-sized organisms, Lemieux et al. (2008) determined the earlier (draft) ETV protocol 

recommendations for sample sizes as inadequate to achieve acceptable precision. The data from these 

microbead experiments indicated, instead, that this size class requires a sample size of greater than 6 m3

, 

concentrated to 0.5 L (i.e., concentrated by a factor of 12,000), and analysis of at least 450 1-mL 

aliquots, considering that CVs at the highest volumes were > 20%. As higher concentration factors were 

likely unrealistic, it was suggested that larger sample sizes and improved analytical methods should be 

used. Lemieux et al. (2008) also noted that these laboratory trials represented a “best case” situation 

because the study was conducted under simplified, “ideal” conditions rather than with natural organism 

assemblages in natural seawater.

When concentrations are close to the performance standard, a single sample may require too large a 

volume of water to be logistically feasible. In that case, complete, continuous time-integrated sampling 

(with the entire volume analyzed) and combining samples across multiple trials can improve resolution 

while maintaining statistical validity. To that end, Miller et al. (2011) applied statistical modeling (based 

on the Poisson distribution) to a range of sample volumes and plankton concentrations. They calculated 

the statistical power of various sample volume and zooplankton concentration combinations to 
C-4

differentiate various zooplankton concentrations from the proposed standard of < 10 m-3. Their study 

involved a two-stage sampling approach. Stage 1 checked compliance based on a single sample, which 

was expected to be effective when the degree of noncompliance was large. Stage 2 combined several 

samples to improve discrimination (1) when concentrations are close to the performance standard, or (2) 

when a large-volume, single-trial sample would be logistically problematic, or both. The Stage 2 

approach took advantage of the fact that the sum of several Poisson random variables is still a Poisson 

distribution, and is called the “summed Poisson method.” Stage 2 also compared the summed Poisson 

approach to power calculations using standard t-tests, the nonparametric Wilcoxon Signed Rank test 

(WSRT), and a binomial test, all well-known statistical techniques. The summed Poisson approach had 

more statistical power relative to the other three statistical methods. Not surprisingly, as noncompliant 

concentrations approached the performance standard, the sampling effort required to detect differences 

in concentration increased. The major conclusions from this study are presented in Section 3.2.1.

The major finding from Miller et al. (2011) is that three trials of time-integrated sampling of 7 m3 (and 

analyzing the entire concentrated sample from the 21 m3) from a ship’s BW discharge can theoretically 

result in 80% or higher probability of detecting noncompliant discharge concentrations of 12 vs. 10 live 

organisms m-3. Thus, pooling volumes from separate trials will allow lower concentrations to be 

differentiated from the performance standard, although the practicability and economic costs of doing so 

have not been evaluated. Moreover, the practical limits of increased statistical sample sizes may already 

tax the capabilities of well-engineered land-based ballast water test facilities used in verification testing.

Shipboard testing in the U.S. has been done on a pilot scale to date (i.e., the USCG Shipboard Testing 

Evaluation Program, STEP), but we imagine that pooling volumes from multiple trials might also be 

problematic on vessels used for shipboard verification testing and compliance testing. According to 

Table C-1, to meet a standard ten-fold more stringent than the IMO D-2/ Phase 1 standard would require 

anywhere from 120-600 m3 of whole-water sample volumes, which is impracticable at this point – test 

facilities in the U.S. typically analyze ~5 m3 of water per test (e.g., MERC 2009a, 2010a, 2010b; Great 

Ships Initiative 2010).

Additional challenges of sampling large volumes 

Lee et al. (2010) calculated the probability of finding one or more organisms in a sample as 1-e

c*v (1 

minus the probability of finding no organisms) for a series of organism concentrations and sample 

volumes, where e is the natural log, c is the true concentration of organisms, and v is the sample volume 

(Table C-3). The authors used the following assumptions: 

• Performance standards are for the concentration of organisms in the ballast discharge (rather 

than the maximum number of organisms), so that the purpose of sampling is to estimate the 

“true” concentration of organisms in the discharge, referred to as average-based sampling; 

• The organisms are randomly distributed and therefore amenable to modeling with the 

Poisson distribution, as above; 

• All organisms are counted, with no human or instrumentation errors, so that any variation 

among samples for a given population (species) is from the natural stochasticity of sampling; 

• The sample volume is calculated from the total volume of ballast water filtered 

(concentrated) and the filtrate volume that is subsampled. For example, following Lemieux et 

al. (2008): 100 m3 of ballast water is filtered through a net to retain the zooplankton-sized 

organisms; the organisms are rinsed from the net, collected, and diluted to 1 L of water to 

give a concentration factor of 100,000:1. The organisms from 20 1-mL subsamples are 
C-5

counted: Total sample volume = 20 mL subsamples/1000 mL concentrated sample x 100 m3

ballast water filtered = 2 m3.

As Table C-2 illustrates, 100 L of ballast must be sampled to have a > 99% probability of detecting at 

least 1 zooplankton-sized organism when the true concentration is 100 organisms per m3

. When small 

sample volumes are collected, the probability of detecting an organism is low even at relatively high 

organism concentrations; for example, organisms will be detected in fewer than 10% of subsamples if a 

1-L sample is taken and the “true” concentration is 100 organisms m-3. This analysis also illustrates that 

when no organisms are detected from a relatively small sample, the true concentration in the ballast tank 

may still actually be large – it depends on the sample volume collected.

Lee et al. (2010) then estimated the upper possible concentration (UPC, upper 95% CI) of organisms 

actually present in ballast water from the number of zooplankton-sized organisms in a sample volume 

(ranging from 100 mL to 100 m3

) based on the Poisson distribution. As Table C-3 shows, 0 organisms 

detected in 1 m3 of sample could correspond to a true concentration of organisms in the ballast tank of 

up to ~3.7 organisms m-3. The error is much larger for a small sample volume of 1 L; 0 organisms 

detected could correspond to a true concentration of ~3,700 organisms m-3.

Table C-2. Probability of detecting ≥ 1 zooplankton-sized organism for sample volumes (100 mL to 

300 m3) and ballast water concentrations (0 to 100 organisms m-3). Gray boxes indicate probabilities 

of detection ≥ 0.95. (Source: Lee et al. 2010).
C-6

Third, in the above analyses, the true concentrations of zooplankton-sized organisms are known. 

The goal in sampling unknown concentrations of organisms in ballast water is to accurately 

assess whether a given BWMS treats water with true organism concentrations that meet a given 

performance standard. Inherent stochasticity of sampling may result in an indeterminate 

category, as well, and the probability of obtaining an indeterminate evaluation increases with 

decreasing sample volume and increasing stringency of the ballast water standard (Figure C-1). 

Based on this analysis, it would be necessary to sample ~0.4 m3 of ballast water to determine 

whether the IMO standard of < 10 zooplankton-sized organisms m-3 was met if fewer than 

approximately 10 organisms were observed in the sample (Figure C-1B).

Table C-3. Upper possible concentration (UPC) of zooplanktonsized organisms based on one and two tailed 95% exact confidence 

intervals when zero organisms are detected in a range of sample 

volumes. (Source: Lee et al. 2010). 
C-7

Spatially Aggregated Populations – Negative Binomial Distributions

This section illustrates how difficult statistical analyses can become when working with spatially 

aggregated populations. It further emphasizes the gains made from doing a complete count of a 

representative sample that has been continuously and isokinetically taken. 

If organisms are aggregated (i.e., in clumped or contagious populations) rather than randomly distributed 

in a ballast tank, a different statistical approach is required. For aggregated populations, the variance 

exceeds the mean (negative binomial distribution, σ2 > μ); thus, as the variance increases, the number of 

organisms in a random sample is increasingly unpredictable. Because it is more difficult to accurately 

estimate the true concentration, more intensive sampling is required. Lee et al. (2010) recommend use of 

the negative binomial distribution to model aggregated populations. This distribution can be used to 

predict the probability of finding a certain number of organisms in a sample. It is defined by the mean 

(μ) and the dispersion or size parameter (θ = μ2

/(σ2 - μ), where σ

2 = the variance; the smaller the 

dispersion parameter, the more aggregated the population.

The problem of having to sample multiple subsamples from large volumes to accurately assess low 

densities of organisms is compounded by aggregated distributions (Figure C-2). In the comparison given 

in Lee et al. (2010), for a randomly distributed population with a true concentration of 1 zooplanktonsized organism m-3

, ~37% of the subsamples from a 1 m3 sample of treated ballast water would contain 

zero zooplankton-sized organisms. For an aggregated population with a dispersion parameter of 0.1, 

however, ~79% of the subsamples would contain zero organisms (Figure C-2). The relationship between 

the probability of finding zero organisms in a sample and the amount of aggregation is also illustrated 

(Fig. C-3) for the concentration of 1 organism m-3. As variance (σ

2

) increases, the dispersion parameter θ 

Figure C-1. Determining whether ballast water discharge exceeds or meets a performance standard of < 

0.01 (A) and <10 (B) organisms m-3 (note: axes have different scales). Red regions indicate total 

organism counts that exceed the standard. Green regions indicate total organism counts that meet the 

standard. White regions indicate indeterminate results; counts in this region do not pass or fail inspection 

based on two-tailed 95% confidence intervals. (Source: Lee et al. 2010). 
C-8

decreases, indicating more aggregation, with increasing probability of finding no organisms in a sample. 

With more aggregation, the probability of samples containing large numbers of organisms relative to the 

true concentration also increases. Thus, large numbers of subsamples from large sample volumes must 

be taken to account for aggregated populations; otherwise, there will be a high probability that the 

concentration estimates from sample analyses will be either much lower or much higher than the true 

concentration.

Figure C-2. Comparison of sample probabilities from a randomly distributed population (Poisson distribution) vs. an 

aggregated population with a dispersion parameter of 0.1 (negative binomial distribution) for a sample volume of 1 m3 and 

concentration of 1 organism m-3

. For low organism numbers (3 or fewer m-3), the probability that a sample will contain zero 

organisms tends to be much greater for the aggregated population. (Source: Lee et al. 2010).

Figure C-3. The probability of finding zero organisms in a sample volume of 1 m3 and concentration of μ = 1 organism m-3. 

The probability of 0 organisms = (1 + θ)-θ

, where dispersion parameter θ = 1/(σ2 – 1). When σ2 = 1.0, organisms are randomly 

distributed, at which the probability of 0 organisms in the sample = 0.37 (Poisson distribution) (Elliott 1971).
C-9

Determination of whether a population is aggregated is complicated, since it is the scale of the 

aggregation pattern relative to the size of the sampling unit that controls the estimate of aggregation 

(Fig. C-3). If organisms form clumps that are randomly distributed, the population may be highly 

aggregated, but in a small sample volume containing 0 or 1 organisms, the population will appear 

randomly distributed or only slightly aggregated. With increasing sample volume, the variance in the 

number of organisms increases in comparison to the mean, and maximum variance is encountered when 

the sample volume is equal to the volume of a single cluster of organisms (Elliott 1971). For larger 

sample volumes, a sample unit will include several clusters, so the variance decreases in comparison to 

the mean and the observations will approach a Poisson distribution. Lee et al. (2010) recommend the 

Taylor power law (Taylor 1961) as an alternative to the negative binomial, because it can accommodate 

a wider range of aggregated distributions than the negative binomial. 

Overall, the possibility for and degree of aggregation represent challenges in sampling sufficiently large 

volumes of ballast water to determine whether a given BWMS passes or fails to meet standards more 

stringent than the present IMO guidelines, even if the true concentrations of organisms are 10 to 1,000

times higher than the performance standard. This remains a problem in quantifying many protist-sized 

organisms, but becomes less of a problem with very small organisms such as bacteria, which have a 

tendency to clump but are effectively counted as colonies and not individuals. However, in Lemieux et 

al. (2008), data from protist-sized microbeads at various concentrations were analyzed and 

concentrations of 100 mL-1 and lower were found to adhere to a Poisson distribution. The flasks of 

microbeads were well mixed, as would be samples of ballast water collected from the sample ports and 

collected to be representative of the entire volume sampled (e.g., over the entire discharge operation of 

the tank). Likewise, monocultures of protists in low densities (~10 to 30 mL-1) adhered to a Poisson 

distribution (Nelson et al. 2009). These data lend support to using the Poisson distribution to analyzed 

ballast water samples.