33 CFR 151.1511: Ballast water discharge standard
Last reviewed: October 14, 2026
This section sets the ballast water discharge standard (BWDS) for vessels that use a Coast Guard-approved ballast water management system (BWMS). It limits living organisms and indicator microorganisms in discharged ballast water. It also describes a Coast Guard practicability review of more stringent standards.
Applies toVessels employing a Coast Guard-approved ballast water management system (BWMS).
What it says
Vessels employing a Coast Guard-approved BWMS must meet the BWDS by the date in § 151.1512(b) of this subpart.
33 CFR 151.1511(a)“Vessels employing a Coast Guard-approved ballast water management system (BWMS) must meet the following BWDS by the date in § 151.1512(b) of this subpart:”
Discharge of organisms greater than or equal to 50 micrometers in minimum dimension must include fewer than 10 living organisms per cubic meter of ballast water.
33 CFR 151.1511(a)(1)“For organisms greater than or equal to 50 micrometers in minimum dimension: discharge must include fewer than 10 living organisms per cubic meter of ballast water.”
Discharge of organisms less than 50 micrometers and greater than or equal to 10 micrometers must include fewer than 10 living organisms per milliliter (mL) of ballast water.
33 CFR 151.1511(a)(2)“For organisms less than 50 micrometers and greater than or equal to 10 micrometers: discharge must include fewer than 10 living organisms per milliliter (mL) of ballast water.”
Toxicogenic Vibrio cholerae (serotypes O1 and O139) must be at a concentration of less than 1 colony forming unit (cfu) per 100 mL.
33 CFR 151.1511(a)(3)(i)“For Toxicogenic Vibrio cholerae (serotypes O1 and O139): a concentration of less than 1 colony forming unit (cfu) per 100 mL.”
Escherichia coli must be at a concentration of fewer than 250 cfu per 100 mL.
33 CFR 151.1511(a)(3)(ii)“For Escherichia coli: a concentration of fewer than 250 cfu per 100 mL.”
Intestinal enterococci must be at a concentration of fewer than 100 cfu per 100 mL.
33 CFR 151.1511(a)(3)(iii)“For intestinal enterococci: a concentration of fewer than 100 cfu per 100 mL.”
The Coast Guard will publish the results of a practicability review no later than January 1, 2016, on whether technology and testing protocols for a more stringent standard can be practicably implemented.
33 CFR 151.1511(c)(1)“No later than January 1, 2016, the Coast Guard will publish the results of a practicability review to determine—”
Common questions
What is the limit for E. coli in discharged ballast water?
Escherichia coli must be at a concentration of fewer than 250 cfu per 100 mL.
“For Escherichia coli: a concentration of fewer than 250 cfu per 100 mL.”
Who must meet the ballast water discharge standard in this section?
Vessels employing a Coast Guard-approved BWMS must meet it by the date in § 151.1512(b) of this subpart.
“Vessels employing a Coast Guard-approved ballast water management system (BWMS) must meet the following BWDS by the date in § 151.1512(b) of this subpart:”
What is the limit for organisms 50 micrometers or larger in ballast water discharge?
Discharge must include fewer than 10 living organisms per cubic meter of ballast water.
“For organisms greater than or equal to 50 micrometers in minimum dimension: discharge must include fewer than 10 living organisms per cubic meter of ballast water.”
The text of 33 CFR 151.1511
Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR
Ballast water discharge standard (BWDS)
(a) Vessels employing a Coast Guard-approved ballast water management system (BWMS) must meet the following BWDS by the date in § 151.1512(b) of this subpart:
(1) For organisms greater than or equal to 50 micrometers in minimum dimension: discharge must include fewer than 10 living organisms per cubic meter of ballast water.
(2) For organisms less than 50 micrometers and greater than or equal to 10 micrometers: discharge must include fewer than 10 living organisms per milliliter (mL) of ballast water.
(3) Indicator microorganisms must not exceed:
(i) For Toxicogenic Vibrio cholerae (serotypes O1 and O139): a concentration of less than 1 colony forming unit (cfu) per 100 mL.
(ii) For Escherichia coli: a concentration of fewer than 250 cfu per 100 mL.
(iii) For intestinal enterococci: a concentration of fewer than 100 cfu per 100 mL.
(b) [Reserved]
(c) The Coast Guard will conduct a practicability review as follows:
(1) No later than January 1, 2016, the Coast Guard will publish the results of a practicability review to determine—
(i) Whether technology to comply with a performance standard more stringent than that required by paragraph (a) of this section can be practicably implemented, in whole or in part, and, if so, the Coast Guard will schedule a rulemaking to implement the more stringent standard; and
(ii) Whether testing protocols that can accurately measure efficacy of treatment against a performance standard more stringent than that required by paragraph (a) of this section can be practicably implemented.
(2) If the Coast Guard determines on the basis of a practicability review conducted under paragraph (c)(1) of this section that technology to achieve a significant improvement in ballast water treatment efficacy could be practicably implemented, the Coast Guard will report this finding and will, no later than January 1, 2017, initiate a rulemaking that would establish performance standards and other requirements or conditions to ensure to the maximum extent practicable that aquatic nuisance species are not discharged into waters of the United States from vessels. If the Coast Guard subsequently finds that it is not able to meet this schedule, the Coast Guard will publish a notice in the Federal Register so informing the public, along with an explanation of the reason for the delay, and a revised schedule for rule making that shall be as expeditious as practicable.
(3) When conducting the practicability review as required by paragraph (c)(1) of this section, the Coast Guard will consider—
(i) The capability of any identified technology to achieve a more stringent ballast water discharge standard, in whole or in part;
(ii) The effectiveness of any identified technology in the shipboard environment;
(iii) The compatibility of any identified technology with vessel design and operation;
(iv) The safety of any identified technology;
(v) Whether the use of any identified technology may have an adverse impact on the environment;
(vi) The cost of any identified technology;
(vii) The economic impact of any identified technology, including the impact on shipping, small businesses, and other uses of the aquatic environment;
(viii) The availability, accuracy, precision, and cost of methods and technologies for measuring the concentrations of organisms, treatment chemicals, or other pertinent parameters in treated ballast water as would be required under any alternative discharge standards;
(ix) Any requirements for the management of ballast water included in the most current version of the U.S. Environmental Protection Agency's Vessel General Permit and any documentation available from the EPA regarding the basis for these requirements; and
(x) Any other factor that the Coast Guard considers appropriate that is related to the determination of whether identified technology is performable, practicable, and/or may possibly prevent the introduction and spread of non-indigenous aquatic invasive species.
Sections it refers to
The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.