Review - EPA’s Worst-Case Discharge NPRM – Substantial Harm

This is the next post in my series on the recent notice of proposed rulemaking (NPRM) from the EPA for “Clean Water Act Hazardous Substance Worst Case Discharge Planning Regulations”. Earlier posts in this series were:

EPA Publishes Worst Case Discharge NPRM (Subscription version)

EPA’s Worst-Case Discharge NPRM – Affected Facilities (Subscription version)

Substantial Harm Requirement

Any facility that meets the threshold quantity and proximity to navigable waters screening thresholds of the rule then needs to determine if they meet the substantial harm standards that would lead to the facility being subject to the worst-case discharge planning requirements. Facilities meet the substantial harm standards if they fill any one of the following conditions:

• Ability to cause injury to fish, wildlife, and sensitive environments (FWSE),

• Ability to adversely impact a public water system,

• Ability to cause injury to public receptors, or

• Reportable discharge history

Alternative Methodologies

While the NPRM provides specific methodologies for determining if a facility meets one or more of the ‘substantial harm requirements’, the EPA has identified some alternative methods for making those determinations. The EPA provides a discussion for each of those alternatives and is seeking public comment on those procedures. The alternatives include:

• Alternative toxic end point methods discussed here and here,

• Determining public water system affects discussed here and here, and

• Determining a reportable discharge quantity that are discussed here, here, and here.