Prioritization Framework for Technical
Cybersecurity Support to Public Water
Systems — Report to Congress


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Contents

Contents

Executive Summary

Statutory Requirements forthis Report

Consideration of the National Critical
Infrastructure Prioritization Program

Possible use of a Prioritization Framework
for Technical Cybersecurity Support

Prioritization Framework Goals

Prioritization Framework

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EXECUTIVE SUMMARY

TheInfrastructureInvestmentandJobsAct(PublicLawNo. 117-58) requires theU.S. Environmental
Protection Agency (EPA), in coordination with the Cybersecurity and Infrastructure Security Agency
(CISA), to develop a Prioritization Framework to identify public water systems (including sources of
water for those public water systems) that, if degraded or rendered inoperable due to an incident,
would lead to significant impacts on the health and safety of the public. EPA, in coordination with
CISA, is to use the Prioritization Framework to develop a Technical Cybersecurity Support Plan for
public water systems.

In developing the Prioritization Framework, EPA must incorporate consideration of four criteria: (1)
whether cybersecurity vulnerabilities for a public water system have been identified under Section
1433 of the Safe Drinking Water Act (SDWA), (2) the capacity of a public water system to remediate
a cybersecurity vulnerability without additional Federal support, (3) whether a public water system
serves a defense installation or critical national security asset, and (4) whether a public water system,
if degraded or rendered inoperable due to an incident, would cause a cascading failure of other
critical infrastructure.

Finally, EPA must submit to the appropriate Congressional committees a report describing the
Prioritization Framework not later than May 24, 2022. This report was prepared in fulfillment of
this requirement.

The Prioritization Framework is structured as a series of qualitative questions stemming from the
statutory criteria. This structure will provide EPA and CISA with the necessary flexibility to tailor the
prioritization of water systems for technical cybersecurity support to specific circumstances and
water system needs.

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STATUTORY REQUIREMENTS FOR THIS REPORT

The Infrastructure Investment and Jobs Act (the Act) became Public Law No. 117-58 on November 15,
2021. Section 50113 of the Act amends Part B of the SDWA (42 U.S.C. 300g et seq.) by adding at the
end the following: Section 1420A. Cybersecurity Support for Public Water Systems.

Subsection (b)(1) of this section requires EPA, in coordination with CISA, to develop a Prioritization
Framework within 180 days of the Act's enactment to identify public water systems (including
sources of water for those public water systems) that, if degraded or rendered inoperable due to an
incident, would lead to significant impacts on the health and safety of the public.

Subsection (b)(2) specifies that EPA, in coordination with CISA, is to use the Prioritization Framework
to develop a Technical Cybersecurity Support Plan for public water systems within 270 days of the
Act's enactment. In alignment with the deadlines specified in the statute, this report addresses
the Prioritization Framework only. The Technical Cybersecurity Support Plan will be provided in a
subsequent report.

In developing the Prioritization Framework, EPA must incorporate consideration of the following
four criteria to the extent practicable (paragraph (b)(1)(B) of this subsection):

(1)	whether cybersecurity vulnerabilities for a public water system have been identified under
Section 1433 of the SDWA

• Note: SDWA Section 1433 requires community water systems serving over 3,300 people
to develop a risk and resilience assessment, which must include electronic, computer, or
other automated systems, and an emergency response plan that must include strategies
and resources to improve...the cybersecurity of the system.

(2)	the capacity of a public water system to remediate a cybersecurity vulnerability without
additional Federal support,

(3)	whether a public water system serves a defense installation or critical national security
asset, and

(4)	whether a public water system, if degraded or rendered inoperable due to an incident,
would cause a cascading failure of other critical infrastructure.

Further, EPA must consult with such Federal or non-Federal entities as determined to be
appropriate by the Administrator (paragraph (b)(3) of this subsection). To fulfill this requirement,
EPA established a workgroup with the Water Sector Coordinating Council, Water Government
Coordinating Council, and CISA (hereinafter, the workgroup). This workgroup held initial meetings
to discuss proposed approaches to the Prioritization Framework and, subsequently, to review draft
versions of this report.

Finally, EPA must submit to the appropriate Congressional committees a report describing the
Prioritization Framework not later than 190 days after the date of enactment of the Act. Hence, the
statutory due date for this Prioritization Framework report is May 24, 2022.

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CONSIDERATION OF THE NATIONAL CRITICAL
INFRASTRUCTURE PRIORITIZATION PROGRAM

EPA and the workgroup considered whether existing prioritization criteria could fulfill the
requirements of the Act. The Department of Homeland Security (DHS) maintains a classified list
of critical infrastructure systems and assets that "would, if destroyed or disrupted, cause national
or regional catastrophic effects." This list was developed and is maintained through the National
Critical Infrastructure Prioritization Program (NCIPP).

Under the NCIPP, qualifying domestic infrastructure may be designated as Level 1 or 2 based on the
projected impact of an adverse event, such as an industrial accident, natural disaster, or malicious
act (e.g., cyber-attack). For all critical infrastructure sectors, including water but excluding food and
agriculture, a facility or system is assigned as Level 1 or 2 if a disruption would result in at least two of
the following consequences:

¦	Greater than 5,000 (Level 1) or 2,500 (Level 2) prompt fatalities,

¦	Greater than $75 billion (Level 1) or $25 billion (Level 2) in first-year economic consequences,

¦	Mass evacuations with a prolonged absence of greater than three months (Level 1) or 1 month
(Level 2) and/or,

¦	Severe degradation of the Nation's national security capabilities, including intelligence and defense
functions, but excluding military facilities.

Alternatively, a facility or system may be assigned to the list based on a first-year economic impact
of $150 billion or more (Level 1) or at least $50 billion (Level 2). For water systems, contamination,
intentional or otherwise, is not a permitted scenario.

The number of public water systems that meet these criteria and are designated as level 1 or 2
under the NCIPP is well below one percent of all water systems in the sector. Further, the NCIPP
criteria have the effect of selecting the largest water systems, which typically have the most
resources to address cybersecurity vulnerabilities. Consequently, the criteria for Level 1 and 2 facilities
under the NCIPP would not be effective for the purposes of the Prioritization Framework under the
Act, which is to prioritize technical cybersecurity support across the entire water sector. Accordingly,
EPA did not use the NCIPP criteria in the Prioritization Framework

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POSSIBLE USE OF A PRIORITIZATION FRAMEWORK
FOR TECHNICAL CYBERSECURITY SUPPORT

Both EPA and CISA currently offer ongoing technical cybersecurity support to public water systems
through programs such as EPA's Cybersecurity Technical Assistance Provider Program and CISA's
Cyber Hygiene Services. The Technical Cybersecurity Support Plan report, which EPA will develop
pursuant to the Act following this report, will describe these programs in detail.

In addition, when a situation occurs that creates an elevated cyber risk level, such as knowledge
of a significant cyber vulnerability or new cyber threat, EPA and CISA work with Federal and
state government partners, WaterlSAC, and water sector associations to assist water systems
with undertaking mitigation actions. This assistance may comprise of alerts, webinars, and direct
outreach to watersystems.

Technical cybersecurity support from EPA and CISA is provided to water systems upon request.
Receipt of this support by a water system is voluntary. To date, EPA and CISA have been able to
provide requested technical cybersecurity support to water systems without delay. Consequently,
a prioritization framework for delivering technical cybersecurity support to water systems has not
factored into EPA or CISA's technical assistance efforts.

The Prioritization Framework described in this report could potentially be used under a scenario
in which many water systems require technical cybersecurity support at the same time. Such
a scenario might involve, for example, the discovery of a widespread zero-day vulnerability (i.e.,
a vulnerability in a system or device that has been disclosed but not yet patched) that impacts
numerous water systems and that many water systems lack the technical capability to correct
without assistance. If EPA or CISA were unable to assist all water systems that require help in a
timely manner, then this Prioritization Framework could be employed to determine the order in
which water systems receive support.

PRIORITIZATION FRAMEWORK GOALS

Based on workgroup discussions, EPA identified several goals for the Prioritization Framework:

¦	Flexible structure: As discussed above, use of the Prioritization Framework may be most useful in
circumstances resulting in requests for technical cybersecurity support that exceed the near-term
capacity of EPA or CISA. Thus, the Prioritization Framework should be highly flexible so that EPA or
CISA can tailor it to meet the risks and demands of exigent circumstances.

¦	Allow consideration of individual water system circumstances: Under the conditions where the
Prioritization Framework might be used, the risks, capabilities, resources, needs, and other factors
that impact the response of the water sector to the situation will vary widely among water systems.
The Prioritization Framework should allow EPA or CISA to consider the circumstances of individual
water systems.

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¦	Compatible with dynamic cybersecurity technical support capabilities of EPA and CISA: The
technical cybersecurity support that EPAand CISA offer to water systems will evolve in response
to changing threat conditions, resources, and the requests of the water sector. Accordingly, the
Prioritization Framework should accommodate the dynamic nature of EPA and CISA's capabilities.

¦	incorporate statutory criteria: The Prioritization Framework should incorporate, to the extent
practicable, the four criteria listed in the statute in a manner compatible with the other goals listed
here. Consequently, the use of a particular criterion and the weight accorded to it in a prioritization
scenario may vary based on the circumstances.

¦	Environmental justice: The Prioritization Framework should provide for fair treatment of all people
regardless of race, color, national origin, or income, with respect to technical cybersecurity support.

PRIORITIZATION FRAMEWORK

The Prioritization Framework is structured as a series of qualitative questions stemming from the
statutory criteria. This qualitative structure will provide EPA and CISA with the necessary flexibility
to tailor the prioritization of water systems for technical cybersecurity support to specific threat
circumstances and water system needs.

The Framework is not designed to assign a water system to a fixed prioritization rank
independent of a scenario where prioritization is needed. Rather, it reflects the understanding
that decisions on prioritizing water systems for technical cybersecurity support would depend on
the circumstances of a particular scenario (e.g., the type of cybersecurity vulnerability and technical
support required, the number of water systems requesting assistance, and the capacity of EPA or
CISA to deliver support).

As described above, existing circumstances have not required either EPA or CISA to use a
prioritization framework for technical cybersecurity support to date. Should the need for a
prioritization framework arise in the future, the Framework offered here could be adjusted
as needed.

Under the Prioritization Framework, a water system requesting technical cybersecurity support
during a surge scenario (i.e., a scenario where demand for technical cybersecurity support from EPA
or CISA exceeds the near-term capacity of the Agency) would respond to the Framework questions.
The Agency (EPA or CISA in coordination with EPA) providing the technical support would
determine the appropriate prioritization order based on the water system responses and the totality
of the circumstances, such as:

¦	The risk to water system operations and potential adverse impacts on the service area, downstream
critical infrastructure, and defense/national security assets,

¦	The capabilities of a water system to remediate the vulnerability without Federal support, and

¦	The risk reduction benefits that technical cybersecurity support from CISA or EPA would achieve.

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Table 1 below lists the required statutory criteria for the Prioritization Framework, the associated
questions that a water system would answer when requesting cybersecurity technical support
under a surge scenario where use of the Framework was needed, and considerations that EPA or
CISA could apply when determining a prioritization order.

Note that the order in which the criteria are listed in Table 1 does not imply preferential weighting
for prioritization rank. Rather, weighting would be based on the threat circumstances and the
needs of water systems for technical cybersecurity support.

Table 1: PRIORITIZATION FRAMEWORK CRITERIA, QUESTIONS, AND AGENCY CONSIDERATIONS

Statutory criteria
from Sec. 1420A(b)(l)

Questions for water systems requesting
technical cybersecurity support

Considerations by EPA or CISA in
prioritizing water systems for assistance

(A)...identify public
water systems
(including sources
of water for those
public water
systems) that,
if degraded or
rendered inoperable
due to an incident,
would lead to
significant impacts
on the health and
safety of the public

How many people does the water
system or source serve (including
consecutive systems and those
technologically integrated)?

Does the service area have resources
(e.g., alternative sources of supply) that
could mitigate the impact of degraded
water service?

Note: Downstream critical
infrastructure, such as health care, is
addressed in a separate criterion.

Priority would increase with greater
population served (i.e., adverse impacts
from water service degradation would grow
with higher population served).

Priority would decrease for water
systems where the service area has greater
resources to mitigate impacts of degraded
water service.

(B)(i) whether
cybersecurity
vulnerabilities for a
public water system
have been identified
under Section 1433

Did the water system conduct a risk
and resilience assessment under
America's Water Infrastructure Act that
included cybersecurity (required for
community water systems serving over
3,300 people)?

Did the water system conduct an
alternative cybersecurity vulnerability
assessment (e.g., CISA Cyber Hygiene
services, EPA Technical Assistance
Provider program, NIST Cybersecurity
Framework, or private sector
assessment)?

Whether a water system had
conducted a cybersecurity vulnerability
assessment would not be a factor in
decisions by EPA or CISA to provide
critical technical cybersecurity support.

If a water system reported that it had
identified a vulnerability under an
assessment but had not yet addressed
the vulnerability, EPA or CISA would
consider whether that vulnerability
would increase the need for assistance
under the threat circumstance.

Regardless of priority, EPA and CISA
would encourage the water system to
correct the deficiency and would assist
the water system where needed.

Furthermore, if a water system requested
technical cybersecurity support and had
not assessed cybersecurity vulnerabilities,
EPA and CISA would, in addition to
providing the requested support,
encourage the water system to do so and
would assist the water system where
needed.

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Statutory criteria
from Sec. 1420A(b)(l)

Questions for water systems requesting
technical cybersecurity support

Considerations by EPA or CISA in
prioritizing water systems for assistance

(B)(ii) the capacity
of a publicwater
system to remediate
a cybersecurity
vulnerability without
additional Federal
support

What near- and long-term internal
technical capabilities and financial
resources does the water system have
to correct cybersecurity
vulnerabilities?

How urgent is the water system's
need for technical cybersecurity
assistance?

Are other external sources of technical
cybersecurity support (e.g., other
government or private sector
assistance providers) available to the
water system?

A water system with an urgent need for
technical cybersecurity support (e.g., a
known vulnerability that poses a significant
risk to the water system's operations)
and that lacks either internal or external
technical or financial resources to correct
the vulnerability in a sufficient time frame
would be prioritized for assistance.

(B)(iii) whether a
public water system
serves a defense
installation or critical
national security
asset

Does the water system serve a defense
installation or national security asset
(e.g., defense production facility,
communications provider, etc.)?

Serving a defense installation or national
security asset would be a significant
prioritization factor for technical
cybersecurity support.

(B)(iv) whether a
public water system,
if degraded or
rendered inoperable
due to an incident,
would cause a
cascading failure
of other critical
infrastructure

What critical infrastructure facilities
does the water system serve (across a!!
16 critical infrastructure sectors)?

Water systems that serve a greater number
of critical infrastructure facilities would
be prioritized for technical cybersecurity
support.

Further, water systems that serve critical
infrastructure facilities where a degradation
in water service would cause especially
severe consequences (e.g., health care
facilities) would be prioritized for support

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