Evolving Scope of
the U.S. Clean
Water Act
Caitlyn Johnson
ENCE412 Spring 2023
Introduction and
Contents
About Me
• B.S. Civil and Environmental
Engineering Water Resource
Management
• Minor Global Engineering
Leadership
• Post Grad: MK Consulting
Engineers
• Sustainable Urban Design
About the Paper
• History
• Case Study
• Methods
• Results
• Conclusion
• Applications
History
1948-1972
1972-1982
1982-2006
2006- Present
• Federal Water
Pollution
Control Act
• Aimed to
protect
human health
• “interstate
waters”
• Poor
enforcement
• 1961
Amendments;
Water Quality
Act
• Clean Water
Act
• WOTUS
• Vague
legislative
definition
• USACE and
USEPA
regulation
• Wetlands
• Prompted
Supreme
Court
rulings
• Ruled out
isolated
wetlands
and
waterways
• Clear limits
on CWA
protection
• Rapanos v.
US
• “significant
nexus”
• 2015 Clean
Water Rule
(CWR)
• 2020
Navigable
Water
Protections
Rule
(NWPR)
Methods
Case Study:
Wabash River
Basin, IL,IN,OH,
USA
• Critically examine timeline of
Federal Regulations, court cases,
and laws and amendments
• Define jurisdictional WOTUS
• Display over time what streams,
lakes, and wetlands are:
• Protected
• Possibly
• Conditionally
• Not Protected
Case Study: Results
Conclusions
Uncertainty in which waters are
jurisdictional has remained high
Supreme court cases and agency rules often
shift uncertainty rather than clarifying
Modern changes, NWPR and CWR, have had
small impacts
Applications
Geospatial analysis to evaluate policy
implications
Observing historic changes to WOTUS can
inform modern rulemaking
Agencies need to clarify which waters should be regulated
Some uncertainty allows state and local agencies to adopt rules that best fit
Hydrologists predictions and mitigations rely on clear regulations and relevant
data