No Adverse Impact Legal Guide

The No Adverse Impact Legal Guide website was developed to make it easier for floodplain administrators to find answers to common legal questions; learn about essential legal concepts related to flood risk management; and provide relevant legal memos, case law, and analysis for their community attorneys.

As a floodplain administrator…

• Start with the Common Floodplain Management Legal Questions section below. The answers are written with you in mind but also provide specific references to legal memos and analysis (Section III, IV, V) to share with your attorney.
• Next, look at the sections titled "Introduction to NAI" and "Introduction to Legal Concepts for NAI" for a deeper dive into understanding NAI and its related legal concepts.

The Guide helps floodplain administrators understand legal issues that may arise when a community implements activities that enhance flood resilience, especially when those activities exceed state and federal floodplain management requirements.

This Guide supplements other NAI resources, tools, and guidance that share ways of integrating NAI principles into local regulations, policies, and programs.

Common Floodplain Management Legal Questions

Q1. Do floodplain regulations, higher standards, or No Adverse Impact (NAI) requirements expose communities to takings claims or other property rights challenges?

Q2. How can No Adverse Impact (NAI) approaches be clearly defined, applied consistently, and defended legally?

Q3. How much legal liability do communities and floodplain managers face for permitting development in flood hazard areas, including liability for downstream or cumulative impacts?

Q4. What legal authority can communities use to regulate development based on future conditions like anticipated build-out, sea-level rise, climate change, post-fire flooding, and aging infrastructure?

Q5. What liability exists when floodplain managers rely on sealed engineering studies, elevation certificates, or FEMA-approved analyses that later prove inadequate?

Q6. What legal protections exist for floodplain managers facing personal liability, retaliation, or professional risk for enforcing regulations?

Q7. Are communities legally vulnerable for allowing floodway encroachments or development that increases BFEs, even when mitigation or no-rise certificates are provided?

Q8. What legal risks arise from floodplain map revisions, new floodway delineations, or updated flood studies that affect previously approved development?

Q9. Can communities be held responsible if they repeatedly allow code-compliant rebuilding in floodplains if it increases actual long-term risk?

Q10. How should conflicts among different programs (e.g., NFIP), federal agencies (e.g., HUD), state laws, building codes, and environmental regulations be resolved to minimize legal risk?

Questions 1-10 Collated.

No Adverse Impact Legal Guide

Use this link to view/download the entire NAI Legal Guide:

This Guide is divided into five sections that can be viewed/downloaded individually using the links below.

• Section I – Introduction to No Adverse Impact
  • I.A. Local Implementation of NAI
  • I.B. A Legal Foundation for NAI
  • I.C. The National Flood Insurance Program (NFIP)
  • I.D. Limitations of Minimum NFIP Standards
  • I.E. The NAI Approach
• Section II – Introduction to Legal Concepts for No Adverse Impact
  • II.A. Lawsuits
  • II.B. Venue – state courts, federal district courts, and federal court of claims
  • II.C. Property
  • II.D. Sovereign Submerged Land
  • II.E. Land Use Limitations
• Section III – Torts
  • III.A. Negligence
  • III.B. Trespass to Land
  • III.C. Nuisance
  • III.D. Governmental and Sovereign Immunity from Liability
• Section IV – The Constitution and Its Protection of Property Rights
  • IV.A. Fourteenth Amendment
  • IV.B. Fifth Amendment
  • IV.C. Summary of Takings
• Section V – Federal Laws
  • V.A. Generally
  • V.B. Executive Orders: Floodplain Stewardship

Section One is an introduction to the concept of No Adverse Impact for those not familiar with its application to flood risk reduction. Section Two focuses on introducing common legal concepts, which is then followed by the detailed legal memos found in Sections Three, Four and Five.

After reviewing this Guide, it is recommended that a community conduct an assessment of its flood risk management activities to see if those activities are legally sound, and where they can be improved by using NAI techniques to better protect its population and natural floodplain functions.