Transforming Urban Water Initiative

From Gray to Green Shorelines

Regulatory Pathways for Nature-based Solutions  

This project is a close collaboration between regulators, project proponents and technical experts. The primary objectives are:  

  • Develop case studies of NBS and/or horizontal levee projects, the key tradeoffs associated with them (habitat, water quality, public access, etc.), and the impacts that regulatory directives have on design and implementation.  
  • Identify permitting challenges for NBS and horizontal levee projects, including initial permitting barriers, regulatory requirements that make projects cost prohibitive and/or high risk for project proponents, and regulatory constraints for long-term operations and maintenance.  
  • Identify potential regulatory and permitting pathways for NBS and horizontal levee projects to address the identified challenges. If current pathways exist, identify recommendations for possible improvements.  
  • Complete an analysis that summarizes key findings and recommendations.  

For more information, contact Heid Nutters (  

Key Project Resources

Regulatory Pathways for Nature-based Solutions White Paper: This white paper is intended for use by organizations working toward sea level rise (SLR) solutions and regulatory agencies, to promote discussion and elevate opportunities to advance NbS projects in the San Francisco Bay Area (Bay Area). Published October, 2023. Read here

Regulatory Call for Accelerating Action Memo: Coming Winter 2023! 

Project Case Studies: These case studies highlight local NbS projects and explores some of the permitting pathways considered. 

  1.  Palo Alto Horizontal Levee (Published June 2023) 
  2.  Hayward Nature-based Solutions Feasibility Study (Published June 2023) 
  3.  First Mile Horizontal Levee (Published June 2023) 
  4. Sonoma Creek Marsh Enhancement Project (Published June 2023)

Project Team:

  • Jill Sunahara (Enviromental Science Associates)
  • Heidi Nutters (SF Estuary Partnership)
  • Jen Siu (US Environmental Protection Agency)

Project Advisors:

  • Caitlin Sweeney, SF Estuary Partnership
  • Luisa Valiela, Sahrye Cohen, US Environmental Protection Agency
  • Ethan Lavine, Dominic Maccormack, SF Bay Conservation and Development Commission
  • Xavier Fernandez, SF Bay Regional Water Quality Control Board
  • Jackie Zipkin, East Bay Dischargers Authority
  • Jeremy Lowe, SF Estuary Institute