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Our Plan and Process

The One Water Honolulu Plan is grounded in the idea that adapting to and reducing climate risks requires collaboration—no one City department can do this alone. It envisions a future where water is managed not as separate systems, but as one connected resource, mauka to makai, to protect what sustains life on O’ahu.

Read the One Water Honolulu Plan
Circular diagram illustrating the One Water Honolulu framework. At the center is One Water Honolulu, surrounded by five overlapping planning areas: Water (Water Master Plan, Watershed Management Plans, Source Water Protection Plan), Wastewater (Wastewater Facility Plans and Water Recycling Program), Storm Water (Storm Water Master Plan and Green Infrastructure Implementation Plan), Hazard Planning (Local Hazard Mitigation Plans and Development Plans and Sustainable Communities Plans), and Climate Change (Climate Ready Oʻahu, Oʻahu Resilience Strategy, and Climate Action Plan). An outer ring labeled "One Water Solutions" connects all planning areas.

A Resilience Roadmap

The Plan supports implementation of the City and County of Honolulu’s Climate Ready O’ahu strategy to prepare and safeguard people, ʻāina, and infrastructure by providing a holistic water management plan and a 30-year list of multi-benefit projects to build resilience in our island’s infrastructure and natural systems.

The One Water Plan is a collaborative roadmap that focuses on how to implement the resilience strategy, recognizing that most climate impacts involve water—too much or too little of it.

Dive into O’ahu’s Water story

Collaboration Framework

The Plan establishes a structured approach for action-oriented solutions and joint decision-making, recognizing that climate change impacts can only be addressed by working together across City and state agencies, landowners, developers, organizations, consultants, and the community.

  • Shared Responsibility: Bring together City and state agencies, large landowners, developers, organizations, consultants, and the community to collaboratively mitigate climate change impacts and build lasting resilience.
  • Institutionalized Collaboration: Anchor the framework in Ordinance 20-47, which formally established collaboration as essential to achieving climate resilience.
  • One Water Panel: Continued coordination among the panel of eight City Departments to coordinate action, align priorities, and guide implementation across agencies.
  • Long-Term Continuity: Extend progress across future administrations, ensuring continuity in purpose and durable, long-term results.

Climate Change Adaptation Framework

The Plan screens the island’s water infrastructure for exposure to climate hazards — from flooding and sea level rise to drought and wildfire — to pinpoint where risks are greatest and where investment is needed most.

500,000+ assets evaluated → Top 0.5% screened as most vulnerable → 92 geographic hotspots identified → 14 Priority Hotspots selected
  • Climate Risk Screening: Evaluate more than 500,000 water, wastewater, and stormwater infrastructure assets using GIS mapping, identifying the top 0.5% most vulnerable water infrastructure.
  • Known Areas of Concern: Combine technical analysis with existing City and community knowledge—previous planning efforts, stakeholder engagement, existing project ideas, adaptive capacity, and input from the One Water Panel and Leadership Group—to identify local issues and community concerns.
  • Hotspot Identification: Group at-risk infrastructure and known concerns into geographic areas where climate adaptation or risk intervention may be most urgent, identifying 92 geographic hotspots for additional evaluation and prioritization.
  • Priority Hotspots: Identify 14 Priority Hotspots across O’ahu through the Climate Hotspot Identification Process, providing a foundation for future project identification and prioritization.

One Water Projects

Building on the 14 Priority Hotspots, the Plan translates regional priorities and climate risk results into tangible action. Through a collaborative process, it develops goals, strategies, and a set of 49 near-, mid-, and long-term projects that guide a more resilient O’ahu.

  • Regional Priorities & Risk Results: Translate the climate risk findings and regional priorities from each Priority Hotspot into a foundation for locally tailored planning.
  • Collaborative Development: Work with City departments, partners, and communities to shape goals, adaptation strategies, project concepts, policies, and actions for each priority location identified around the island.
  • Resilience Goals: Organize goals around three core themes — People (empowered and prepared people), ʻĀina (safeguarded and stewarded ʻāina, including the management of wai), and Infrastructure (safe and reliable systems) — ensuring project development reflects the resilience goals championed across City policies and programs.
  • Defined Projects: Identify 49 near-, mid-, and long-term projects across Oʻahu, providing a clear roadmap from planning to action. The full list can be found in Section 7 of the One Water Honolulu Plan.

One Water Honolulu Planning Timeline

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