Project Lead

County of Maui Department of Public Works

Project Website

Project Type

Infrastructure

Natural Resources & Environment

Plan Alignment

Lahaina LTRP

One Water Lahaina (OWL)

Funding Sources

EPA

USDA Natural Resources Conservation Service (NRCS)

Brief Description:

Improve stormwater and flood management in West Maui by updating drainage plans, reducing runoff into the ocean, and developing flood control improvements in Lahaina.

Milestones:

Drainage Master Plan Update:

August 2025: EPA completed the Lahaina Green Stormwater Infrastructure Drainage Supplement to the Lahaina Drainage Master Plan.

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Lahaina Watershed Flood Protection Project (LWFPP):

Technical studies are under way for the planning and preliminary design. Environmental review and public comment process will begin Summer 2026.

Project Location:

“Incentivize 100% stormwater control and infiltration (with simple vegetative swales) to eliminate brown water events that impact our reefs and to recharge the aquifer...”

Community Quote from Long-Term Planning Recovery Survey

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NATURAL & CULTURAL RESOURCES

HOUSING

INFRASTRUCTURE

COMMUNITY PLANNING

ECONOMIC DEVELOPMENT

HEALTH & SOCIAL SERVICES

Stormwater Resilience and Flood Risk Management

participation

Consult

Complexity

High

Cost

High

Phase

Planning

Kuleana

County

State

County & State

Private

timing

1-2 years

6+ years

3-5 years

Estimated
completion

Lahaina Royal Complex Master Plan

The County of Maui Department of ʻŌiwi Resources is currently working with Group 70 International, Inc. (G70) to develop the Lahaina Royal Complex Master Plan. The project scope includes hydrology and water policy; wildfire resiliency and risk planning; biological and ecological assessment; cultural landscape architecture; community engagement protocol; transportation circulation planning; topographical survey; cultural and archaeological studies; soils and geotechnical studies; and boundary mapping.

View Presentation

December 2003 Final environmental Impact Statement, Lahaina Watershed Flood Control Project, Project Location Map.

“Incentivize 100% stormwater control and infiltration (with simple vegetative swales) to eliminate brown water events that impact our reefs and to recharge the aquifer...”

Community Quote from Long-Term Planning Recovery Survey

Purpose

This project will implement holistic stormwater and flood management, minimize stormwater runoff into the ocean and manage floodwaters across West Maui.

Project Description

Drainage Master Plan Update (to address localized flooding in urbanized areas of Lahaina) and preliminary design for the flood control project (retention basins and diversion channels mauka of Lahaina). This project is supported through U.S. Department of Agriculture (USDA) Natural Resources Conservation Service’s (NRCS) Watershed and Flood Prevention Operations Program. The County Department of Public Works (DPW) is the local sponsor with Stantec as contractor. The project is currently working on a supplementary environmental impact study since the original Environmental Impact Statement was written in the 1980s, and a hydrologic and hydraulic study. Once studies are completed, USDA NRCS and DPW will discuss the data, needs and how the Lahaina Watershed can address the needs through feasible conservation practices, either structural or non-structural.

Interdependencies and Roadblocks

This project aligns with the current effort to develop a watershed management plan for Kahoma and Kaua’ula watersheds. Currently there is a lack of sponsorship for NRCS projects. The current contract NRCS has is for roughly $1.4 million, but additional funds are needed. This project will have to compete nationally for design funding.

Contact

Project Details

Cost Estimate:

TBD

Existing Funding Sources:

Project Lead:

County of Maui Department of Public Works

Potential Funding Sources:

Watershed Protection Grants Program

Project Partners:

County Department of Agriculture
State Department of Health,
Surface Water Protection Branch
State Department of Land and Natural Resources, Division of Aquatics Resources
U.S. Army Corps of Engineers
U.S. Department of Agriculture, Natural Resources Conservation Service
U.S. Environmental Protection Agency

Alignment with West Maui Community Plan (WMCP)

Goal 2.1 Ready and resilient systems
Action 1.38 Update the Lahaina Town Drainage Master Plan for Low Impact Development (LID) and develop an implementation plan
Action 1.39 Support the implementation of flood control projects and siltation basins mauka of Honoapiʻilani Highway, including the remaining phases of the Lahaina Watershed project to address problem areas
Action 1.40 Maintain a current inventory of drainage facilities in West Maui for use in developing long-term plans to address stormwater issues
Action 1.41 Improve stormwater management systems along the Lower Honoapiʻilani Road to minimize stormwater runoff to the ocean

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Lahaina Bypass Phase 1C

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Short-Term (1-2 years)

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Stormwater Resilience and Flood Risk Management

Project Lead

Project Type

Plan Alignment

Funding Sources

Brief Description:

Milestones:

Project Location:

“Incentivize 100% stormwater control and infiltration (with simple vegetative swales) to eliminate brown water events that impact our reefs and to recharge the aquifer...”



BACK TO ALL PROJECTS

Stormwater Resilience and Flood Risk Management

1-2 years

6+ years

3-5 years

Lahaina Royal Complex Master Plan

“Incentivize 100% stormwater control and infiltration (with simple vegetative swales) to eliminate brown water events that impact our reefs and to recharge the aquifer...”

Purpose

Project Description

Interdependencies and Roadblocks

Contact

Project Details

Cost Estimate:

Existing Funding Sources:

Project Lead:

Potential Funding Sources:

Project Partners:

Alignment with West Maui Community Plan (WMCP)

Explore projects

Lahaina Bypass Phase 1C

Lahaina Royal Complex

Lahaina Harbor Restoration

Enhance Emergency Communication Networks

Ke Ola Hou

Kuhua Street Extension

Maui Emergency Management Agency (MEMA) Advancement Program

National Historic Landmark District Update

R-1 Recycled Water Expansion

West Maui Greenway

Rebuild the West Maui Senior Center

Wahikuli Subdivision Gravity Sewer System

Street Connectivity and Extensions

Watershed Planning for Revegetation & Reforestation of Lahaina & Kula

Water Source Development

Affordable Rental Housing Programs

Energy Resilience and Redundancy

Wildfire Risk Reduction and Mitigation

Agriculture Planning & Long Term Food Security

Asset Management and Acquisitions Program

Building Resilience Incentives

Creation of Lahaina Memorial

Community Facilities

Comprehensive Environmental Monitoring and Sampling Plan (CEMSP)

Economic Innovation and Development

Green Workforce Development

Healthcare Service Expansion

Homeowner Support Programs

Maui County Ferry

Lahaina Business Project

Lahaina Water Infrastructure Firefighting Capacity

Long-Term Disaster Case Management Program (DCMP)

Lahaina Water Infrastructure Resilience and Hardening

Preservation, Revitalization, and Reconstruction of Historic and Cultural Spaces

West Maui Business Center (WMBC)

West Maui Hospital