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Improving Water Quality in the Ala Wai Watershed

This webpage is a resource for community members, planners, and policy makers to learn about water quality issues the Ala Wai Watershed. The University of Hawai’i Sea Grant College Program is kicking off work in 2024 to actively improve the health of the Ala Wai Canal though community outreach and in-ground green infrastructure pilot projects.

This project is funded by a grant/cooperative agreement from the National Oceanic and Atmospheric Administration (NOAA), Project A/AS-56 which is sponsored by the University of Hawai’i Sea Grant College Program, School of Ocean and Earth Science and Technology (SOEST), under Institutional Grant No. NA23OAR4690519 from NOAA Office of Sea Grant, Department of Commerce. The views expressed herein are those of the author(s) and do not necessarily reflect the views of NOAA or any of its subagencies. UNIHI-SEAGRANT-4859.

Explore the sections below to learn more about our current efforts.

Ala Wai Watershed Map

There are issues within the Ala Wai Watershed with both excessive water quantity (flooding) and quality (pollution). This project is focused on addressing water quality issues in the Ala Wai Canal, a man-made waterway in the lower portion of the watershed. Water quality is degraded when pollutants like sediment, chemicals, or harmful microorganisms contaminate a body of water.

Green stormwater infrastructure, also known as nature-based solutions, include solutions like bioswales and urban wetlands. Green stormwater infrastructure is powered by natural processes to slow flow, filter, and purify water. In addition to providing ecosystem and human health benefits, these systems can improve urban aesthetics and appeal.

In this project, Hawaiʻi Sea Grant is working to:

  • Identify hotspots, policies, and practices that contribute to pollution in the Ala Wai watershed
  • Collect of robust community feedback on observations and preferred mitigation options
  • Invest in demonstration projects through the allocation of mini grants
  • Create future management recommendations
  • Develop and foster community practices for improved watershed resilience

The Ala Wai Watershed includes the Pālolo, Mānoa and Makīkī valleys and is home to 200,000 residents and 80,000 visitors on any given day. The watershed includes many cultural sites, initiatives, stories, and moʻolelo of place that hold extraordinary cultural value and significance. It is also home to the economic hubs of Waikīkī, UH Mānoa, and Mōʻiliʻili.

The watershed includes rich and diverse natural resources, such as forest, riparian, coastal and marine ecosystems, and public spaces, parks, and waterbodies that are heavily used for recreation by the community.

Ala Wai Watershed for survey

Water moves from land to sea, mauka to makai. Water quality conditions in the coastal lowlands of the watershed have degraded as a result of upstream urbanization (the conversion of green space to impervious land area), individual and collective management choices, ecosystem loss, and waterway channelization. The Ala Wai Watershed drains into the Ala Wai Canal, which is chronically polluted.

Natural resources face pressures from urban development, invasive species, polluted stormwater, and runoff. The Ala Wai Canal in particular suffers from severe pollution, including sedimentation, bacteria, and heavy metals, organic debris, and trash that are generated on both private and public properties throughout the watershed.

Brown water event in the Ala Wai Canal

The Hawai’i Sea Grant College Program designed a survey to learn more about the community’s perceptions of water quality within the Ala Wai Watershed. Results will help to inform a process for implementing demonstration projects to address water quality in the Ala Wai Canal and throughout the watershed.

You do not need to reside in the Ala Wai watershed to take this survey, which should take about 5-10 minutes to complete. Mahalo for your participation!

Click here to take the survey–**update link

Hawai’i Sea Grant recognizes that communities hold the knowledge and understanding of their places. In order to support nature-based solutions to the watershed’s biggest challenges, Hawai’i Sea Grant is distributing competitive mini-grants to organizations who are interested in installing, maintaining, and educating the public about a nature-based solution/green-infrastructure project within the watershed. 

Coming late spring 2024!

To get more information when it becomes available, please email &

There are many organizations working within the watershed to improve water quality and quantity and other conservation efforts. Check out an interactive map created by Hawaii Green Growth of relevant organizations and projects below:

Below is a list of reports, studies, and articles written on the watershed without affiliation with Hawai’i Sea Grant.

Pre-1900: Waikīkī is a vast marshland of about 2,000 acres. Expanses of wetland agriculture dominate the watershed, including the modern neighborhoods of Waikīkī, Maikiki, Mōʻiliʻili, and Mānoa.

Waikiki pre-Ala Wai Canal

Extensive wetland agriculture in marshlands. (Image: Bishop Museum Archives)


1901: The first hotel in Waikīkī, the Moana Hotel, opens 

Waikiki's Moana Hotel

The Moana Hotel in 1920, 1 year prior to the Ala Wai Canal’s construction (Image: Bishop Museum Archives)

1921: Board of Health President Lucius Pinkham orders the construction of the Ala Wai Canal, which effectively drained Waikīkī of its wetlands which were host to loʻi kalo, loko ʻia, duck ponds, rice ponds, and their stewards

1928: Construction of the Ala Wai Canal is finished. The original plan was to have two outlets into the ocean, but only the west outlet is included

Original plan for the Ala Wai Canal included a second outlet to the ocean (Image: Star Advertiser)

1962: Flood Control Act of 1962 authorized and directed the U.S. Army to do surveys in Hawaiʻi with the goal of flood control 

1965: Ala Wai Canal reaches capacity, flooding Waikīkī and causing streams in Mānoa and Pālolo Valleys to record the highest peaks since 1921

Ala Wai Boulevard with flooded water from the Ala Wai Canal in 1965 (Image: Images of Old Hawaiʻi)

1967: Ala Wai Canal reaches capacity, flooding Waikīkī for the second time

1967 + 1978: The Ala Wai Canal is dredged 

Ala Wai Canal in 1967

The canal in 1967. (Image: Honolulu Star-Bulletin)

1992: Hurricane Iniki hits Hawaiʻi, mainly affecting the island of Kauaʻi

Image of wave crashing in Waikīkī area during Hurricane Iniki (Image: CNN)

1999: The Ala Wai Flood Risk Management (FRM) project with the United States Army Corps of Engineers begins 

2002: The Ala Wai Canal is dredged for a third time 

Other resources: 

2004: Mānoa Stream floods

The aftermath of Mānoa Stream flooding at the Woodlawn Bridge in 2004 (Image: National Weather Service)

2006: Mākiki Stream floods

2013: Mākiki Stream is dredged

2014: Aloha+ Challenge (Hawaiʻiʻs locally and culturally appropriate framework for the United Nations Sustainable Development Goals) launched

2015: Department of Land and Natural Resources releases reports on options for improving water quality within the Ala Wai Canal 

2017: Act 125 requiring the replacement of all cesspools by 2050 is passed

2017: Notable king tide event in Waikīkī

Water crashes against concrete walkway near Fort DeRussy in Waikīkī in 2017 (Image: Civil Beat)

2018: Funding for Ala Wai Flood Risk Management project is approved

2019: 100 year anniversary of building of the Ala Wai Canal 

Students reflecting on Sean Connelly’s Ala Wai Centennial piece in 2019 (Image: Ala Wai Centennial )

2020: U.S. Army Corps of Engineers release  Engineering Documentation Report for the Ala Wai Flood Risk Management project

2023: U.S. Army Corps of Engineers indicate plan to release second version of the plan for the Ala Wai Flood Risk Management project

2023: Congressional Funds are allocated to this project for improving water quality within the Ala Wai Watershed

USGS “Ground Water in Hawaii” – USGS, 2016

Biological and water and sediment quality surveys in Mānoa Stream, Honolulu, Hawaiʻi – AECOS, Inc., 2016

Mānoa Disaster Preparedness Plan – Be Ready Mānoa, 2017

Storm Water BMP Guide for New and Redevelopment – City and County of Honolulu, Department of Planning and Permitting, 2017

Strategic Plan for the Control and Management of Albizia in Hawaiʻi – Hawaiʻi Invasive Species Council, 2018

Trash Reduction Plan – Hawaiʻi State Department of Transportation – Protect our Water, 2019

2019 Oʻahu Resilience Strategy – Office of Climate Change, Sustainability, and Resiliency, 2019

Green Infrastructure the Solution for Hawaii’s Stormwater Problem (Out & About) – Think Tech Hawaiʻi, 2019

Wai in Waikīkī: Past, Present & Future Paths Forward for the Ala Wai Watershed – Emily Nālani Medeiros and Sarah Michal Hamid, 2020

Water Is Wealth – Places Journal, Sara Jensen Carr, 2021

Storm Water Management Plan – Department of Facility Maintenance, 2021

Characterizing Competing Viewpoints in Stormwater Governance: An Urban Honolulu Case Study – Aida D. Arik, 2021

Transforming the Ala Wai – Sea Grant Hawaiʻi, 2022

The Battle to Save Waikiki Beach – Melanie Warner, Politico Magazine, 2022

Storm Water Utility Oʻahu: Neighborhood Board Update – Stormwater Utility Oʻahu, 2022

Cherish Protect Restore Campaign – Mālama Maunalua, 2022

Resources– Ala Wai Watershed Collaboration

Ala Wai Watershed Restoration– Oceanit

Fresh Water Security for Hawaiʻi – Hawaiʻi Community Foundation

Genki Ala Wai Project – Genki Ala Wai Project

Ala Wai Watershed Project – ʻIolani School

Water Quality in the Ala Wai Canal – SMART Ala Wai

Ala Pono: An Ala Wai Crossing – Department of Transportation Services: Complete Streets Program

Green Infrastructure Practices for Hawaiʻi – Hawaiʻi Sea Grant

Hawaiian Stream Animals – ʻIolani School

Hawaiʻiʻs Water Cycle – Board of Water Supply

Hawaiʻi Watersheds and Forests Storymap – Department of Land and Natural Resources

For more information, please email & or call (808) 956-3012.

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