Māʻalaea Bay is a community resource — a place where people surf, fish, swim, paddle, whalewatch and embark on ocean adventures. Unfortunately, the water quality in Mā‘alaea Bay is compromised by storm water and sediment run-off, as well as other pollution originating from land. This nearshore ocean pollution adversely impacts areas in Māʻalaea Bay that are important for recreation, and also undermines the health of coral reefs and sea turtle feeding areas just outside the harbor. Studies have shown that sedimentation originating in Māʻalaea Bay drifts towards the coral reefs of Olowalu.
Our two-part “Vision for Pohakea”
Pohakea is the name of the 4,000+ acre watershed upslope from Māʻalaea Bay. Pohakea watershed has several gulches that all discharge into Māʻalaea Bay and the harbor.
Maui Nui Marine Resource Council (MNMRC) developed a plan called “Vision for Pohakea,” to reduce sediment and pollutants in Māʻalaea Bay and Māʻalaea Harbor.
Part 1: Using oysters to improve water quality
The first part of the “Vision for Pohakea” was a test project to use caged, nonreproductive oysters to help improve ocean water quality at the harbor.
Oysters are nature’s most efficient water filters; they eat by pumping large volumes of water through their bodies. In the process, they capture sediment and pollutants from the water column. Estimates are that a single oyster can filter up to 50 gallons of ocean water per day depending on conditions. In doing this they help to improve water clarity and quality allowing corals and other marine animals to receive the sunlight they need to thrive.
After two years of testing oysters in Māʻalaea Harbor, it became clear that they did not thrive as well as originally hoped. They struggled to find food in certain seasons of the year and ultimately did not sustain a large enough population to significantly improve the water quality. The pilot project came to a close in May 2024.
The oyster pilot project in Māʻalaea was generously supported by the County of Maui Mayor’s Office of Economic Development. Additional support is provided by Hawaiʻi Tourism through the Aloha ʻĀina Program.
Part 2: Working upslope in Pohakea watershed
As part of our work to improve ocean water quality in this nearshore area, Maui Nui Marine Resource Council is also working in Pohakea watershed to prevent sediment-laden runoff, debris and pollutants from entering the bay and harbor.
We’ve commissioned and paid for a detailed stormwater management plan by local environmental management experts Maui Environmental Consulting to help us understand the problems and challenges in Pohakea watershed, and to identify projects on land that we can implement in the near future. We are now implementing projects outlined in the plan, thanks to support from National Fish and Wildlife Foundation and the County of Maui Mayor’s Office of Economic Development.
To download the Pohakea Stormwater Management Plan, please click here.
To gather baseline data about current ocean water quality in Māʻalaea Bay, Maui Nui Marine Resource Council is conducting regular kayak-based ocean water monitoring throughout the bay, using an electronic monitoring probe that provides a stream of data in real-time as the kayak travels through the water. The probe was purchased as the result of a grant from Lush Cosmetics Charity Pot.
Funding for our work in Pohakea is provided by:
National Fish and Wildlife Foundation
Hawaiʻi Tourism through the Aloha ʻĀina program
County of Maui Mayor’s Office of Economic Development
Please note: The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Government or the National Fish and Wildlife Foundation and its funding sources. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Government, or the National Fish and Wildlife Foundation or its funding sources.
