9/26/25 – Working Together to Protect Hawaiʻi’s Estuaries

Working Together to Protect Hawaiʻi's Estuaries

As National Estuaries Week 2025 winds down, we wanted to highlight the vital role estuaries, or muliwai, play in Hawaiʻi's natural environment and cultural heritage. These unique habitats-where a brackish mix of freshwater and saltwater combine-house a variety of marine organisms that positively impact nearshore ecosystems and communities statewide.

Estuaries are referred to by many names including bays, harbors, inlets, and lagoons. Examples of Hawaiian estuaries include Maunalua Bay on Oʻahu, Keālia Ponds on Maui, Anahola River on Kauaʻi, and Kīholo Bay on Hawaiʻi Island.

They are among the most productive ecosystems on Earth and provide important benefits for communities and wildlife alike. Staff at DLNR's Division of Aquatic Resources (DAR) work with other agencies and local communities to restore and preserve these valuable areas across the state.

Estuaries are often called "nurseries of the sea" because they support fish, shellfish, limu (seaweed), and waterbirds. Their shallow, nutrient-rich waters offer shelter and food for a wide variety of species, making them essential for healthy marine and freshwater habitats.

Beyond supporting wildlife, estuaries help protect our environment and communities. They naturally filter out sediment and pollutants, improving water quality and helping to protect coral reefs. Wetlands, marshes, and seagrass beds also reduce the risk of flooding and coastal erosion by acting as natural barriers.

Healthy estuaries support local economies and provide spaces for people to enjoy recreational activities like fishing, hunting, foraging and bird watching. Estuaries are integral to the traditional food system in Hawai'i, providing a resilient food supply to Native Hawaiian communities. The steady flow of residents and visitors to these coastal areas highlights their ongoing value.

"These environments are irreplaceable and vital to the health of the islands," said Dr. Kim Peyton, research scientist at DAR. "The importance of estuaries boils down to this: their health directly impacts our economy, food security, and ability to withstand climate change."

As we mark National Estuaries Week 2025, we recognize efforts being made by DAR staff, local organizations and community members to ensure our estuaries continue to thrive for generations to come.