This article was originally published at Honolulu Star-Advertiser and is republished by permission.

On June 20, the Hawai‘i Supreme Court ruled in the Hui o Na Wai ‘Eha suit over water diversions from Central Maui’s “Four Great Waters” (Waihee, Waiehu, Wailuku and Waikapu streams), that Hawai‘i public agencies must act to protect public and Native Hawaiian rights to common resources. How does this affect other water decisions?

The court overturned a 2021 state Water Commission decision for failing to take the initiative to return more flows to the streams after the Hawaiian Commercial and Sugar Co. plantation closed in 2016. As the ruling makes clear, Hawai‘i’s Constitution establishes a powerful public trust duty to protect water resources and Native Hawaiian water rights. This duty is affirmative — it compels action.

At the same time, the court upheld the commission’s authority to hold large diverters accountable. Here, for the first time, the commission imposed some restraints on water use permits, declining to sacrifice streams for growing golf course turf or subsidizing corporate farming.

This decision sends a strong message for other upcoming cases. Last year’s Maui wildfires exposed the impacts and injustices of more than a century of private water diversions. In West Maui, the decision speaks loud and clear: The commission’s duty is to restore Lahaina waters, not to reserve it for luxury landscaping and swimming pools.

You were part of the Earthjustice team working with Our Children’s Trust on the Navahine v. Hawai‘i Department of Transportation suit claiming youths’ constitutional right to a “clean and healthful environment.” What’s its significance?

Here’s an example of the state boldly owning its trust obligations to protect our environment. For the first time, a government joined with its youth citizens in a binding court agreement to take action in meeting the climate emergency. In this case, the state Department of Transportation rose to the historic moment, committing to establish a comprehensive program for decarbonizing the statewide transportation system. This case is a model for the nation and world in tackling transportation emissions at the systems level.

The agreement recognizes the unique legal obligation the state and court have to our youth. This principle of intergenerational justice is at the heart of Hawai‘i’s public trust law.

Earthjustice pressed what it called “The Clean Water Case of the Century,” County of Maui v. Hawai‘i Wildlife Fund, all the way to the U.S. Supreme Court, and prevailed in 2021. The court held that pollution from the Lahaina wastewater treatment plant that flowed into the ocean violates the Clean Water Act, even if discharged into the ground before reaching protected waters. What happens next?

Maui County is now seeking a Clean Water Act permit, which will limit the Lahaina sewage plant’s discharges into the ocean. Under a court-ordered settlement, the county is also building projects to reuse treated wastewater. This supports the water supply in arid West Maui and reduces pressure to divert streams, while also avoiding the pollution of nearshore reefs. It’s the win-win solution the community has been envisioning for decades.

In a separate lawsuit, Hawai‘i County recently admitted that the Lahaina case requires it to address discharges from its Kealakehe sewage plant that pollute Honokohau Harbor. The state Department of Health is also developing a strategy to address many sources of pollution statewide that contaminate our ocean and streams via groundwater.

What is the status of commercial aquarium fishing in West Hawai‘i?

We went to court in 2012 because the aquarium industry was stripping our reefs of fish, and in 2017 the Hawai‘i Supreme Court ruled that the state must examine impacts on local ecosystems and communities. Fish collection was supposed to be halted, but a loophole was created to sidestep the injunction, which we took back to court to stop in 2021.

Meanwhile, the industry has insisted that snatching hundreds of thousands of fish each year for the global pet industry is just fine. The state Land Board rejected the industry’s first environmental impact statement, then the industry turned around with another that doubled down on the same defects. The board rubberstamped it, and we’ve taken it to the Hawai‘i Supreme Court again, with a decision pending.

In December 2023, the board approved a public request to issue new regulations banning commercial collection. But the industry is working with agency staff to stonewall and reopen aquarium collection instead. The industry is pushing to take us backward, even while climate-change stresses mount.

What are the implications of Hawai‘i Supreme Court decisions on the state’s responsibility to advance the public trust?

The public trust is a founding legal principle, enshrined in Hawai‘i’s Constitution and rooted in Native Hawaiian custom, that the state holds natural resources in trust for present and future generations. This goes far beyond the power to regulate and envisions a broader paradigm of public rights and government responsibilities. The Hawai‘i Supreme Court has been at the forefront of developing this law in the modern age, beginning half a century ago when it told plantations that water wasn’t their property, but rather a common resource and legacy for all.

This concept only resonates more urgently today in this era of climate crisis. In its latest decision, the court insisted that the public trust holds the state to higher standards of “openness, diligence, and foresight” when “vital public trust resources” are at stake. The public trust is a living law that will evolve to meet new needs, including humanity’s right to a livable climate.