Why It Matters
A series of damaging storms that struck Hawaii last month has renewed scrutiny of the state’s approach to managing water — and whether decades of paving over natural landscapes has left communities far more vulnerable than they need to be. For Hawaii, the question of flood resilience is increasingly tied to land use, tree cover, and the restoration of traditional water-management practices.
What Happened
Kona low storms rolled through the Hawaiian Islands last month, triggering evacuations and widespread flooding across Oʻahu and Maui County. Communities affected included Haleʻiwa, Waialua, Lahaina, Kīhei, ʻĪao Valley, and East Molokaʻi — areas spanning two islands and a range of landscapes from coastal lowlands to valley corridors.
The flooding struck with particular force near temporary housing set up for survivors of the 2023 Lahaina wildfire, compounding the hardship for residents still working to recover from that disaster. Drainage and sewer systems overflowed in multiple locations, carrying sediment, debris, and pollutants into nearshore coastal waters.
Infrastructure experts and land planners have pointed to a structural problem underlying the damage: much of Hawaii’s built environment is designed to shed water as quickly as possible — off roofs, across roads, and into drainage channels — rather than slow it down, absorb it, or allow it to replenish groundwater supplies.
The Case for Trees as Infrastructure
The traditional Hawaiian land division system known as the ahupuaʻa organized communities along watershed lines, running from the mountains to the sea. Forested uplands and carefully maintained vegetation zones worked together to regulate water flow, reduce erosion, and sustain stream systems. That approach has largely been displaced by impermeable surfaces and engineered drainage.
Trees and healthy soils perform a range of hydrological functions that hard infrastructure cannot replicate: they intercept rainfall before it hits the ground, increase the rate at which water infiltrates the soil, stabilize hillside slopes against erosion, reduce surface runoff that overwhelms drainage systems, and gradually recharge underground aquifers. Restoring that vegetative cover — particularly in flood-prone areas — is being discussed as a practical complement to conventional flood-control investment.
Not all trees are equal in this equation. Albizia, a fast-growing invasive species widespread across the Hawaiian Islands, has been identified as a problem tree. It is prone to structural failure during heavy rain and wind events, making it a hazard rather than an asset in storm conditions. Removal of albizia and replacement with native or appropriate species is seen as one component of a broader revegetation strategy.
By the Numbers
- 2 islands — Oʻahu and Maui County — experienced evacuations and flood warnings during last month’s storms
- 6 communities specifically identified as affected: Haleʻiwa, Waialua, Lahaina, Kīhei, ʻĪao Valley, and East Molokaʻi
- Multiple recovery corridors identified for prioritized revegetation, including the North Shore, Wahiawā, Kīhei, Kula, Lahaina, West Maui, and ʻĪao Valley
- Several land categories flagged for urgent action: fire-impacted areas in Kula, mid-elevation ranch lands, and wildfire-scarred sections of Lahaina and West Maui
Zoom Out
Hawaii’s situation reflects a challenge facing communities across the United States: infrastructure built for a different climate and a different relationship with the natural landscape is struggling to cope with intensifying storm events. States from Louisiana to California have begun incorporating “green infrastructure” — vegetation, wetlands, and permeable surfaces — into flood-management strategies alongside traditional engineered systems.
For Hawaii, the challenge is amplified by the legacy of wildfire damage on Maui, where stripped hillsides and destabilized soils heighten flood and landslide risk. The overlap of fire recovery and flood vulnerability in places like Lahaina and Kula makes revegetation both an environmental and a public safety priority. Hawaii’s broader land-use and legal landscape continues to generate significant debate, as seen in recent legal challenges involving homestead policies and campaign finance regulations that place additional pressures on state governance.
What’s Next
Recovery efforts in flood-affected communities are ongoing. Planners and environmental advocates are pressing for investment in watershed restoration alongside standard drainage repairs, particularly in corridors identified as repeatedly flood-prone. The question of how aggressively Hawaii moves to restore tree cover and natural hydrology — and how that work is funded and coordinated — is expected to remain a central issue as the state weighs its long-term infrastructure priorities ahead of the August primary elections, where infrastructure and disaster preparedness may figure into candidate platforms.