Hawaii County Launches Online Atlas to Help Residents Navigate Coastal Hazards

What a homeowner in Kailua-Kona "thinks they know" about their shoreline and what Hawaii County's planners actually have on file are increasingly two different things. A new interactive Coastal Zone Viewer, now live through the Hawaii County Planning Department, makes that gap visible for the first time in a single publicly accessible map — and for anyone with property, a business, or a building project near the water, the implications run well beyond curiosity.

The viewer, accessible at planning.hawaiicounty.gov, layers coastal hazard data, ecosystem classifications, Special Management Area boundaries, and shoreline policy requirements onto a searchable map of the entire island. It replaces a process that previously required residents to cross-reference multiple state and county documents before understanding whether a renovation, a seawall repair, or a new structure would trigger SMA review.

Planning Director Jeff Darrow, who has guided the department's coastal zone management work through more than two decades of service, has positioned the tool as central to the county's effort to bring planning decisions into the climate era. The Big Island's coastline faces a documented combination of threats that no other Hawaii county deals with in quite the same concentration: erosion, sea level rise, tsunamis, storm flooding, earthquakes, subsidence, and active lava flows.

That last pairing — subsidence alongside lava — is where many Big Island property owners encounter their first surprise. Communities in North Kona, stretching from the resort corridor near Kekaha Kai State Park down through the Four Seasons and Hualalai coast, sit atop relatively young lava flows that are geologically active and subject to subsidence even as new volcanic material continues to add land elsewhere on the island. The stable-looking lava bench fronting a vacation rental or a shoreline restaurant may carry a hazard classification that affects insurance eligibility and rebuild rights in ways the owner has never had reason to check.

In South Kohala, the stretch between Kawaihae Harbor and Hapuna Beach encompasses both high-use recreation areas and sensitive marine ecosystems. The viewer's ecosystem layer can reveal coral reef or anchialine pool designations adjacent to parcels that owners may have assumed were straightforward development candidates, adding an entirely separate layer of SMA scrutiny before a single permit application is filed.

For Hilo's bayfront, where tsunami inundation history is well understood but chronic king-tide flooding is accelerating, the viewer allows a parcel-level look at combined exposure that aggregate hazard maps have never offered before.

Using the tool for a real permitting question follows a direct path: enter a Tax Map Key number or address, activate the SMA boundary layer to confirm whether a property falls within the Special Management Area, then toggle the hazard and ecosystem overlays to identify which specific conditions govern what can be built, rebuilt after storm damage, or expanded toward the shoreline. Properties inside the SMA face permit requirements that go well beyond standard zoning, and the erosion risk layer can determine whether a coastal setback calculation pushes a proposed structure further inland than an owner or contractor anticipated.

The county's Planning Department has noted that climate-driven changes along the Big Island's 266 miles of coastline are outpacing the static documents that residents and contractors have relied on for years. The Coastal Zone Viewer is designed to close that gap before a permit gets denied, a lender flags an uninsurable hazard, or a business discovers its ocean-facing expansion sits squarely inside an ecosystem protection zone that no one flagged at closing.