Niihau, also known as the Forbidden Island, is home to about 130 Hawaiian residents whose generational ties to the smallest inhabited Hawaiian Island run deep.

It’s also populated by free-range herds of cattle, sheep and exotic eland antelope native to Africa, all of which have historically earned the publicly restricted island of 70 square miles a property tax abatement for agriculture.

But last year when the Robinson family — Niihau’s private landowners — applied to renew the island’s 20-year agricultural dedication, their property taxes jumped by about $100,000, quadrupling from $32,000 in 2020 to about $130,000 in 2021 and 2022.

That’s because Kauai County for the first time carved out portions of the island being used for residential, industrial and commercial purposes rather than agriculture and removed that acreage from what was formerly an island-wide agricultural designation, according to Kauai County Finance Director Reiko Matsuyama. The county also updated the soil rates on the dedicated acreage, which further skyrocketed Niihau’s assessed value.

On Wednesday the Kauai County Council approved legislation to impose an annual flat tax rate of $40,000 for Niihau based on a series of factors, including the island’s contributions to agriculture and Hawaiian culture and its sparse use of county services.

“This really holds the Robinsons accountable for keeping the island in agriculture and continuing to provide Native Hawaiian families with housing and the lifestyle they have been accustomed to for generations,” said Councilman Bill DeCosta, who co-sponsored the bill with Councilman Luke Evslin.

“There are so many billionaires that are here in Hawaii that want a piece of this heaven,” DeCosta added. “Niihau is one area that we felt as politicians we could assist the landowners with the tax revenue that they would have to pay based on what they do for the community, the Native Hawaiian people of Niihau and what services we as a county don’t provide.”

Bruce Robinson, one of the landowners, declined to comment for this story through DeCosta.

One factor considered by the council is that the county does not provide the island with road maintenance, trash collection or police and fire protection.

The Kauai Fire Department and Kauai Police Department do not even have response protocols for Niihau, according to Evslin. KFD cannot access the island with its helicopter, he said, and KPD would need the landowner’s permission to investigate crime there since it’s a private island.

During the Covid-19 pandemic, however, the county’s incident management team was in regular contact with the Robinsons, according to Kauai Emergency Management Agency Administrator Elton Ushio. The Hawaii Health Department’s Kauai District Health Office took the lead to deploy teams to Niihau on several occasions in response to coronavirus disease outbreaks, providing testing and vaccinations, Ushio said.

Another consideration was that the Robinsons provide housing to about 40 Hawaiian families who continue to reside on Niihau.

The council has the discretion to amend or abolish the tax “upon any significant change of use” if, for example, there is a change in Niihau’s ownership or a hotel resort is developed on the island.

“In my mind it’s not a perfect solution,” Evslin said. “It’s a little bit nebulous in that we’re saying that because of all these factors, this is what we’re going to do because this is a unique situation. But we can change it for any reason we want at any time. Even if there’s no change in use, the council can still change it.”

With no paved roads, cars, stores, restaurants, doctors or indoor plumbing, Niihau has been owned by a single family for more than 150 years. Landowners Bruce and Keith Robinson continue to uphold a pledge forged in 1864 when King Kamehameha V sold the island to the Sinclair family for $10,000 on the condition that they preserve the Hawaiian language and Niihau’s unique culture and lifestyle.

The island’s population has declined in recent decades in step with a shortage of jobs, according to the Niihau Cultural Heritage Foundation. Some residents make a living weaving prized Niihau shells into lei. Otherwise, part-time work is available for only a small number of residents at the island’s school, helicopter tour company Niihau Safaris and at a small U.S. Navy installation.

Jobs, as well as the island’s agricultural heritage, are challenged by a lack of water. Niihau Ranch long provided ample work for residents until its closure in 1999 due to the difficult economics associated with raising livestock on an arid island.

Niihau is home to Lake Halalii, the largest lake in Hawaii, but it is dependent on rainfall and disappears during periods of drought.

Livestock freerange on the island due to the limited availability of water, according to DeCosta. The lack of traditional fenced-in grazing area makes it difficult for the county to quantify how much acreage is utilized for agriculture, he said.

DeCosta also noted some of the Robinson’s philanthropic contributions to Kauai. In the aftermath of the historic 2018 flood that devastated Kauai’s north shore, the Robinsons volunteered to bring excavators and other heavy machinery on a barge to the north shore to help clear mud-clogged roadways, he said.

The Robinsons’ private ownership of Niihau can be compared to billionaire tech entrepreneur Larry Ellison’s 98% ownership stake in the island of Lanai, including a third of the housing, the water utility and twin luxury resorts. Unlike Niihau, Lanai is a publicly accessible part of Maui County.

Ellison purchased Lanai in 2012 for a reported $300 million.