Some of the best and most productive farmland left on O'ahu will soon be history if we give David Murdock, owner of Castle & Cooke, permission to build 5,000 houses on Koa Ridge. Together with projects already approved in Central O'ahu — Waiawa by Gentry, Royal Kunia — it's a repeat of a failed 20th-century policy: urban sprawl.

Ours would hardly be the first civilization to destroy its best farmland en route to ecological suicide, not even the first American one. The Mayans built stone cities, pyramids and reservoirs long before a human set foot on Hawai'i. Then their rains failed ... for 200 years.

In Hawai'i we've reached a historic marker. We've seen the future. The last oil spike underlined our dangerous dependence on imported food and energy. Oil prices are rising again. Droughts presage changing rain patterns. Now we know: All new development must promote sustainability and self-sufficiency.

Yet, as Murdock's experts admit, Koa Ridge represents 5 percent of O'ahu's remaining prime irrigable farmland. This land has been successfully and profitably growing food for decades. If we pave it over, it will be lost forever.

In the past 20 years we've wantonly developed nearly 3,300 acres of prime farmland. As each parcel disappeared, the price of the remaining land went up, making life ever more difficult for farmers.

So what we decide to do with Koa Ridge, this huge piece of our 'āina, will be a loud signal of how we want O'ahu to evolve — our vision of the future of our cities and countryside. Do we mean it when we say "let the country be country?" Do we mean it when we speechify about self-sufficiency? Because this massive project threatens our long-term goal to feed ourselves and sustain future generations.

From the governor on down, everyone agrees we should become less reliant on cars, more reliant on locally grown food and energy. We voted to build a mass-transit system to take cars off the road and focus growth around a dense urban core. As private investors, homeowners, and as a community we're pouring billions into biofuel power plants, undersea electric cables, photovoltaics, wind farms, electric car charging stations, algae-to-energy research and a slew of other projects to promote a sustainable future.

Meanwhile O'ahu's agriculture revolution is just beginning. It takes time to recover from the death of plantation monoculture, yet already the acreage devoted to vegetables increased 475 percent between 1990 and 2004.

Led by top restaurants, hotels and Whole Foods, by educational campaigns to encourage keiki to eat more veggies, and by oil-driven food price inflation, the demand for locally grown produce is set to explode. We'll soon need every acre of farmland available.

In the face of this progress and those realities, Koa Ridge is a monstrous throwback. It's a good old-fashioned gas-guzzling, freeway-clogging, water-slurping, stream-polluting, farmland-destroying urban sprawl that will eat up the last green corridor between Pearl City and Mililani.

This proposed new bedroom community is nowhere near the urban core of Honolulu or the Second City of Kapolei. It's nowhere near the train. Its 15,000 occupants will flood onto H2 and H1, turning what is already the nation's second worst commute into an even worse nightmare of gridlock — boosting oil consumption and carbon dioxide pollution, cutting productivity and robbing families of precious time together.

The state Land Use Commission is not obliged to accept the petition by Murdock — one of the 200 richest people on the planet — to reclassify prime farmland so he can build 5,000 houses and vast commercial properties. Article XI of the constitution enjoins the state to "conserve and protect agricultural lands (and) increase self-sufficiency."

Our statutes instruct the Land Use Commission to "assure the availability of agricultural suitable lands with adequate water to accommodate present and future needs."

With its rampant disregard for those concerns, this rotten Koa Ridge idea has passed its sell-by date. Please ask the Land Use Commission to deny Murdock's petition to create more urban sprawl.

Anthony Aalto and Robert D. Harris represent the Sierra Club, Hawai'i Chapter. They wrote this commentary for The Advertiser.