WHEN the tide went out, he got into his tractor and drove out over the soft sand and mud flats on the floor of the bay. A light northwesterly blew in off the Atlantic, and the smell of salt bristled in the air.

He had done his calculations. At each of the spots, he unloaded a large buoy. He secured them as best he could. He checked the map again, to ensure he was being fair and accurate.

Then Noel Carter returned home and got into his pick-up and followed the road around the shore, stopping here and there to hammer a post into the ground, bearing notice to the people of Strandhill that all was about to change for the idyllic village, and perhaps change utterly.

So began Carter's efforts a fortnight ago to inform the public about the implications of a proposed runway extension at Sligo airport. The proposal would bring a hulking mass of concrete protruding 270 metres out into a bay renowned as a special area of conservation. For Carter, the extension may well mean the end of his livelihood as a shellfish farmer. He felt obliged to act because of what he saw as a less than accurate portrayal of the plan by the authorities.

"They had an artist's impression of how far this was coming out past the shore and I could see immediately it was completely distorted, " he says.

Carter obtained the exact measurements and set out the actual boundaries for people to make up their own minds. He then put up the notices detailing the specific implications for the locality.

The airport company applied for planning permission for the extension on 28 December, during the Christmas holidays. The specifics as set out by an environmental impact study (EIS) weren't available until 11 January, the last day the applicant was required to furnish them. And now the people of Strandhill are waking up to the future.

"I have my specific arguments, but there is a whole range of arguments others have with this thing, " Carter says.

Strandhill hugs the Sligo coastline, in the shadow of the steep slopes of Knocknarea. The beach that fronts the village looks out on the relentless march of tall waves, but beneath the white horses, strong currents render the area treacherous for swimming.

Still, it has always attracted holidaymakers. Today, after rows and estates of new houses have been clipped on over the past decade, it looks more like a satellite village of Sligo town than a holiday destination.

It also serves as home for Sligo airport. Two flights a day to Dublin transport around 80 passengers in total, all of whom are heavily subsidised. Forty minutes up the road, Knock airport is also open for business. To continue operating commercial flights, Sligo must upgrade the runway to comply with new standards.

The end of the airport's runway tips the sheltered bay of Dorrins strand, where locals swim, and the Brent goose shelters from westerly storms, and Carter runs his shellfish farm.

Carter set up his business in 1988. To get to his home, he must cross the end of the existing runway, through which he has a right of way.

When a plane is taking off or landing, a red security truck is dispatched to block access.

Under the new proposal, high-grade security fencing will be installed, and he will have to call the terminal for permission to cross.

"We've never had a cross word, " he says. "But the new system would mean huge disruption for me."

Far more pressing are the implications for his livelihood.

After years of trial and error, he found the optimum spot to farm his fish in the deep channel that snakes into the bay.

When he hit upon it, his business took off. He now employs up to 15 people at the height of the season.

The new proposal will divert the channel from its natural route on the lowest sand bank to the highest, endangering his farming.

That is, of course, if nature responds as man directs it to with the artificial rerouting of the channel.

"Nobody knows where that channel will go if it is interfered with, " Carter says.

"They can't know. Any professional advice I've got says that it's impossible to give a definitive answer to that."

Yet the EIS states with certainty that the channel will turn sharply, thus accommodating Carter. There is no probability factor included.

Nature, the report implies, will do as nature is commanded to do.

The wrestle between development and preservation, particularly in the area of infrastructure, has been well played out through the boom years. But the proposed extension of Sligo airport raises questions about overkill and the spending of public money.

Each passenger into Sligo is subsided to the tune of Euro122 for a return trip to Dublin. If the state were to pay the taxi fare for a carload of business people visiting the town, it might be more economical, and would definitely go easier on the accursed carbon footprint.

The chairman of Sligo North West Airport Company is Albert Higgins, a Fianna Fáil county councillor, who holds the position as a trustee for the local authority, a majority shareholder.

He says everything will be considered during the planning process.

"All we've done is lodge the application, " he says. "It would be a big blow to Sligo if it was left without an air link."

He insists that the extension, the largest element of a Euro10m publicly-funded plan, is necessary, despite the proximity of Knock.

"Knock is Knock, Sligo is Sligo, " he says. "My argument is that we're carrying out two different functions. Knock is an international airport, Sligo is regional. We're a gateway city."

Last week, the local papers in Sligo were heralding the benefits to the county from the news that Knock would be operating transatlantic flights. One story pointed out that Knock is "only five miles from the Sligo border." When the planned bypass of Tubbercurry is complete, the Sligo-Knock road journey time will be reduced to around half an hour.

Strandhill native Helen McAuley learned how to swim in Dorrins strand, a pleasure she fears might now be lost to future generations.

"At a town development meeting this week, somebody described it as putting a Berlin Wall into the bay, " she says. "Apart from the swimming, which is very safe, tourism will be affected, like the pony treks that go out to Coney island from there. It was only when I got the environmental statement this week that I realised the extent of it."

Fellow townie Kieran Foley's main concern is for the wildlife.

"I've great respect for the people involved in the airport, but the visual impact and the impact on wildlife there would be huge, " he says.

"Positive progress would be a proper road infrastructure.

Knock airport is a very good facility and an ideal location for Sligo."

Birdwatch Ireland, Coastwatch and An Taisce have all expressed serious reservations about the proposal.

According to Higgins, if the planning process goes smoothly, the new runway could be functional by the middle of next year. If the plan is thwarted, then he reckons many of the 40 jobs at the airport will be in jeopardy.

Serious division over the plan is inevitable in the coming months. With little direct benefit for Strandhill itself, feelings in the village are already running high. And before the fat lady sings, opinions may stiffen and pull with the ferocity of the currents lurking beneath the breakers offshore.