The shoreside hotel was bought in 1999 by Paddy Crerar of Oban, and a new pool was part of a plan to create a destination hotel which included the addition of 80 new hotel rooms, a waterfront bar lounge and a 130-cover restaurant, all of which was completed in 2003.
But with Crerar Hotels now upgrading those facilities, Inveraray residents fear they may be excluded from using the pool without first taking out an expensive spa package.
Amid a flurry of locals expressing their frustration over the past week on social media has been Anne MacPherson, an empoyee at the hotel in 1999 and one of the first leisure members - with a membership number of 007.
Mrs MacPherson told the Argyllshire Advertiser: 'The Loch Fyne Hotel has barred local people from using its pool without using expensive spa treatments first.
'I worked there in 1999 when it opened and the reason they got planning permission from Argyll and Bute Council was on the proviso they allowed locals and others to access the pool. I don’t think they have the right to do this.'
'You could pay at the desk and also get a monthly membership for £30 or, as I did, a family yearly one for £750, including use of the hot tub and sauna steam room,' Mrs MacPherson continued.
Crerar Hotels said that there were no planning stipulations regarding who might use the facilities.
A spokesperson for the company added: 'Following a six-figure refurbishment, our brand-new Shore Spa is scheduled to open at the end of March.
'It will offer additional therapy suites and a renovated pool with heated beds and swan-neck pool fountains, as well as thermal experiences including a healing Himalayan salt room, eucalyptus steam treatment and sauna alongside a brand-new terrace with loch-side saunas and ice drenches, plus further improvements to the existing hydro experience.
'Shore Spa, including the pool, will be open to all, locals and residents alike.
'Day passes, as well as annual spa memberships for access to the pool and thermal experiences for over-16s, will be available and we'll be announcing details - including costs - in due course.
'We are, of course, offering a very different service to that of the excellent community pool in nearby Lochgilphead or the superb facilities at Atlantis in Oban, and our pricing will reflect that.'
The company said the hotel supports 35 full-time and flexible positions worth £850,000 annually to the Inveraray economy and brings the spending power of more than 30,000 visitors to the area every year as well as providing work for 'countless' local suppliers and tradespeople.
The spokesperson concluded: 'Over the years further support has been given via the Crerar Trust charity, distributed to Argyll community projects, including in Inveraray.
'Being engaged with the local community is important for all of the group’s hotel and inns, and something Crerar Hotels is delighted to do.'
But Anne MacPherson summed up the concern of many locals as she concluded: 'All I'm looking for is to be able to continue swimming on a daily basis without having to have spa treatments.'
Yes! I would like to be sent emails from West Coast Today
I understand that my personal information will not be shared with any third parties, and will only be used to provide me with useful targeted articles as indicated.
I'm also aware that I can un-subscribe at any point either from each email notification or on My Account screen.