Stickle Tarn has been listed as an Asset of Community Value.
The move means community groups would now have six months to put together a bid to buy the tarn if it goes back up for sale.
David Sykes, Director of People and Places at South Lakeland District Council, said the decision to list the site was made because it 'serves local social interest and wellbeing'.
Last month, the deadline to bid on the land passed.
However, Lake District National Park Authority rejected tender bids as they didn't believe they were "responsible" enough.
Campaigners have objected to the potential sale of the site, with thousands supporting a Save Stickle Tarn group.
Park bosses first announced they were selling the tarn, along with six other areas in the National Park, in February this year.
Watch Fiona Marley Paterson's full report on the protests over plans to sell parts of the Lake District:
Campaigners are protesting against the potential sale of seven Lake District beauty spots.
The group 'Save Stickle Tarn - and our beautiful Lake District' has been demonstrating outside the LDNPA visitor centre, in Brockholes,
They also staged a walk at Stickle Tarn, in protest.
The group says:
But the Lake District National Park Authority says the lands will still be subject to the same public access rights and restrictions, meaning the sales pose no danger to the environment or public use of the land.
It argues that once it has improved access and conservation on sites it is common practice to return them to the private market, where they can still be managed by the National Park's planning processes.
The National Park Authority has had its funding cut by 23% in the last 5 years and intends to use the £500,000 from the sale for other capital investments.
The deadline to bid for seven of the Lake District's best known beauty spots is up today.
National park bosses are selling off the Stickle Tarn with a guide price of twenty to thirty thousand pounds.
The other areas up for sale are:
- Yewbarrow Woods
- Blue Hill and Red Bank Wood
- Blea Brows
- Baneriggs Wood
- Land near River Derwent
- Waterside Knott
The Lake District National Park Authority has put seven sites up for sale, including the iconic Stickle Tarn.
The Tarn's well known to fell walkers, set within the Langdale Pikes, 1,500 feet above sea level - and three miles west of Grasmere.
It has a guide price of between £20,000 and £30,000 and is already attracting interest.
But not everyone is pleased it is up for sale.
Our correspondent Hannah McNulty made the hour long hike up it to find out who may want to buy it.
The swimmers in the piece are professionals and were being supervised and were only in the water for a short amount of time.
One of the Lake District's best known beauty spots is being sold off by park bosses.
Stickle Tarn, in the Langdale Pikes, is one of seven areas that has been put on sale by the Lake District National Park Authority.
It is on the market with a guide price of between £20,000 and £30,000.
Local MP Tim Farron has called for a decision regarding proposals to extend the boundaries of some national parks, including the Lake District National Park.
The proposals were first set out by Natural England in 2011 in a bid to increase the areas that can be conserved.
However, some residents and business say that if passed, the proposals would mean much tighter planning regulations.
Last year, a public inquiry was held after five councils, including Cumbria and Eden District , opposed the changes.
Mr Farron says the current uncertainty over the plans is worse than either outcome and has called for a decision to be made.
We may be in the middle of winter, but the Lake District National Park Authority is asking ice cream sellers to bid for the best spots ahead of the summer season.
15 million people come to the lakes every year and good pitches for ice cream vans can be a big money spinner for the ice cream sellers.
They have until the end of the month to apply.
The Lake District National park is on the hunt for volunteers.
They're looking for 30 people aged 18 and over who want to improve their countryside and environmental skills while gaining qualifications along the way.
Backing from the Heritage Lottery Fund has meant the Lake District National Park is able to recruiting volunteers for their Fell Futures project.
Volunteers will work alongside members of staff in an attempt to revive dwindling traditional skills and train the next generation of countryside workers.
Experience is not necessary but a reasonable level of strength and fitness will be needed carry out some of the more demanding jobs.
To find out more you can visit the Lake District National Park website.