The sand is soft, the sea warm and shallow, and at three low-key beach shacks, barefoot holidaymakers pay a few Turkish lira to drink tea, water or cold Efes beer under a corrugated iron roof. The peckish can order a gözleme (Turkish pancake) filled with cheese, spinach or mince from another green-painted shack, where local women roll out the flatbreads to order for 8 lira (just over £2). Down on the sand, a wicker sunshade and two basic loungers cost £2.50 a day. At intervals along the shore, wire cages with scrupulously observed “do not disturb” notices indicate the presence of turtle nests.

June Haimoff of the Sea Turtle Conservation Foundation, who helped to win environmental protection status for Iztuzu beach in the late 1980s. Photograph: Liz Boulter

This is Iztuzu, or turtle, beach, in south-west Turkey, beloved by holidaymakers staying in the riverside town of Dalyan, 13km inland, as well as by day-trippers from Marmaris, Fethiye and Ölüdeniz. This is the beach that was famously saved from development in the late 1980s thanks to the efforts of “Kaptan” June Haimoff, the Englishwoman who lived in a hut here from the mid-1970s (and still lives in the area). She managed to see off a plan to turn this 5km of unspoilt paradise – and nesting site for loggerhead turtles – into a resort with large-scale hotel, yacht marina and dozens of holiday villas.

Yet 25 years after the doughty June, now 91, battled with an international property consortium to win special environmental protection status for the beach – the bulldozers were lumbering into position as she fought – the 5km delta spit could once again be under threat.

Changes to local government boundaries this year have seen Dalyan and Iztuzu beach come under the aegis of nearby Ortaca district, and the licence to run beach facilities being sold to Oruç, a Turkish/British company of carpet merchants and property developers. June – and her Turtle Conservation Foundation, started in 2011, the year she was awarded an MBE for her environmental work – are, of course, not taking this lying down. There is an online petition calling for cancellation of the licence.

The unspoilt sands of Iztuzu Beach. Photograph: Alamy

Interested tourists might spot June as she takes a glass of tea at the bar at the southern end of Iztuzu. With a cut-glass accent and Vanessa Redgrave manner, she submits graciously to requests for photos, but is determined to go on fighting the good fight. “Oruç see this beach as a wasted opportunity,” she said, indicating the basic tables and benches. “They will knock this down and put in something much more upmarket: expect plate glass and overpriced tea.”

However, Louise Marie Hollis, property sales manager for Oruç, stressed that while the company is planning to knock down the shacks once the season ends next month, it is with a view to improvement, adding facilities for children and disabled people. “There will be better food, new sunbeds are on order because the existing ones are a bit shabby, and there are plans for more wooden walkways to protect beachgoers’ feet from the hot sand. There may be a small increase in the prices charged.”

Ever-vigilant for the welfare of her beloved kaplumba (turtles), June and her foundation also persuaded the Ankara government earlier this year to make illegal the common practice of baiting turtles with their favourite blue crabs for the entertainment of tourists at the seaward end of the Dalyan channel. Enforcing the law is another matter, however – the baiting was as popular as ever this summer – and June is also campaigning for all boats in the channel to be fitted with (free) propeller cages to prevent injury to turtles.

Dalyan townspeople are generally supportive – the municipality has run the beach shacks for 16 years now – but she struggles to get the boatmen on side. “They say the propeller cages are a thing they’ve never used. They say they’re not worried about killing or hurting turtles because more will come.”

They’re wrong about that: sea turtles are one of our oldest species, roaming the earth’s waters for around 100m years. But the 21st century has seen numbers declining by up to 7% a year.

Present regulations mean Iztuzu beach is out of bounds at night between May and September, and no umbrellas or beach towels are allowed on a crucial strip close to the waves, where turtle eggs lie incubating for several months. With a natural paradise this precious, for humans and reptiles, concern at commercial involvement is understandable. As the petition says: “Whose beach is Iztuzu, and whom are you handing it to?”