A picturesque little Ontario town is hunting for an extremely rare dragonfly believed to live on a local river in hopes that finding the endangered species could kibosh construction plans on the waterway.

But experts say that only about 200 rapids clubtail dragonflies exist in all of Canada, and only 20 to 30 of the insects could be living on the Mississippi River in Almonte, Ont.

The town’s mayor has helped lead the fight against the expansion of the Enderdu Generating Station, located on the river, for the past four years. He has even reached out to Environment Minister Catherine McKenna in a last-ditch plea intervention.

“They’re found in only four rivers in all of Ontario. This is probably the best river for them. They’ve been found in three different spots in this river, most recently right here,” Shaun McLaughlin, mayor of the municipality of Mississippi Mills, told CTV Ottawa from beside the river.

So far, the rare dragonfly – known for its distinctive yellow markings and blueish-green eyes -- has remained elusive. An environmental report from Enderdu, the company behind the generating station expansion, said that they haven’t found a single one of the insects.

The dragonfly is listed as an endangered species in Canada, which means it faces imminent extinction. They are believed to live in four rivers in Ontario -- the Thames River, the Humber River, the Credit River and the Mississippi River – and are threatened by the degradation of water habitats.

Locals have waded into the water to search for the dragonfly, but the chances of finding one become slimmer by the day. Experts say that adults only live for about four weeks each year in June to mid-July, and the peak time to find them has passed.

A local biologist who has spoken out against the expansion project says, because of the development, the river is “no longer a habitat” for the insects. He has also raised serious questions about how the environmental report was conducted.

“The environmental assessment for this, I believe, was very deficient, in my opinion,” said Joachim Moenig, a retired environmental biologist for the Canadian government.

The environment minister has yet to respond to the mayor’s plea for help, but McLaughlin said he’s still optimistic for the project to be put aside in hopes of protecting one of the few remaining dragonflies.

“It’s not over ‘til it’s over,” he said.

With a report from CTV Ottawa