An important salmon habitat will be protected after the multimillion-dollar purchase of an island in British Columbia's lower Fraser River by an environmental organization, with the help of the federal government and private donors.

The Nature Conservancy of Canada announced the purchase of 248-hectare Carey Island near Chilliwack, in an important ecological area between Mission and Hope known to conservationists as "the Heart of the Fraser."

The previous owners, Carey Island Farms Ltd., were using the island to grow corn.

The conservancy says Carey Island is one of the Fraser's last salmon habitat strongholds, providing gravel channels for spawning and rearing areas for salmon and other species, including endangered sturgeon.

It says Carey Island is vital for salmon because it's one of the few privately held areas of the Fraser where salmon habitat is undisturbed by the digging of dikes and ditches to prevent flooding.

The conservancy says the Carey Island purchase was made possible by contributions from individuals, foundations and other donors, with $4 million from Environment and Climate Change Canada representing almost half the total cost.

It didn't disclose the exact price.

"British Columbia's iconic salmon now have crucial spawning habitat safeguarded in the lower Fraser River, thanks to the protection of 248 hectares of island and riverbed habitat," Steven Guilbeault, environment and climate change minister, said in a statement.

"These investments through the Canada Nature Fund, working with the Nature Conservancy of Canada, are part of our national conservation campaign to protect 30 per cent of land and water in Canada by 2030."