The new project will see old conifers that are reaching the end of their natural lives felled and replaced with native broadleaf trees such as oak, hawthorn, willow and ash.
The firm will be replacing trees on woodland bordering two trunk roads in Belmont and Burnley to prevent the trees falling into roads during heavy winds.
United Utilities woodland officer Matt Taylor said: "This scheme will ensure the safety of motorists during storms.
"The old conifers have shallow roots and are more likely to be blown over during heavy buffeting, so it's important that we take action.
"Replacing them with native trees will protect public safety, boost biodiversity and improve the overall appearance of these sites."
Work will start next week and be completed in February.
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