United Utilities has launched a forestry management project above the closed A591 in Keswick, in order to help prevent future land destabilisation.
The company is felling some of the tall, non-native conifers on the steep eastern banking above the road, which are at risk of becoming unstable.
These will be replaced over time with a more diverse range of species, more suitable for steep ground and providing a more resilient cover against extreme weather.
United Utilities is taking advantage of the current closure of the flood damaged road to carry out the £500,000 project - but has stressed it will not delay any reopening.
Vicky Bowman, United Utilities' woodland officer, said: "The trees we are taking down were planted several decades ago, but unfortunately, are inappropriate for the steep ground and skeletal soils on the slopes above the road.
"Their height makes them vulnerable to the wind, which can cause roots to be ripped up, resulting in soil erosion, and the risk of trees falling into the road in extreme weather.
"We'll be replacing them with a more diverse range of species, which will hold the soil together more effectively, and be more resilient to heavy rains.
"Under normal circumstances, we'd have to carry out this work at night, but the current road closure gives us the opportunity to get it done now. The work will help ensure that when the A591 is back open, it stays that way."
Planting will take place during the next planting season. In the meantime, roots of felled trees will be left in place, in order to protect soil. The work is supported by the Forestry Commission and Cumbria County Council, and is part of United Utilities wider forestry management strategy for the catchment land around Thirlmere reservoir.