Scores of people gathered for a picnic overlooking the controversial Scout Moor Wind Farm on Sunday.
The proposed expansion could add an extra 16 turbines within the existing wind farm.
Members of the public attended the summer picnic, hosted by the Holcombe Society, in front of Peel Tower to discuss their views.
Dr Falmai Binns, a spokeswoman for the Holcombe Society said: “We had a great result with our picnic and despite the weather there was a very supportive turnout.
“Again we were amazed that none of the walkers we spoke to had heard about the potential expansion of the wind farm.
“Around 50 folks joined us and there were lots of walkers who were very interested in the potential development and most distressed as they all treasured this exceptional viewpoint and were astonished to hear it was further threatened.
“One little girl felt so strongly that she gave up her birthday to join us.”
The plans for more turbines is a joint venture by Peel Energy and United Utilities.
Jon England, a spokesman for Peel Energy, said they had amended their plans in the wake of feedback from their public consultation last summer.
He added: “There have always been good reasons for expanding the existing wind farm such as a proven track-record of high energy output and the fact that we have an existing point of access.
“The expansion also presents an opportunity to build on our relationships with surrounding communities, providing much needed funding for a range of initiatives and using the wind farm as a valuable resource for recreation and education.”
Residents are invited to a meeting, hosted by former BBC TV presenter Martin Henfield, tonight (June 18) at Ramsbottom Civic Hall, at 7pm to discuss the plans.
People can submit their views to Rossendale Council by e-mailing firstname.lastname@example.org (citing ref 2015/0112)