Councillor Peter Lewis issued the warning as he was appointed the Montgomeryshire chairman on Powys County Council.
Mr Lewis, who represents Llanfyllin on the council, thanked outgoing chairman Councillor Francesca Jump for her work over the past 12 months and warned the next 12 months would be another crucial time for the county.
He said: "It is a great honour for me to be offered this role particularly in this very important year for Montgomeryshire.
"We are about to embark on matters unprecedented for Montgomeryshire because in the next few weeks a 39-week public inquiry will begin into the development of wind turbines and their associated infrastructure.
"This represents the greatest threat in my lifetime to our county, to our landscape and environment.
"If it were to go ahead the turbines, their hub and the enormous pylons will industrialise the picturesque landscape of Sir Trefaldwyn, thousands of our constituents are threatened, no terrified of the impact of this on their communities.
"Their views must prevail."
A major public inquiry into plans to build a series of windfarms in Mid Wales will go ahead next month. The inquiry starts at The Royal Oak in Welshpool on June 4 and is due to be held in various stages, with final closing sessions due to be held in May next year.
Objectors have launched a campaign against the windfarm plans amid worries the project will destroy the landscape of the area and damage tourism.
The objectors also say the decision on whether the windfarm project goes ahead will also be key to whether a controversial power line cable is built through Mid Wales and Shropshire.
National Grid plans to build the line from a substation at Cefn Coch near Llanfair Caereinion to the national network at Lower Frankton near Oswestry.
Objectors on both sides of the Shropshire/Welsh border have joined together to form The Alliance campaign group to fight those plans.
The exact line of the power line, some of which will be carried by overhead pylons, will be announced in the autumn.