A new landmark for renewable energy is being marked with a series of events.
It has been 70 years since large-scale hydropower - said to be one of the oldest and most reliable forms of green energy - started in Scotland.
The renewables sector has planned a year of celebrations to mark this, beginning with a Holyrood reception on Tuesday night. Industry leaders, MSPs and environmental campaigners will gather at the Scottish Parliament to mark the passing of the Hydro Electric Development (Scotland) Act seven decades ago.
Jenny Hogan, director of policy at Scottish Renewables, said the Act which was passed in 1943 "well and truly kick-started large-scale renewable energy development and brought power to the glens in the north of Scotland".
She said: "Hydropower is now one of the oldest and most reliable forms of renewable electricity in Scotland and to this day, this home-grown industry is a vital part of our country's energy mix. With around 1.5 gigawatts of hydropower currently installed, that's enough to provide almost one million homes with their electricity every year.
"This year we hope to celebrate the fantastic heritage of hydropower in Scotland and to learn from those early debates that were happening politically and publicly on how we meet our energy needs in a sustainable way that protects the environment and has a positive impact on communities."
Events include a lecture at the Hydro conference venue in Perth in May and a public exhibition of photographs and film footage taken of the construction of hydropower stations.
Peter Donaldson, director of renewable operations at energy company SSE, described hydropower as a "fantastic example of sustainability".
He said: "It was generating renewable energy long before the phrase had even been invented. It provides quality employment throughout Scotland and is proving as valuable today for energy production and the stable operation of the electricity system as it was back in the 50s and 60s.
"Our hydro heritage is something the whole of SSE is proud of, and the fact that hydro is such a significant part of our DNA is probably a major reason why sustainability continues to be one of SSE's core values. It is certainly why we are committed to major new investments in renewable energy, in all its forms, and why we are determined to maintain our position as the UK's largest producer of renewable energy."