Wirt Għawdex and Għajnsielem Local Council will be appealing a project which will see a historic pumping station into a cafeteria and offices.
In a statement, both entities said they were disappointed that such an iconic structure in Mġarr Harbour and part of our national heritage was not being protected.
The site would serve far better as a small, maritime-related museum, showcasing the historical use of the building and the maritime activity right at the heart of Mġarr harbour, Wirt Għawdex pointed out.
"Managed properly, this place would have served to add much value to Gozo's sustainable touristic product, while showcasing a part of our history,” the NGO said.
"Instead, it seems that the authorities are choosing to continue to ruin our cultural heritage,” the NGO added.
The Għajnsielem Local Council said it had tried several times to acquire the premises with the intention of turning the site into an exhibition centre or a small museum.
It pointed out that such a large government-owned entity (Water Services Corporation) should have led by example and taken the opportunity to use such a building to showcase the old water distribution systems during the Knights and British era.
"The Local Council would have been more than willing to take responsibility and apply for funding to restore such a building, as it did recently by restoring the old pumping station chimney which is situated around 100 meters away and built on top of a man-made shelter in order to protect the pumping-station machinery during the World War 2 air raids," it said.
The permit (PA/07820/21) for the project was issued on Monday 19th September and the appeal will be submitted by lawyer Claire Bonello.