SANTIAGO, July 24 (Reuters) - World No. 1 copper producer Codelco submitted to Chilean environmental authorities changes to its controversial Andina project that it said would reduce the mine's potential impact on nearby glaciers and water supply.

State-owned Codelco, which produces about 10 percent of the world's copper, has said its future hinges on the development of the project, as dwindling ore grades in its old mines will bring annual output tumbling down.

The $6.8 billion expansion project, which seeks to push up the existing mine's total production to 600,000 tonnes of copper annually, has come under fire from environmentalists due to concern over possible environmental impact.

"We've worked for over a year to consider each of the comments we received, holding dozens of meetings, workshops, listening to the community, authorities and experts," said Rene Aguilar, Codelco's vice-president of corporate affairs and sustainability, on Thursday.

"Today we have a better project, with more information and new measures that address the main concerns and that reduce the project's impact on its surroundings," he added.

The project will also look to recycle on average 65 percent of the water used at the new operation.

"Two out of every three liters of water that the Andina expansion needs will come from recycled water, making the project very efficient in terms of water resources," said Codelco's acting projects head, Gerhard von Borries.

The headwaters that flow through the mine's area feed the water supply in Santiago and the surrounding agricultural region of the Aconcagua valley.

"We've changed the layout of the open-pit mine, which allows us to reduce the number of rock glaciers that will partially be affected," von Borries said.

Five so-called rock glaciers will be partially affected but no white glaciers will be, he said.

(Reporting by Anthony Esposito; editing by Matthew Lewis)