Edmonton city council has approved a land zoning change for a contentious solar farm next to a water treatment plant in the city's river valley.

The 51-acre project from Epcor will be located near the E.L. Smith Water Treatment Plant, in a southwest section of the river valley.

The solar farm, which includes about 45,000 solar panels, will have a peak generating capacity of about 12 megawatts.

The rezoning passed with a 7-6 vote Monday night, following a public hearing involving dozens of speakers.

The project was discussed before council last year, but was sent back to administration for review after a public hearing.

Epcor agreed to make some changes to the plan, including reducing the project's footprint by almost 20 per cent, and designating space along the riverbank for wildlife to pass through.

At Monday's public hearing, several councillors discussed the difficulty of the decision; balancing the city's green energy goals with the need to protect the river valley.

"It's tough because to me, this is a case of wanting to do all the right things, but it's coming out just a little bit wrong," Coun. Aaron Paquette told council before the vote.

Mayor Don Iveson voted in support of the rezoning application along with councillors Moe Banga, Bev Esslinger, Ben Henderson, Sarah Hamilton, Tony Caterina and Michael Walters.

The six councillors who voted against the application were Paquette, Tim Cartmell, Jon Dziadyk, Andrew Knack, Scott McKeen and Mike Nickel.

"I would not support putting solar panels throughout seven thousand acres of the river valley" said Iveson. "But next to water treatment plant on land that is reserved for its expansion, that's previously disturbed, on a temporary basis, to help us reach our climate goals — makes sense to me."

Dziadyk said for him, the decision was about the need to protect the river valley. Approving the solar farm could open the door to more development down the road.

"I am concerned that there will be more development and the justification for that will be based on the decision here," he said.

Epcor already has approval for the project from city administration, the Alberta Utilities Commission and Alberta Culture and Tourism and signed a memorandum of understanding with Enoch Cree Nation last month.