Colorado forced overtime when Forney converted a 5-on-3 power play with 10:25 remaining in regulation.
In all, Utah was called for eight of the game's 11 penalties. Colorado enjoyed a 6-2 advantage in power play opportunities, including three straight in the third period.
In the final 42 minutes, referee Andy Thackaberry called nine penalties eight on the Grizzlies.
"There will be no comment on the officiating," Utah coach Kevin Colley said, before he hurried from the locker room.
"Let's just leave it at that."
Colley was obviously upset with the turn of events, especially because Utah played as well as it has in weeks during the first period.
The Grizzlies took nine of the game's first 10 shots. They grabbed a 1-0 lead when Tommy Maxwell finished a 3-on-2 break by firing a wrist shot past Colorado goalie Adam Brown only 3:32 into the game.
"I love how we played in the first period," Colley said.
In the second period, the Grizzlies took a 3-1 lead.
At 3:36, David Eddy stepped out of the penalty box after serving five minutes for boarding and found the puck at his feet. He raced in and easily beat Brown, giving Utah a 2-0 lead.
After Colorado scored to make it 2-1, the Grizzlies regained a two-goal advantage with 4:47 left in the period when Berkley Scott deflected Eddy's wrist shot past Brown.
It wasn't enough.
Colorado scored twice in a 61/2-minute span of the third period to force overtime, where Forney won it after the Grizzly turnover.
"We lost our drive of how hungry we were, it seemed," Colley said. "It's just unfortunate."
Eagles 4, Grizzlies 3 (OT)
O Utah takes a 3-1 lead into the third period but eventually loses to Colorado in overtime.
• David Eddy tallies a goal and adds an assist, but the Grizzlies lose their fourth straight.
• Utah is called for eight of the game's 11 penalties. Colorado converts one of six power plays.