St. Louis also received a conditional fourth-round pick in the 2022 NHL Draft. The condition will be met should Brown play in at least 30 regular-season NHL games this season.
Sanford scored 16 points (10 goals, six assists) in 52 games for the Blues last season and did not score a point in four Stanley Cup Playoff games. The 26-year-old forward, who was a restricted free agent, agreed to a one-year, $2 million contract with the Blues on Aug. 4 to avoid an NHL salary arbitration hearing.
"We expect Zach's addition to prove beneficial for us in a number of ways," Senators general manager Pierre Dorion said. "He's a big man (6-foot-4, 207 pounds) who skates well, a power forward who plays with energy and a former Stanley Cup winner. As someone who's had a 16-goal season, he's very capable of contributing offensively too."
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Selected by the Washington Capitals in the second round (No. 61) of the 2013 NHL Draft, Sanford has scored 74 points (38 goals, 36 assists) in 209 regular-season games with the Blues and Capitals, and eight points (two goals, six assists) in 25 playoff games. He won the Stanley Cup with the Blues in 2019.
Blues general manager Doug Armstrong said the trade was made in part to get under the NHL salary cap of $81.5 million.
"It's as much having to get cap compliant, and in doing that, we wanted to bring back a player that we saw upside in," Armstrong said. "Logan's obviously a big man. He's 6-6, can play center and left wing, drafted I think 11th overall, so he's got pedigree. Everyone evolves and matures at a different time, and he needed a fresh start. I think Ottawa felt he needed a fresh start, and we were the recipient of being able to do that right now. So we're looking forward to getting him in here. I don't want to say where he's going to play or who he's going to play with. That's up to the coach, and that's up to Logan to get here. But our guys are familiar with him."
The 23-year-old forward was born in Raleigh, North Carolina, and played minor ice hockey in St. Louis and Indiana, where his father, former NHL defenseman Jeff Brown, was coaching.
"I definitely didn't see it coming, but absolutely I'm pumped," Logan Brown said. "I grew up in St. Louis. I've played for the junior Blues my whole life. Honestly, it's surreal. To be able to get an opportunity to play in my hometown in the NHL is what every kid dreams of."
Brown did not score a point in one game with the Senators last season and scored nine points (two goals, seven assists) in 13 games with Belleville of the American Hockey League.
"I think for Logan, the transition, not only in his personal life coming back and not having to stay at a hotel, but he can bunk back in his dad's house and then come to the rink and know a lot of the guys on the team," Armstrong said. "The long answer is, we're excited to give a young player an opportunity."
Selected by Ottawa with the No. 11 pick in the 2016 NHL Draft, Brown has scored nine points (one goal, eight assists) in 30 NHL games.
"It's definitely nice to get a fresh start," he said. "Things didn't go obviously as well as I would have liked them to in Ottawa at the start of my career, but I'm feeling great right now, I'm healthy and in good shape. A fresh start is just rejuvenating.
"They just won [the Stanley Cup], so obviously it's one of the best teams in the league. Coming in, I just want to show the coaches and the players what I can bring and to help them win games and try to go on another run."
NHL.com independent correspondent Louie Korac contributed to this report
