Minnesota men’s hockey defenseman Erik Johnson announced yesterday he will forego his final three years of eligibility to join the St. Louis Blues next season.

Johnson, 19, who was selected No. 1 overall by the Blues in the 2006 NHL draft, said the decision was in the works for much of the week.

“I informed Blues President John Davidson Tuesday morning,” Johnson said. “They kind of had contract negotiations going on, but I officially announced it (yesterday).”

Johnson said he couldn’t discuss the specifics of his contract at this point, but said it will be in the nature of a three-year deal worth $765,000 per season with an undisclosed signing bonus.

In one season with Minnesota, Johnson raised eyebrows with his six-feet four-inch, 222-pound frame. His physical presence on the blue line and deep in the defensive zone gave the Gophers a boost in grittiness, something they lacked in past seasons.

And with his keen sense for threading passes to forwards streaking up ice, coupled with a nasty slap shot, Johnson amassed four goals and 20 assists in his one season with Minnesota.

“On the ice, he’s just a great competitor and brings that physical presence,” defenseman Derek Peltier said. “He’s strong in his own end – hits and pins well. But he also sees passing lanes and has that booming shot.”

Peltier, who will be a senior next season, was unaware of the move until yesterday afternoon, but said Johnson will be missed on the blue line.

Other teammates contacted Johnson to wish him well.

“A lot of them are really, really happy for me,” Johnson said. “I’ve gotten calls from five or six of them.”

Johnson felt similar sentiments toward his former team.

“I had a tremendous time at Minnesota,” he said. “It was one of the best teams I’ve been on skill-wise and with the coaches I had, but I felt it was time for me to move on.”

Though the move was expected, coach Don Lucia said in a prepared statement that Johnson’s departure is “bittersweet.”

He said Johnson was one of the most talented defensemen he’s ever coached.

“Erik was immediately an impact player in our program,” Lucia said. “There is no doubt in my mind that Erik will have a terrific career in the NHL.”

As a highly touted player at the Academy of Holy Angels in Richfield, Johnson quickly moved on and made an impact on the U.S. National Development team based out of Ann Arbor, Mich.

He decided to attend Minnesota instead of jumping straight to the NHL, saying earlier in the season that he knew he wasn’t quite ready for a leap to the professional ranks.

But after a season with the Gophers, which included accolades such as being named to the Western Collegiate Hockey Association All-Rookie Team, Johnson said the time was right.

While Johnson became the first Gophers defenseman to pass up remaining eligibility for the NHL since All-American Keith Ballard in 2003-04, he might not be the only one to do so this offseason.

Defenseman Alex Goligoski and center Kyle Okposo are both likely candidates to leave early, along with Johnson, but neither has publicly made that decision.

If Goligoski and Johnson both go, coupled with Mike Vannelli’s graduation, Minnesota will lose its top three scoring defensemen.

“It’d be fun to give (other younger defensemen) an opportunity to fill those roles,” Peltier said. “We’ve got guys itching to get that chance.”