2007-08: Nathan Lieuwen spent most of the season with the Westside Warriors of the BCHL, but also appeared in three games for the WHL's Kootenay Ice. He registered a 3.27 goals-against average while posting a .910 save percentage.
2008-09: Lieuwen appeared in just 37 games for Kootenay (WHL) due to concussion issues which prevented him from finishing the season or playing in the playoffs. Lieuwen logged a 2.95 GAA and .885 save percentage and was 14-12 with two overtime losses. Lieuwen played in the 2009 CHL Top Prospects Game, but struggled in Team Cherry's 6-1 loss. He was ranked 11th amongst North American goaltenders in Central Scouting's final rankings prior to the 2009 NHL Draft but was not selected.
2009-10: Lieuwen missed much of the season due to post-concussion issues before finally feeling symptom-free towards the end of the season. He appeared in 26 games for Kootenay with Todd Matthews handling the bulk of the goaltending. Lieuwen was 10-10 for the year with a 3.09 GAA and .896 save percentage. He appeared in three playoff games and was 0-1 with a 1.91 GAA while stopping 33 of 37 shots faced. Lieuwen was not among the 30 North American goalies in Central Scouting's final rankings and was not drafted in the 2010 NHL Draft.
2010-11: Lieuwen assumed the starting role for Kootenay in his third WHL season and after a solid regular season was even better in the playoffs during the Ice's run to the Memorial Cup. In 55 games during the season he was 33-16 with four overtime losses and three shutouts and had a 2.79 GAA and .903 save percentage. After losing two of the first three playoff games to Moose Jaw in the first round, Lieuwen and the Ice won 15 of the next 16 games. Lieuwen was named WHL Playoff MVP after finishing with a 2.24 GAA and .923 save percentage. In five Memorial Cup games he was 2-3 with a 3.18 GAA and .890 save percentage. In his third year of eligibility he was selected by Buffalo in the 6th round (167th overall) of the 2011 NHL Draft.
2011-12: Lieuwen was one of the WHL's busier goalies in his final season with the Kootenay Ice — appearing in 57 regular season games and then skating in all four games in the Ice's playoff series with Edmonton. He was 27-28, with eight losses in overtime, and had 3 shutouts with a 2.50 goals against and .914 save percentage during the regular season as Kootenay finished fourth in the Central Division. He was 0-4 in the series with the Oil Kings with a 3.53 goals against and .896 save percentage. Lieuwen signed a three-year entry-level contract with Buffalo in May, 2012.
2012-13: Lieuwen appeared in four AHL games with Buffalo affiliate Rochester in his first pro season — spending most of the year with the ECHL's Greenville Road Warriors. He was 1-2, recording a shutout for the Americans, and had a 2.65 goals against and .919 save percentage. Rochester finished second in the North Division and were swept by first place Toronto in the first round of the playoffs. Lieuwen did not play in the series. In 27 games with Greenville he was 14-10-2 with 1 shutout and had a 2.93 goals against and .903 save percentage. Lieuwen was with Rochester during the ECHL playoffs and did not play in the Road Warriors' series with Kelly Cup champion Reading.
A lanky, 6’5 goalie, Lieuwen covers the net very well with his size, though he uses his athleticism to make saves. One of the more highly touted goaltenders from the 2009 draft, Lieuwen is a potential journeyman starter or backup goalie.
The net is crowded in Rochester and Lieuwen will have to fend off Andrey Makarov and Connor Knapp for the backup job to Matt Hackett. Lieuwen split the season between the AHL and ECHL last year, but he is expected to remain in the AHL for the entire 2013-14 season.