Allysa Vavra's outstanding year in the pool reached new heights on Thursday at the 2011 ConocoPhillips USA National Swimming Championships at Stanford University's Avery Aquatic Center.

Vavra turned in her best-ever performance at a national meet when she finished fourth in the women's 400 IM championship final.

Vavra, a Panther Valley High School graduate, qualified for the final by turning in the third best time of 143 swimmers in Thursday morning's prelims, finishing in 4:42.45. Vavra entered the event seeded 21st, but her prelim time was over five seconds better than her seed time.

In the finals on Thursday night, Vavra had a time of 4:43.98. Elizabeth Beisel finished first in 4:34.78, Madeline Dirado was second (4:37.88) and Natalie Adams (4:42.99) was third.

Earlier in the meet, Vavra had finished in second place in the "B" final in the 200 IM.

The top swimmers from around the nation, including nine U.S. Olympians, are competing at Stanford this week. The event is serving as the selection meet for the 2011 Pan American Games, which will be held Oct. 15-22 in Guadalajara, Mexico.

Vavra's strong showing at the meet comes on the heels on an outstanding performance at the 2010-11 Big Ten Championship meet held in February at Indiana University. In that meet, Vavra captured gold medals in both the 200 IM and 400 IM as a member of the host Indiana swim team.

In addition to Vavra's performance on Thursday night, Northwestern High School senior Madison Burns also had a strong showing. Burns entered the meet seeded 91st, but swam a 4:56.49 in the prelims to place 66th.

The 2011 ConocoPhillips USA National Swimming Championships will conclude Saturday.

Today, Marian High School graduate and current University of Georgia standout Kristen Shickora will be in action in the 200 backstroke. Shickora is seeded 38th out of 206 qualifiers in the event. The 200 back prelims are in the noon session today. The finals are in tonight's 9 p.m. session.

Shickora captured first place in the "B" Pool in the 100 backstroke on Wednesday. She narrowly missed qualifying for the championship final, finishing one place and one hundredth of a second out of the top 10 during the prelims.

On Saturday, Vavra is scheduled to return the pool in the 200 breaststroke. She finished third at that event at the Big Ten Championships and enters this meet seeded 64th out of 157 swimmers. Prelims for the 200 breaststroke will be held during the noon session. Finals for the event will be during the 9 p.m. session.