Her winning time of just more than nine minutes and 19 seconds (9:19.96 to be exact) set a new championship meet record, bettering the 19-year-old record of 9:26.12, set in 1989 by Olympian Lisa Harvey.
About the only thing it didn't beat was her own personal best of 9:15.74, which she had just recently set on an even bigger stage - at the junior world championships held earlier in July in Poland where she finished in eighth place.
The gold medal was won by Mercy Cheron of Kenya in 8:58.07.
Needless to say, Jewett, who will enter the University of Toronto this fall, said she was quite happy with how her long season ended at last weekend's junior nationals.
"Although my time (at nationals) was a couple seconds off my time at world's, I broke the meet record set in 1989 which was exciting," she said, in an e-mail to The Mirror.
As for the world's, she termed it "an amazing experience."
"I was not as nervous as I expected. It felt wonderful to be representing my country and very exhilarating to be on the track with the best junior runners in the world. I enjoyed the entire race."
It was at a meet in Richmond, B.C., just prior to the world's where Jewett met the qualifying time - setting both a personal best time and a personal milestone.
"As making that (world junior qualifying) time was my season goal, I was quite pleased," she said.
In June, she capped off her high school career at St. Clements, which is just off Yonge Street, north of Eglinton Avenue, with a gold medal in the senior girls 3000m event at the Ontario Federation of School Athletic Associations' provincial championships. She also earned a silver medal in the 1500m event at the same meet.
"Winning the 3000m was a great way to end my high school running career and I will miss representing my high school team," she said.
Going into OFSAA, she said her confidence had been boosted by "running in the world cross-country championships in March" in Scotland. Last fall, she kicked off her final year of high school by winning an OFSAA silver medal in cross country.
She'll take a well-earned breather before lacing up her runners this fall for the University of Toronto's track program, which she is already more than familiar with.
"It is an added bonus that I will be able to continue with the U of T track program, having been a member of the U of T Track Club for five years," she said.
The U of T, likewise, considers it a bonus to have this junior national champ and Top 10 junior world finalist on board.
"The sky is the limit for her," said assistant University of Toronto track and field coach Jill Mallon, in an interview posted on the athletic department's website.
"Over the past four years, Tamara and I, as well as the other members of the coaching staff, have built a wonderful coach-athlete relationship, and I look forward to working with her as she reaches the next level of athletics. She will definitely bring a lot to our team."
Jewett, who will enter the U of T's international relations program, is equally adept and focused off the track, and has earned several academic scholarships to go along with her athletic scholarship.
She is a National AP Scholar, editor of St. Clement's award-winning literary and arts publication Papyrus and is working on her gold award in the Duke of Edinburgh program.
She also takes pride in giving back to the community, having participated in the Horizons program where students tutor and mentor other students from inner-city schools.
Both of her parents are U of T law school grads.