Science teacher Leigh Lemmon, known affectionately among the St Joseph's Catholic High School community as the 'quantum navigator' and 'rocket man', died after being pulled from the water in Yowaka River at Nethercote, near Eden, on January 4.

Just one week later, recent graduate and passionate runner Lachlan 'Lochie' Haining, 18, tragically died after being pulled from a backyard swimming pool in Albion Park.

Kembla Joggers wore black armbands at Saturday's Illawarra Track Challenge in remembrance of Lochie, who had been a "valued member" since 2015.

St Joseph's Catholic High School paid tribute to the men on social media with a gallery of photographs, including of the teacher launching rockets to the delight of pupils, and of the popular student smiling alongside his mates.

The school described Mr Lemmon as an "exceptional teacher" known for his passion and creativity. It remembered Lochie as "a kind and caring soul" who was "always inclusive and respectful" of others.

"Both Leigh Lemmon as teacher and colleague and Lachlan Haining as student and classmate participated and contributed in so many ways to the St Joseph's Catholic High School community," a Catholic Education Diocese of Wollongong spokesperson said in a statement to the Mercury.

The tragedies have left a sense of "deep sadness and shock" rippling through the school community, with extra counselling support available before Term 1 begins.

"St Joseph's has arranged prayer services during the school holiday period for staff, students and former students to gather, mourn and provide support to one another during this very difficult time," the spokesperson said.

"Additional CatholicCare school counsellors have been present at prayer services organised by St Joseph's during the holidays and will be on site again when the school year begins at the end of January.

"Free phone and in-person counselling has also been offered to current and former students throughout the school holidays."

Staff can also access free counselling support, the spokesperson said.

Hundreds of tributes have poured in for the pair on social media, as people remember their immeasurable impact on the school and their wider circles.

"Lochie was held in high esteem by local athletes and coaches. He served as a role model to younger juniors, showcasing determination and spirit in both training and racing," a post on the Kembla Joggers Facebook page read.

"We will fondly remember the presence, energy and vivaciousness that Lochie brought to his club."

More than $52,000 has also been raised in an online fundraiser for Mr Lemmon to help ease the financial burden for his family so they can "grieve the biggest support in their lives".