That came after Tap-Ky Duong was handed an 18-month jail term in Albury Local Court on Wednesday morning over offending that it was said had a considerable impact on his oldest victim.

"I find myself constantly crying in the bathroom," the girl's victim impact statement, as read-out by magistrate Richard Funston, says.

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Her experience was the only one of the three that did not involve skin-on-skin contact.

Rather, it had Duong place his hand on her buttocks on the outside of her clothing.

Nevertheless, Mr Funston described this incident, involving the girl, then 14, who worked for him, as a "very sleazy breach of trust".

"Who knows what damage it does (to the other victims, then aged seven and eight)?"

Duong must serve a non-parole period of nine months in jail, in a case that defence lawyer Mark Cronin called a "very difficult sentencing exercise".

"This is a very troubling case, a very sad case," he said.

Duong was placed on a three-year community corrections order, with conviction, over the charge related to the older girl.

Since his arrest and with the ensuing publicity, the court heard, Duong had been ostracised in the community.

A stellar reputation in his profession, built-up since he fell in love with the sport after completing his first year of a business degree at Monash University, was now in tatters, Mr Cronin said.

The two younger girls would have found it "soul-destroying" having to resume swimming laps in the pool after being touched on their genitals, Mr Funston said.

The incidents were so serious that "the only thing" that worked in Duong's favour "is his guilty plea to these charges".

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The crimes committed against the girls - aged about seven and eight - in the GT Aquatics pool in 2015, or possibly a year earlier for one of them, involved Duong putting his hand under their swimsuits and touching each girl's vagina.

"For them to have to go on another lap after that, it's soul-destroying."

Duong, who pleaded guilty to three charges of indecent assault of a person under 16, was on the spectrum for autism, Mr Cronin said, "which is consistent with my observations of him".

The court was told that while Duong, to turn 43 on March 17, initially displayed a limited insight into his offending, the pointed questioning from a psychologist was able to drag out of him a greater understanding of what he had done.

Mr Cronin said the incident in which he indecently assaulted his 14-year-old employee was on the lower end of the scale for offending.

This did not negate the seriousness of the offending, he said, rather placed it in context with respect to the other incidents that were just below the mid-range.

"It's a brief incident on the outside of her clothing."

The first girl was aged about seven or eight when she took part in lessons under Duong's tutelage in 2014 and 2015.

On one occasion, she had just completed a lap when Duong grabbed hold of her by the waist and sat her on his knee.

"The accused then moved one hand to the front of the complainant's leg ... and put his hand in under her swimwear, touching her on her vagina. His fingers would remain on her vagina until he removed them and let her go, directing her to perform her next lap."

The second girl was eight when assaulted between May 1 and September 1, 2015.

Duong held the girl around the waist after a lap, then put his right hand into her swimmers, touched her on her vagina, let her go and then told her to resume swimming.

The third girl was 14 when working an afternoon shift in August, 2018. She sought Duong's assistance to help a customer at the front desk.

After the customer left, he turned to the girl, told her "good job" and smacked her buttocks with his clipboard.

Later on, while she was at the front desk, he put his arm around the girl.

"He slid his hand down and rubbed the complainant's bottom."

EARLIER: 11.20am

A Lavington swim school owner who indecently assaulted three young girls under his supervision has been jailed for 18 months.

Tap-Ky Duong showed no emotion when NSW Corrective Services took him into custody on Tuesday at 11am.

Albury Local Court magistrate Richard Funston, who slammed the "serious" offending and called the attack on the oldest girl, 14, who worked for him as a "very sleazy breach of trust", set a non-parole period of nine months.

He agreed with defence lawyer Mark Cronin's submission that a lengthy period on parole under supervision was required for his rehabilitation and for the future protection of the community.

But ultimately, the punishment of Duong, Mr Funston said, was a greater priority.

Duong was placed on a three-year community corrections order on what was considered the less serious of three counts of indecent assault of a person under 16 years.

That charge related to Duong placing his hand on the buttocks - on the outside of her clothing - of the older of his three victims.

She was also an employee of Duong.

"This is a very troubling case," Mr Cronin said, "a very sad case."