Layla Atherton, 12, Miette Hopper and Bella Geue, both 11, will be the first Horsham swimmers in five years to compete at the championships.

Since 2009, some Horsham Sharks juniors have swum times fast enough to qualify for the championships but were unable to compete or chose not to.

The competition starts on Friday and concludes on Sunday at the Wodonga Waves swimming centre.

It is the premier long course swimming competition for swimmers in country Victoria, and features athletes from more than 40 swimming clubs across the state.

Atherton qualified in the 12-year-old 100-metre butterfly, Hopper in the 11 and under 50-metre butterfly, freestyle and backstroke and Geue in the 11 and under 50-metre freestyle and backstroke.

The three train several times a week at Horsham Aquatic Centre with multiple coaches.

Coach Paul Atherton -  who is also Layla's father - said the swimmers' qualification had come as the result of hard work.

"The girls have put in a lot of extra training and lots of work to get to this level," he said. "We used to have quite a strong culture of swimmers going to the state championships but in recent years there haven't been as many so we're trying to build that back up again.

"Hopefully they inspire others in the club and the district to try to reach that level."

To qualify for each of their events, the girls had to swim below a time specified by Swimming Victoria in each stroke at one of several official qualifying meets in the past year.

The girls said they were all nervous about swimming at the state championships for the first time, but also excited.

"I've only ever been in club meets before so I'm pretty nervous," Atherton said.

"People at some of the other clubs train eight times a week and I only train five times a week so that will make it tough.

"I still think I can beat them though."

Hopper said she also found the idea of swimming at the championships daunting but was ready to

have a go.

"I think it will be big and pretty challenging, but I haven't really thought about that too much," she said.

Geue said she had no idea what the competition would be like.

"It's sort of scary and challenging, but I'm ready for it," she said. 

Horsham Sharks coach Jenny Ough said the club was extremely proud of the efforts of the girls.

She said the club could have a new influx of juniors swimming at the state level.

"They're swimming at the long course country championships but we also have short course championships which are usually in August," she said.

"These girls have made the long course event and we should have even more qualify for short course later this year, so that's looking extremely promising.

"We're really getting the club on the right track."