Collies claimed last year's premiership in a canter, but just months on could not find enough players to constitute a viable squad for 2024, with a combined Southern Corridor competition to feature just three Illawarra clubs.

Thirroul, Wests and Corrimal will contest a Southern Corridor 'gold' premiership against Shire clubs Kingsgrove, Aquinas and Bosco, while a composite Port Kembla-Dapto side will contest the second division 'silver' competition.

The inability to maintain a standalone under 18s competition in the Illawarra again casts doubt on the future of the top-grade competition that has been unable to sustain more than six teams with any regularity over the past decade.

While the Illawarra Steelers junior male and female pathways are in a state of rude health, for a rugby league heartland to be unable to field its own under 18s competition casts doubt on the future of its storied top-grade competition.

While he concedes the struggle to convert players from the junior to senior ranks is "most definitely" a concern, Illawarra DRL head of football Brent Pigram said it's not a challenge unique to the Illawarra.

"When we had the team nominations, five came through, which included a combined team in Dapto and Port Kembla in the under 18s," Pigram said.

"Straight away, the biggest concern was running the small comp and having a competitive balance. It was really important we were trying to achieve that.

"Around mid-March we had some initial discussions with New South Wales Rugby League and Cronulla around the [potential] Southern Corridor competition [options] that exist there.

"Last week Collegians pulled out of that so now [Illawarra] have four teams in that competition. The conversations with Collegians were around player numbers and around team staff in particular.

"It's most definitely concerning, but it's interesting that Cronulla has dropped four or five teams this year as well, so it's not a problem that we're encountering alone."

The Southern Corridor option is a solution to ensure Illawarra teams could field under 18s sides this season, but Pigram said the divisional structure is primarily aimed at long-term sustainability and addressing the sharp drop in players progressing from the junior to senior ranks.

"From our point of view, it's a short-term pain for a long-term gain," Pigram said.

"This year, we only had five and that wasn't going to change locally, so our preference was to make sure that there was divisional footy offered. It's a long term solution to a problem that's not just isolated to here.

"I think from my point of view, the biggest thing we need to do is show that there is a competition there that's divisional, that a [under] 16s [division] two from this year can easily jump into for next year. It's one that's across the corridor.

"We want to get this established, lock it in for next year, which has already been discussed, to continue that Corridor competition.

"The biggest thing from my point of view is to try and show what competitions are going to be on offer next year to retain as many players as we can for the following year."

Collegians president Bruce Prior admits he's at something of a loss to explain the downward trend in player numbers in the Under 18s division, with the Dogs forced to drop out just a year after claiming the title.

"It's not ideal, but at the end of the day it's just a pattern that's developed over a period of time and I honestly don't know what the answer is," Prior said.

"Two years ago Dapto won the Under 18s (premiership) quite convincingly, but this is the second year in a row that they can't field a side either. Now we've won the comp and it's happened to us.

"We had probably 14 players, but we had a couple of injuries that were season-ending. You need a minimum of 19 players to kick the competition off because you're going to get injuries, you get a couple of guys drop out.

"[Illawarra's] supposedly a [rugby league] stronghold, but not anymore. You can only imagine what it's like out in the bush, and I honestly don't know what the answer is.

"Employment conditions have changed. If you get an apprenticeship the boss says 'mate, if you get hurt playing sport there's another bloke who'll walk in that door as you're walking out' and these kids need to make a quid.

"As long as I've been in the game, I don't know what the answer is, but it needs to be sorted out pretty quick because it's just a trend now, kids playing sixteens are not coming through.

"Unless you've got kids coming into grade, the competition's just going to fall away."

It comes amid a flood of transfer requests for players to switch to neighbouring Group Seven, which currently fields an 10-team Under 18s competition feeding into first and reserve grade.

While the Illawarra and Group Seven competitions are merged up until Under 16s, adding a combined Under 18s competition would not easily align with the South Coast competition's traditional three-grade structure.

With three of the eight clubs contesting the Illawarra reserve grade premiership not fielding top-grade sides, resources of first grade clubs are already stretched across multiple days and venues.

There are few other options at the IDRL's disposal, but there are fears the structuring of Southern Corridor competitions will amount to the effective break-up of Illawarra clubs.

"This weekend we've got Dapto in first grade at three o'clock at Dapto Showground and our reserve grade's playing in Berkeley at three o'clock," Prior said.

"You can't sprinkle a bit of magic dust on your blue shirts or your strappers and be in two places at once. It's just impossible because the clubs haven't got that many volunteers to go around.

"We're all between a rock and a hard place. I just don't know what the answer is.

"If this [corridor] works it works. If it doesn't, we've just got to go back to square one."