At St Clair, the senior team beat Southland 6.5-3.5 and Aorangi 5.5-4.5 to take the trophy with four points and 12 games.
Aorangi did not enter an under-21 team, leaving Otago to battle singles and reverse singles against Southland with Otago winning 8.5-3.5.
The weather was no better in Invercargill where the Otago Masters (over-40) team finished in second place behind Southland on the Otatara course which will be the venue for the national masters tournament this year.
The Otago tail of Luke Murdoch, Simon Hollyer and Chris Snow paved the way for the senior win with all three players notching two wins in the event.
In addition to them, Hamish Ireland and Thomas Facer emerged unbeaten with a win and a half apiece.
There was a word of warning for the top five with Otago halving with Southland and going down to Aorangi by a 3-2 margin.
This event is one of the build-up tournaments on the way to selecting the top five for the national event in December.
The feature game on Saturday afternoon was between Otago No 1 Brent McEwan and South Island under-19 champion Tim Leonard (Aorangi).
Despite the conditions, Leonard birdied the first two holes but McEwan rapidly responded with five birdies in the next seven holes to turn in 30.
His low boring knock-down shots were ideal in the conditions and he kept Leonard out of contention, the match finishing on the 17th green.
Otago No 2 Duncan Croudis lost on Saturday afternoon to Liam Balneaves in 15 holes but was having difficulty swinging and was forced to withdraw, putting reserve Chris Billington (Balmacewen) into No 2 spot yesterday morning.
He competed well but lost the final hole to Aorangi's Daniel Perham, to halve the match.
