Kaipara Flats didn't find batting particularly easy either as Sweeney (2 for 21) and Boswell-Smith (2 for 31) made early in-roads.
Kyran Dill hit a counter-attacking 29 but Lewis Miller's four scalps (4 for 24) restricted Kaipara Flats to 135.
WBHS needed 86 runs to make Kaipara Flats bat again, however O'Flaherty proved near-on impossible to play at Kensington Park.
In just 6.5 overs, O'Flaherty tore through WBHS' batting order to end with figures of 8 for 23. This gave him an unbelievable match haul of 11 for 31.
WBHS fell for 69 to end the two-day contest early.
Meanwhile Coutts was in sublime touch for Onerahi Central against Kamo, putting in a stellar all-round performance to leave the opposition reeling.
Bowling first, Onerahi made fairly light work of their rivals as Kamo were bowled out for 105.
Onerahi bowled consistently tight with Coutts (5 for 22) grabbing a first innings five-for to put Kamo on the back foot.
In reply, big contributions from Coutts and Brad Kneebone put Onerahi in a commanding position.
The pair, who were members of the Brian Dunning Trophy-winning Northland side, punished the Kamo attack.
Kneebone made 61 while Coutts belted 131 to lead Onerahi to 300 for 9 declared.
Kamo will have their work cut out for them on day two of the contest as they find themselves six down with a sizeable deficit still to overcome.
Coutts has a chance at a 10-wicket match haul as he sits on 4 for 14 in the second innings.
Meanwhile in the first round of the reserve grade Declaration Cricket competition, Duracrete Products City and Kerikeri both picked up victories.
City grabbed an eight-wicket victory over Whangarei Boys' High School.
WBHS were bowled out for 132 thanks to a six-wicket haul from Darren Goodwin (6 for 17).
City chased down the total with relative ease on the back of half-centuries to Brad Lang (69 not out) and Harley Smith (51 not out).
Kerikeri meanwhile clinched a three-wicket win over Bream Bay.
Bream Bay batted first and were cruising at 145 for none with openers Bruce Paton (60) and Dean Gillingham (80) finding runs easy to come by.
However, Oscar McCallion (5 for 19) and Cameron Shepherd (3 for 15) ripped through the order to have them all out for 174.
Kerikeri were made to work hard for their spoils but Luke Halligan (75) and Owen Arthur (49) assured them of victory.
Onerahi Central and Kamo High played out a draw despite the former's dominance with the bat.
Onerahi made 242 from 42 overs on the back of half-centuries from BJ Howie (67), Pieter Lambrechts (62) and Ryan Woodman (60).
In reply, Kamo High defended stoutly to end their 45-over stay four down for 85.
Billy Alexander-Crawford top-scored with 39.