The South Island beat the North by 52 points to 47 to win the Leith Menzies Trophy.
McBride won her single sculls convincingly in a time of 8min 2.77sec, 7.3sec in front of North Island sculler Ashlee Caskie.
McBride also stroked the quadruple sculls that won both races, the first in a time of 7min 7.86sec and the second in 7min 4.07sec.
The Kavanagh College pupil has been unstoppable since winning three gold and one silver medal at the Maadi Cup regatta at Lake Karapiro early in the month.
But the South Island was not as fast as the North Island in the girls' sweep oar events, where Johannah Kearney of Oamaru was in the crew.
The New Zealand University rowing championships at Lake Karapiro was won easily by Otago University with 273 points.
The strength of the Otago crews was in the women's events and this was highlighted by the Otago University eight, which retained the Tamaki Cup for the fifth consecutive time and the ninth time this century over the 3.2km course.
The women's eight of Jenny Storey, Bea Heaphy-Hall, Lindley, Elyse Fraser, Kirsty Thompson, Hayley Jenkins, Laura Tester, Lisa Owen and cox Aynsley Moore won in a time of 10min 8.56sec, from Otago's second crew 10min 11.56sec and Auckland, third in 10min 28.43sec.
The women's intermediate eight beat Auckland in a time of 6min 58.19sec.
The Otago University men's eight failed to win back the Hebberley Shield that it lost to Canterbury University last year. It was won by Waikato University for the first time since the race was first held in 1928.
But it was a different story in the men's four, won by the Otago crew of Michael Nisbet, Alistair Bond, Mark O'Connor, James Harvey and cox Michael Dessoulavy, by 7sec from Waikato.
The novice squad from Otago was also dominant and won the men's and women's fours and eights.
The race of the day was the men's intermediate eight, where just 0.12sec separated first and third. Auckland won in 6min 11.57sec from Otago, 6min 11.67sec and Lincoln, 6min 11.69sec.
