The visitors faced a daunting chase but were spared, as the rain returned to have the final say.
The match was abandoned and each side added a further two points to their total. But that will be no consolation for the Sparks, who were targeting a bonus point win to help close the gap on the top two sides.
The result has left Otago in fourth place with 13 points. There are a maximum of 15 points still on offer but Otago's chances of making the top two have reduced.
Canterbury leads with 28 points with a game in hand. Auckland is second with 21 points, with Wellington third with 20. Northern Districts (6) and Central Districts (2) are out of contention.
Frustratingly, Otago has had two abandoned games, both against the two bottom-placed teams.
The Sparks can reflect on a good effort with the bat yesterday, though. They went into the game without star players Suzie Bates and Morna Nielsen, and in-form all-rounder Victoria Holden sat out the match with a neck complaint.
But opener Millie Cowan seized her opportunity and slapped a career-high 48 from 43.
She got her innings motoring with four consecutive boundaries in the sixth over.
Fellow opener Leigh Kasperek perished early to a cracking catch at first slip. But captain Katey Martin (34 from 38) combined with Cowan to add 81 for the second wicket and set up a decent platform.
Polly Inglis (14), Caitlin Blakely (19) and Megan Gibbs (12) all made useful cameos, and towering left-armer Kate Heffernan showed she can bat, lofting a beautiful drive down the ground for the game's only six. She scored an undefeated 20 from 10 deliveries but the rain returned and the game petered out.
Spinner Kate Anderson was the pick of the visiting bowlers with four for 32.
In the other matches, Wellington beat Auckland by four wickets in a twenty20 match, while Canterbury crushed Central Districts by seven wickets in a rain-affected one-dayer.
In Wellington, the Otago Volts had an exciting finish to their disappointing twenty20 campaign.
Rain reduced the game to a five-over affair and Otago posted 48 for one. Hamish Rutherford cracked 24 from 14 deliveries.
Wellington lost three consecutive wickets during its reply but needed just eight off the last over to win.
Top order batsman Ryan Duffy was called on to bowl the final over and did remarkably well, restricting Wellington to seven runs and forcing a super over. Wellington's Luke Woodcock was run out trying to steal a second run off the final ball to win the game.
The super over proved one-way traffic, as the home side smashed 20 for one. Michael Pollard hammered two sixes and a four off Neil Wagner's over.
The Volts could manage only eight runs for the loss of two wickets in its super over. Wellington won by 12 runs and sealed a playoff spot.
In the other twenty20 match, Auckland amassed 212 for four at Eden Park Outer Oval. Twenty-year-old Glenn Phillips smashed 116 not out from 57 balls to register his first century in the format. Central Districts was 82 for none when the rain arrived and won by 11 runs by the Duckworth-Lewis-Stern method.
The Central Stags are through to the final and Canterbury and Wellington will meet in the preliminary final tomorrow.
