Ochoa's bogey stretch came in the final six holes. She finished at 11 under, three shots ahead of Nicole Castrale (68). Cristie Kerr (67) and rookie Angela Park (71) were four strokes behind the leader.
Ochoa holed out from the fairway for an eagle on the par-5 ninth. When she chipped in for birdie on the 12th hole, the top-ranked player led by six strokes.
But golf in the rain eventually took its toll.
After a lengthy delay on the 13th hole to squeegee off the green, Ochoa dropped a shot.
She then made back-to-back bogeys on the 16th and 17th holes. Ochoa had been 9-under on the par 5s at RiverTowne Country Club when she made bogey on the par-5 16th hole.
Even with the late mistakes, Ochoa remains in position to win her second LPGA Tour event in three weeks and third this season.
Tournament officials moved up tee times and sent competitors off both the first and 10th holes in an attempt to beat the drenching rain from Barry, which weakened to a tropical depression earlier Saturday.
Park, a first-year tour player, quickly opened with three straight birdies to catch Ochoa at the top.
Ochoa retook the lead on the fifth hole, rolling in a 12-footer for birdie while Park's chip to the hole skidded 6 feet past and led her to bogey.
Ochoa went three strokes ahead on the next hole with a 20-foot birdie putt. The clincher came when Ochoa's third shot on the 545-yard, ninth hole bounced past the flagstick and spun back into the cup.
She high-fived her caddie with a big grin. But she was far from finished with her run of success.
Already ahead by five strokes after Park's bogey on No. 10, Ochoa's approach shot went left of the 12th green into a collection area. Ochoa again responded by holing out, this time for birdie.
That's when things changed. Ochoa hit her tee shot on No. 13 into a bunker when the group ahead pointed out water puddles on the green. It took about 15 minutes to bring on the equipment and dry off the green.
But Ochoa's approach shot was well short of the green, leading to bogey.
Annika Sorenstam continued her injury comeback with a 2-over 74.
Sorenstam spent nearly two months recovering from a ruptured disc in her back. She hadn't played a full 18 before this week and since the Kraft Nabisco Championships.
Sorenstam, who hosts this tournament, said she woke up more tired Saturday than she anticipated and spoke with her doctor and a therapist before the round.
'It's been a long week, golf-wise, for me,' said Sorenstam, 1-over for the tournament.
Sorenstam played six holes Monday, nine on Tuesday and then '18 three days in a row. So I'm not surprised that I'm tired, that my muscles are just feeling it.'