Inkster, a two-time winner of this event, shot a 3-under 68 and is one stroke ahead of Christina Kim, who also posted a 3-under 68 on Saturday. Kim is alone in third at 12-under-par 201.
Lindley, who gave birth to her first child earlier this year and returned to the tour in June, birdied the fourth and fifth holes to move up the leaderboard.
She collected back-to-back birdies at the 10th and 11th holes that gave her the lead, but then dropped a shot to par at the 13th and fall behind both Inkster and Kim.
But Lindley had one more run of good golf left in her. She birdied three in a row from the 14th to jump into sole possession of the lead, a spot she wasn't sure she would be in so quickly after the birth.
'I didn't anticipate playing as well as I have this year,' said Lindley, who is winless on the LPGA Tour. 'I've had two top 10s, and I didn't know what to expect. Maybe he's good luck for me.'
Inkster had her share of problems on the front nine, as she tallied one birdie at the fifth and a bogey at the par-5 ninth.
On the back nine, Inkster collected three birdies in a four-hole span to reclaim her top spot on the leaderboard. Lindley made more birdies down the stretch, but Inkster, a Hall of Famer, is in position for her first win of the year. Inkster has won at least one tournament a year for the last seven years.
Kim, the first-round leader, got out quickly with three birdies in her first five holes. She bogeyed No. 11, when she needed two shots to get out of a fairway bunker.
Kim, who is winless in two years on tour, birdied the 14th to get within two of Lindley's lead.
Katherine Hull fired a 65 on Saturday and is tied for sixth place with Michelle Estill and Angela Stanford, both of whom shot 70s in the third place. The trio is knotted at 9-under-par 204.
Hee-Won Han, who won last week's Safeway Classic, carded an even-par 71 and shares ninth place with Donna Andrews, who shot a 67 on Saturday. The duo is tied at 8-under-par 205.