"Sixteen and 17 are tough holes, especially with both pin positions, so I was very happy to hole some putts that I didn't really hole much today," Hall said. "I've got a two-shot lead. Still a lot of golf to play, but looking forward to tomorrow."
The 22-year-old Englishwoman had an 18-uner 198 total. She opened with a 66 and shot 63 on Friday.
"I definitely putted yesterday like I did at the British," Hall said. "Hopefully, I'll putt like that tomorrow as well. But I still kind of feel the same, and I'm just looking forward to playing another round of 18 holes."
Lee had a 68. The Australian lost a share of the lead with a bogey on 17.
"Just tried to play my game," Lee said. "I felt like I played pretty solid all day. Probably had one bad drive on 17 that really cost me my bogey."
Marina Alex was third at 12 under, shooting her second 71 after opening with a 62.
"It was firm today," Alex said. "The greens were really firm. The last like six holes, it was tough to just get at the flags. Once you got past 12, it's hard to get it close. I hit really good putts, too, and it was just a lot of lips. But hoping to just have a really great day and see what happens."
Brittany Marchand (70) and Ayako Uehara (70) were 10 under.
Brooke Henderson had a 74 to fall into a tie for sixth at 7 under. The Canadian star, the 2015 and 2016 winner at Columbia Edgewater, won the CP Women's Open last week on home soil in Saskatchewan.