Witter grabbed second in the 200-yard butterfly in 2:18.58 as she was edged by Ripon College's Emma Goral, who won in 2:14.06. Lawrence's Sarah Schweickart took seventh in 2:28.03.
Riggle swam to second in the 1,650 freestyle in 19:23.19 with Carroll University's Sarah Schulz winning in 19:19.06.
Riggle also took third in the 200 backstroke in 2:20.92 with teammate Danielle Millin finishing fourth in 2:21.37. Riggle posted a fourth in the 400 individual medley in 5:01.02 with Millin grabbing sixth in 5:05.31 and Schweickart taking eighth in 5:11.30.
Witter was a workhorse for the Vikings as she took third in the 100 butterfly in 1:02.34 and swam on every relay.
The 200 medley relay of Witter, Millin, Blagg and Emmi Zheng took third in 1:56.31, and the 400 freestyle relay of Witter, Blagg, Millin and Thompson was third in 3:52.20.
Zheng posted a pair of top-six finishes as she took fifth in the 200 breaststroke in 2:39.00 and sixth in the 100 breaststroke in 1:11.91. Blagg took fifth in the 200 freestyle in 2:04.35, and Lizzy Garcia-Creighton was seventh in the 100 freestyle in 57.21 seconds.
Lawrence finished third in the team standings with 656 points. Grinnell won the title with 1,466.5.
On the men's side, the top finishers were the 200 medley relay team of Max Stahl, Tom Goldberg, Christian Bell and Liam Wulfman, who finished eighth in 1:43.87. Lawrence finished ninth in the team standings with 219 points. Grinnell won the title with 1,364.5.