| 1 | Molly Winer SR | Ames | 1:04.26 | Ames High School | 09/18/2018 |
| 2 | Mary Martin SO | Dowling Catholic | 1:04.54 | Ames High School | 10/10/2018 |
| 3 | Arianna Ottavianelli JR | Bettendorf | 1:06.81 | Bettendorf High School | 10/02/2018 |
| 4 | Olivia Masterson JR | Iowa City, City High | 1:06.82 | Mercer Park Aquatic Center and Scanlon Gym | 09/15/2018 |
| 5 | Reilly Shaner SR | Valley, West Des Moines | 1:07.02 | Dowling Catholic High School | 08/23/2018 |
| 6 | Lindsey Blommers SR | Newton | 1:07.37 | Ankeny | 09/06/2018 |
| 7 | Alexis Beine SR | Bettendorf | 1:07.54 | Bettendorf High School | 10/02/2018 |
| 8 | Meghan Donald FR | Ames | 1:07.58 | Ames High School | 10/10/2018 |
| 9 | Taylor Buhr FR | Pleasant Valley | 1:07.76 | United Township | 10/06/2018 |
| 10 | Kirsti Robertson JR | Ames | 1:07.86 | Linn-Mar High School | 09/08/2018 |
| 11 | Sami Roemer JR | Bettendorf | 1:07.95 | Linn-Mar High School | 09/08/2018 |
| 12 | Lauren Tumey SR | Bettendorf | 1:08.43 | Linn-Mar High School | 09/08/2018 |
| 13 | Emma Bachelder JR | Decorah | 1:08.69 | Cedar Falls High School | 09/29/2018 |
| 14 | Christy Bishop SR | Pleasant Valley | 1:08.99 | Muscatine High School | 09/11/2018 |