The woman drove her car through the fence of an apartment complex and into the pool, which had been covered by a tarp.
Police pulled her out of the car and pool.
"Evidently she hit the gas instead of the break and she whizzed by us, through the fence and into the pool," said Hy Speck, witness.
"She is a shorter female so the water was rising up towards her neck area," said David Heiser with Northbrook Police.
Officials said the woman was unhurt, and no residents or rescuers were injured.