Water in Wheel well

Any assistance would be appreciated. I own a '98 Avalon. I went to the wheel well to get the spare when my front tire went flat. Much to my surprise there was standing water at the base of the well.



It was a surprise for two reasons: 1) no other part of the trunk was wet; 2) I don’t recall it raining recently.



Can anyone explain to me how water got in my well and how do I remedy the problem

see the sebring post