I received an email from University Art recently (yes, that Univ Art, of which we all like to spend so much money) announcing an art contest they are holding for high school students.
The link is here.
Though here are the basic details:
Deadline: June 1st
First place: $1000
Yes, there are second and third places, too.
Categories: oil/acrylic; mixed media; watercolor; drawing(dry media)
You can get the prospectus for this at their website, along with all the details.