Any restroom facilities on Rock Springs run - King's Landing

I will be taking a canoe ride down Rock Springs Run in Wekiwa Springs State Park beginning at King's Landing. I've read that this could take a few hours to get to the marina to be picked up. I know there a some campsites along the way.

Are there restroom facilities available? Guys have it a little easier, but us girls..well. You know what I mean.