No water during run, but still did 2.25 miles

I was on the Parkway path at 10 am. There was a significant amount of shade, and I appreciated it. I didn't carry water, because the shade temperature when I left home was 80 (F). I did fine until about half way back when I because thirsty. I only had 1/2 mile left in my run, and I hung on without water until I reached the parking lot and had a good drink of water. I used a ratio of 80:60 for most of the run, but I used 80:70 for part of the run.