Alright, so I implemented nigathan's solution, and it worked perfectly, so thank you!
However, I've still trying to figure out how to disable water spread locally in an area. I used a fill command for the area in question, changing flowing water into stationary water, figuring that would prevent it from spreading. Nope. I then tried changing all flowing water into air, but that also changed all stationary water into air. So I'm rather baffled at the moment. Thoughts?