Tracy has some very good points...one thing I learned about ag lime is it reacts very slowly, so it won't harm anything when its laying around or water washes it into the pond where a wash is. Slow is good. I don't think you'll harm anything, any way you do it. Like Tracy said, your goal is to get it into the pond, and for it to dissolve however that way is. If your way is not perfect its okay, I think your wash would be a great place. Use whatever means possible.