Looking for some advice.

signed up for a government reforestation program and providing I get approval soon I will be starting the land preperation latter part of this summer.
In preperation for the tree planting in the spring of "13" the forester i'm working with wants me to do a total kill on the grass and plant red clover to put nitrogen in the soil for the trees.
The property is 36 acres with 10 of it in pond. I plan on leaving a 20' or so buffer of high grass at the pond edge and maybe another on up the hill a little further.
My concern is the chemical I will be killing the grass with. Is there a better or worse chemical to use that wont effect the pond in a bad way. And any suggestions or other concerns would be greatly apprieciated. Thanks

"If you aim at nothing you'll hit it every time"

Zig Ziglar