Drew, I am still learning about all of this stuff but I would think that it would be OK to put in the swales. The swales are made to capture/slow down any
water that comes down the slope. Allowing it to soak into the ground. So if you want to keep the water up slope for a little while longer before it gets to the pond I would think a swale would be great for that. Might also stop any errosion if you have that. The water would soak into the ground and still move down hill towards the pond, only
underground rather than along the surface. Do you get a lot of rain in your area.
Some folks also build ponds up higher on the slope and let the swales collect water to fill the new ponds.