Drip Feeding Outdoors

If you put a bucket in the stream in such a way that water is constantly flowing into the bucket. You could attach with a gasket and some quick thinking a small diameter hose that you could conceal and lead to your grow spot. With the water constantly flowing into the bucket, the small hole should get decent pressure pushing water out the hose to where ever you wanted it to. You could attach that to the drip rings or what ever you wanted. Attach a small valve near the plants so you can adjust the amount of water flowing out of the hose.

Just put the bucket up stream from your grow and the water pressure + gravity will help keep the water flowing. I'm pretty sure you could set up a siphon of sorts as well quite easily.