According to Citrus Milo (a wonderful website if you have never checked it out) this little walk is called Menu Falls. Located near the Temple of Sinawava in Zion National Park, this beautiful little spot it perfect for pic-nicks and special moments.
To get to this little sublime spot, travel to the Temple of Sinawava or to Big Bend in Zion National Park. From either spot it is about the same distance. After exiting your vehicle you will walk down the road looking for a small trail that takes you back to this small trickle; from the temple it will be on your left, from Big Bend it will be on your right. It is probably a quarter mile in either direction to get here.
Right after you turn you will be greeted by a stair case up to a balcony that overlooks the trickling waterfall.
As mentioned this is a great spot for special moments. If you need to get engaged in Zion, I would say this is a good spot.