The bridge crosses the Beaver Run which joins French Creek a little way downstream. These waterways are popular fishing spots, especially in the spring when trout season opens.
You are "fishing" for a nano. It is NOT in or near the water- no waders necessary!
I encourage you to look for at least some of the geocaches along the Horseshoe Trail, east or west. In regard to the Multi-cache described above, if you read the description and hints and logs and have good woodsman's and bushwacker's skills, you can find it without coordinates.