re: Pics added. Looking for suggestions on a creek crossing

If you have high water flow and debris (trees) flowing during high water events, you have 2 choices.

1. Build a solid "mat" on the bottom. As someone suggested, building it out of concrete sacks will probably work. Those articulated mats used in the oilfield and in the river to reduce scour would also work, but I'm not sure you can get the equipment needed to deliver them out to the site.

2. A bridge would work, but you will need to build it high enough to stay above the high water AND minimize the piles or supports in the water. Anything in the water will cause debris to catch and eventually build up enough force from the water that the bridge will fail. Otherwise, the water backs up and flows over or around it and washes out the approaches.