I have cattle but my property is in the floodplain. Can I build a fence to keep them in? The answer is yes, HOWEVER, you will need a floodplain use permit for work in the floodplain AND there are certain type of fences that are not allowed. The main idea here is to only build fences that allow stormwater runoff including any debris that might be carried along to pass freely. A no-climb fence is therefore a no-go. Rail fencing or wire strand fencing with stays are definitely possible.