Trout do poorly trying to navigate pipes. The speed of water tends to wash most sediments out of pipe and water increases speed thru the tunnel. Need to either replace pipe with bridge to allow natural sediments and transition or use a 3/4 culvert with open bottom to allow the same. Most backroad crossings in this state are now done this way and results of replacing culvert is almost immediate. But wow, what a pretty place you have. Good luck.