: Yellowstone Rivers: Streams in the northeast portions of the Park (Lamar River drainage) are beginning shape up, dropping and clearing, that is. Some of the best fishing right now in that neck of the woods is at Trout Lake. As we advance in to summer, however, fishing slows there with weed growth and warming waters. If you are considering a visit there, do so in the next several days. Some of the largest cutthroat-rainbow trout in Park waters await you. They may even take that dry damselfly pattern if they are tired of a leech and midge pupa diet!