The rivers are filled with fish known as salmon, sturgeon,  steel head and trout. Oregon’s main rivers are Columbia, Willamette, Tualatin, Snake, Deschutes and John Day Rivers. I have been to all of these rivers, have you? Did you know that the Columbia river is the longest river in Oregon? It is 1,249 miles. It starts in Canada and ends in Astoria, Oregon where it goes into the Pacific Ocean.