I just built a 110ft x 10ft retaining wall using telephone poles. Buddy up with the local phone company. More than likely, the next storm that comes through your creek will take down some poles in the area as well. The line crew guys are the best people in the world (pat pat) and they will probably be glad to see you take them out of their way. It’s free and they work great. Only trouble with this is your creek. You may want to check your local codes on such things as telephone poles are pretty potent and this creek may not enjoy the preservatives!
If you would like pics of my wall, email me.