GrantMO,
I agree with the comments on the board that you need to contact the Missouri Department of Conservation regarding your proposed plans. You will likely have to a apply for a section 404 permit, administered by the US Army Corps of Engineers to dump any fill in the creek. I have seen many instances where well-meaning individuals have placed hard-points of concrete or rubble incorrectly , and actually made the problem worse. MDC has a streams coordinator that will help you through this stuff, and there may even be some cost-share possibilities. His name is Brian Todd (812-785-2420). Tell him some guy in TX gave you his name.