Louis and clark is a dangerous ramp do to the angle of the ramp in conjuction with the lower dam,and the corp of eng. running different amounts of water there. I use the ramp at the ampitheater by the sherman miton bridge,but stay to the right if you are looking down the ramp, the left side is eroded out do to river current..On down is the 111 boat ramp its big and nice compared to the others but becarefull its out in the middle of know where and I've heard of alot of break ins....hope this helps chuck.