The road to the powerhouse is usually gated. Even if it is not, don't park down there. Park at the main lot to the right of the main intersection. Carry 2/10 of a mile to the educational center then turn right down past another gate and go 4/10 of a mile to the powerhouse.
From the powerhouse parking area it is a short but steep and awkward carry down to an awkward launch point on the river. Ropes can be handy and will be necessary for rafts.