Great report. I've seen the road in such conditions but had my Wrangler and was able to continue on. You were wise to turn around.
As a PCT member I've been wondering what condition the spillway approach is in. The PCTA has been rerouted for a couple of years at the PCT this side of the Steel Bridge near Hook Creek. The route goes up over the top on one of the jeep roads and connects to the old HI 173 and reconnects at the parking lot where you left your car. Glad you are a survivor. This area has taken many who did not go prepared. Even those of us who have extensive experience hiking this area could be injured in a fall or bitten by a snake and have difficulty getting assistance.
Trail Coyote
Georgia Section Hiker AT 2012
PCT Section C Hiker 2010