Jon, The old areas below the Mohave dam, including the Spillway area are now closed. You could park at the west end of the Mohave Dam. The road there is not HWY 173. HWY 173 is just south of there at a T in the road. At the T, 173 continues on east up into the hills and eventually to the north side of Arrowhead lake. One suggestion, if you take 173 east from the T it quickly turns to dirt. Once on the dirt road go 4.8 miles and you will be at a small white bridge which crosses Kinely creek. You can park at a pull out spot there. Cross the road to the north side of the bridge and a trail starts just past an old pipe gate just off the road. This trail is called the Bradford ridge trail and will take you to the PCT and if you turn right when you hit the PCT you will shortly be at DCHS. Going this way is two and a half miles and the parking area is not prone to vandalism like the areas around the Mohave Dam.