It's about 15-20 min from Riverside to the Avi. They usually start letting the river drop after 0pm. But for 4th of july they usually let it stay up at night since so many boaters will be on the water.

About +/- 14 miles
try this:

258.0 Fort Mojave Indian Reserva tion boundary (the Avi is about 260 +/-)
261.3 Fort Mojave Indian Reserva tion boundary
261.4 Natural gas pipeline (under river)
265.4 Private marina (L), RIVIERA, Arizona (L)
265.9 Stream gage, USBR, Colorado River at Big Bend
266.0 Overhead natural gas pipeline
270.2 Private marina (L)
271.0 Silver Creek Wash (L)
271.6 Secret Pass Canyon (L)
272.4 Pumping Plant for Mohave Generating Station(R)
273.0 Coal slurry pipeline (under river)
273.0 BULLHEAD CITY, Arizona (L)
274.0 LAUGHLIN, Nevada (R)

from:
http://www.usbr.gov/lc/region/pao/rvrmiles.pdf

thats all I got
Daniel
Mash on it

its about 10-12 miles on the water   

Hey Danny

NO, unfortunatley, not alot of gas docks like in the good ol days
the only gas 'on the River' that I know of is at the AVI, Needles Marina, Park Moabi & The London Bridge in Havasu
 

Well then I guess it would be floatin' one way or Dana will have to share the back seat with a
fuel jug instead of a river hottie ! Ha !  He ain't gonna like that. 

Danny