To get to Grand Falls take Interstate 40 east
out of Flagstaff and exit at Cosnino (Exit 207). Proceed
north on Cosnino Road and turn right onto Winona Road.
After about 2 miles turn north on Leupp Road. As soon as
you pass the Navajo Reservation Boundary start watching for the
dirt road that heads north (left) to Grand Falls (I think
there's a sign referring to the "Grand Falls Church"),
this is Indian Route 70. Grand Falls is about 8 miles down
this road. The road is easily traveled by car except for
maybe the last few hundred feet over a lava flow at the falls
(last time I was there, however, some people made it in a small
Toyota).
The falls seldom have much water flowing over
them except in the spring and after heavy rains upstream (It's awesome when it's
flowing heavily).
You can call the Park Rangers downstream at Wupatki National
Monument to get a report of the flow in the Little Colorado River or check the
USGS Arizona Streamflow
website.
