Great photos of the trail and maps from the CC Trail Coalition watch group.
Info, map, and elevation chart from Bike Washington

5 miles out: marker 6.5  (water fountain)
5.5 miles out: marker 6.0 (just past the Dalecarlia tunnel which passes under MacArthur Blvd)
6 miles out: marker 5.5
6.5 miles out: marker 5.0
7 miles out: marker 4.5  (River Road)
7.5 miles out: marker 4.0
8 miles out: mile marker 3.5.  This is at Barnes & Noble. Water fountain just beyond.
     Then go through Wisconson Ave. tunnel, then trail becomes gravel.
8.5 miles out: marker 3.0
9 miles out: marker 2.5
9.5 miles out: marker 2.0
10 miles out: marker 1.5

Water:
- 5 miles out: on Capital Crescent, MM 6.5
- 8 miles out: on Capital Crescent, just past MM 3.5