01-Jul-2006 -- As you leave Managua to Matagalpa, there is a turn off onto a very good dirt road at 12 degrees 55.530, 86 degrees 0.301. Travel along this dirt road to about 13 degrees 0.702, 86 degrees 0.465. From there, it is about a 1400 meter walk to the confluence. Overall, the terrain is slightly uphill.
I was not able to make the walk because I was in a minivan with ten other people. The vehicle was not able to stop for me because it had already lost a trasmsission (causing us to be stranded for about two hours) and had a flat tire.
I do not know if I will ever get back, but I wanted to leave some helpful information for the next person to attempt the trip. The road we were on was not on any maps I could find. Please email me if you make it!!! I believe this is very doable.