check this out - good map of the water diversion tunnel and ditch system. The Hoosier Pass tunnel into Montgomery is the 3rd of 3 tunnels. Its a bit confusing as there are multiple crystal lakes in the area. But the Hoosier tunnel itself starts at the small little Crystal lake on the north side of the divide. but the system as a whole start up by Peak 10 in Crystal Creek and its associated Crystal Lakes.
http://www.schweich.com/imagehtml/coxbasinh20_17.html