 About 40 percent of the tributaries that originally flowed over the surface of the watershed were piped or relocated during urban development, especially on the north side of the main stem.Generally, the remaining free-flowing tributaries begin south of the main stem and run north; the major exception is Crystal Springs Creek, which begins as a groundwater discharge and flows south.The other major tributaries are Hogan, Kelley, Butler, Sunshine, and Badger creeks.