The Fresno River forms in the Oakhurst valley, near the western border of city limits. The primary source of the Fresno River is Lewis Fork Creek, which gathers water far northeastward into the hills adjacent to Fish Camp. Lewis Fork Creek itself has a major tributary from Nelder Creek, coming from the lower-montane Nelder Grove area and Speckerman Mountain (7,600 ft). The other major tributary is China Creek, which acts as a drainage for the ridges around the Teaford Saddle. After Oakhurst, the Fresno River runs northwest until it reaches the end of the sloped valley at the calm topography of the Fresno Flats. There the valley and hills start to meet, and the Fresno crosses Potter Ridge at around 2,000 feet.